ARTIFICIAL ENVIRONMENT FOR EFFICIENT UPTATE OF FERTILIZERS AND OTHER AGROCHEMICALS IN SOIL

Abstract

A unit for delivery of agrochemicals to the roots of a plant comprising one or more root development zones, and one or more agrochemical zones containing at least one agrochemical, wherein the agrochemical zones are formulated to release the at least one agrochemical into the root development zones in a controlled release manner when the root development zones are hydrated, and wherein the weight ratio of the root development zones to the agrochemical zones in a dry unit is 0.05:1 to 0.32:1.

Description

This application claims priority of U.S. Provisional Application No. 61/793,697, filed Mar. 15, 2013, the content of which is hereby incorporated by reference in its entirety.

Throughout this application, various publications are referenced, including referenced in parenthesis. Full citations for publications referenced in parenthesis may be found listed at the end of the specification immediately preceding the claims. The disclosures of all referenced publications in their entireties are hereby incorporated by reference into this application in order to more fully describe the state of the art to which this invention pertains.

BACKGROUND OF INVENTION

Current practices and technologies yield poor agrochemical use efficiency by plants due to over application (up to 50%) (Shaviv and Mikkelsen 1993). Excessive application of agrochemicals has adverse effects on the environment and is costly for farmers (Shaviv and Mikkelsen 1993). Additionally, many soils and climates are not suitable for growing crops (Habarurema and Steiner, 1997; Nicholson and Farrar, 1994).

New practices and technologies are needed for efficient application of fertilizers and other agrochemicals for improving plant growth.

SUMMARY OF THE INVENTION

The invention provides a unit for delivery of agrochemicals to the roots of a plant comprising:

• • i) one or more root development zones, and
  • ii) one or more agrochemical zones containing at least one agrochemical,
  • wherein the agrochemical zones are formulated to release the at least one agrochemical into the root development zones in a controlled release manner when the root development zones are swelled, and
  • wherein the weight ratio of the root development zones to the agrochemical zones in a dry unit is 0.05:1 to 0.32:1.

The invention provides a unit for delivery of agrochemicals to the roots of a plant comprising:

• • i) one or more root development zones, and
  • ii) one or more agrochemical zones containing at least one agrochemical,
  • wherein the agrochemical zones are formulated to release the at least one agrochemical into the root development zones in a controlled release manner when the root development zones are swelled, and
  • wherein the total volume of the root development zones in the unit is at least 0.2 mL when the unit is fully swelled.

The invention provides a method of growing a plant, comprising adding at least one unit of the invention to the medium in which the plant is grown.

The invention provides a method of reducing environmental damage caused by an agrochemical, comprising delivering the agrochemical to the root of a plant by adding at least one unit of the invention to the medium of the plant.

The present invention provides a method of minimizing exposure to an agrochemical, comprising delivering the agrochemical to the root of a plant by adding at least one unit of the invention to the medium of the plant.

The present invention provides a method of generating an artificial zone with predetermined chemical properties within the root zone of a plant, comprising:

• • i) adding one or more units of the invention to the root zone of the plant; or
  • ii) adding at one or more units of the invention to the anticipated root zone of the medium in which the plant is anticipated to grow.

The present invention provides a method of increasing the growth rate of a plant, comprising (i) adding one or more units of the invention to a medium where the plant is growing or is to be grown, and (ii) growing the plant, wherein the plant grows faster in the medium containing the units than in the medium not containing the units.

The present invention provides a method of increasing the size of a plant, comprising (i) adding one or more units of the invention to a medium where the plant is growing or is to be grown, and (ii) growing the plant, wherein the plant grows larger in the medium containing the units than in the medium not containing the units.

The present invention provides a method of increasing N, P, K, and/or micronutrient (e.g. Zn, Fe, Cu) uptake by a plant, comprising (i) adding one or more units of the invention to a medium where the plant is growing or is to be grown, and (ii) growing the plant, wherein the N, P, and/or K uptake of the plant is greater in the medium containing the units than in the medium not containing the units.

The present invention provides a method of protecting a plant from low ambient temperatures, comprising (i) adding one or more units of the invention to a medium where the plant is growing or is to be grown, and (ii) growing the plant, wherein plants grown in the medium containing the units have greater survival rates under low ambient temperatures than plants grown in the medium not containing the units.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1. Swelling behavior of semi-synthetic hydrated SAPs following hydration and rehydration cycles in water.

FIG. 2. Swelling behavior of hydrated SAPs following hydration and rehydration cycles in sandy soil.

FIG. 3. Swelling behavior of hydrated SAPs following hydration and rehydration cycles in sandy soil loose soil.

FIG. 4. Dissolved oxygen level in the water reservoir opposite the oxygen saturated water.

FIG. 5. Silica coating process on poly sugar beads.

FIG. 6. Beehive like structure made by the Bentonite filler.

FIG. 7. Schematic illustration of the hybrid encapsulation method.

FIG. 8. Release of nitrate from internal zone without (left bars) and with (right bars) Silica coating.

FIG. 9. Release of PO₄ from internal zone incorporated with Bentonite filler over time.

FIG. 10A-G. (A) Pea roots growth in CMC—Lab. (B) Corn roots growth in Alginate—Lab. (C) Pea root growth in k-Carrageenan—Lab. (D) Pea root growth on CMC—Lab. (E) Corn root grown in Fully synthetic—Lab. (F) Corn root grown in Fully synthetic—Lab. (G) Corn roots growth in Alginate—Lab.

FIG. 11. Phase 1: Banding and incorporating dry “beads”, made from an external zone (hydrogel) and internal zone (coated minerals) into the upper soil profile. Phase 2: Following watering, the beads swell (up to, e.g., 5 cm in diameter) and agrochemicals diffuse to the external zone & soil. Phase 3: Roots grow and are sustained in/near the external zone, and uptake lasts a few weeks (6-8).

FIG. 12. Non-limiting examples of bead content and dimensions.

FIG. 13. Dissolved Oxygen System.

FIG. 14. The field plot experimental setup of Example 3.

FIG. 15. Soil temperatures at the experimental site of Example 3. Top line shows maximum soil temperatures and bottom line shows minimum soil temperatures.

FIG. 16. Relative weight of the hydrogels and water application over time in Example 3.

FIG. 17. Final surface areas of the hydrogel units of Example 3.

FIG. 18. Surface areas of the hydrogel units of Example 3 over time.

FIG. 19. Final surface area to volume ratio of the hydrogel units of Example 3.

FIG. 20. Final minimal distance values of the hydrogel units of Example 3.

FIG. 21. Minimal distance of the hydrogel units of Example 3 versus time.

FIG. 22. Final stiffness values of the hydrogel units of Example 3.

FIG. 23. Stiffness of the hydrogel units of Example 3 versus time.

FIG. 24A-I. Photos of the hydrogels of Example 3 from plots A-C at the end of the experiment. FIG. 24A: fully synthetic; FIG. 24B: Semisynthetic CMC 6% AAm; FIG. 24C: Semisynthetic CMC 6% AA; FIG. 24D: Semisynthetic CMC 25% AA; FIG. 24E: Semisynthetic CMC 50% AA; FIG. 24F: Polysugars Alginate; FIG. 24G: Semisynthetic CMC 6% AAm-Large; FIG. 24H: Semisynthetic CMC 50% AA-large; FIG. 24I: Semisynthetic CMC 6% AAm-Small.

FIG. 25A-I. Photos of the hydrogels of Example 3 from plot D at the end of the experiment. Left panels of FIGS. 25A-G show hydrogels in situ. Right panels of FIGS. 25A-G show samples where roots penetrated through the hydrogel. FIG. 25A: fully synthetic; FIG. 25B: Semisynthetic CMC 6% AAm; FIG. 25C: Semisynthetic CMC 6% AA; FIG. 25D: Semisynthetic CMC 25% AA; FIG. 25E: Semisynthetic CMC 50% AA; FIG. 25F: Semisynthetic CMC 6% AAm-Large; FIG. 25G: Semisynthetic CMC 50% AAm-Large; FIG. 25H: Semisynthetic CMC 25% AA; FIG. 25I: Semisynthetic CMC 6% AAm-Large.

FIG. 26. Twenty three rotated weighing lysimeters used in Example 4.

FIG. 27A-B. Dehydrated cylindrical shape fertilizer units of Example 4 prior to application (FIG. 27A) and partly hydrated fertilizer units at application (FIG. 27B).

FIG. 28. Application dose of N, P, and K per plant for each treatment of Example 4, stage 1. Slow release: left bars; fertilizer units (Full): middle bars; fertilizer units (Half): right bars.

FIG. 29A-C. Plant height (FIG. 29A), number of leaves (FIG. 29B), and SPAD values (FIG. 29C) of the plants of Example 4, stage 1.

FIG. 30A-C. Plant dry matter (FIG. 30A), absolute NPK uptake amount (FIG. 30B), and NPK uptake efficiency (FIG. 30C) of the plants of Example 4, stage 1. Fertilizer units (Full): left bars; Fertilizer units (Half): middle bars; Slow release: right bars.

FIG. 31. Relative residuals of N, P, and K in the fertilizer units following harvest of the plants of Example 4, stage 1. Fertilizer units (Full): left bars; Fertilizer units (Half): right bars.

FIG. 32A-D. Plant height (FIG. 32A), number of leaves (FIG. 32B), SPAD values (FIG. 32C), and wet biomass (FIG. 32D) for plants of stage 2 of Example 4 grown in sandy soil. FIG. 32D: left bars show data for empty units plus fertigation (Full) and right bars show data for fertilizer units (Full).

FIG. 33A-D. Plant height (FIG. 33A), number of leaves (FIG. 33B), SPAD values (FIG. 33C), and wet biomass (FIG. 33D) for plants of stage 3 of Example 4 grown in Growing Media. FIG. 33D: left bars show data for SR, middle bars show data for fertilizer units, and right bars show data for fertigation.

FIG. 34A-D. Plant height (FIG. 34A), number of leaves (FIG. 34B), SPAD values (FIG. 34C), and wet biomass (FIG. 34D) for plants of stage 3 of Example 4 grown in clayey Media. FIG. 34D: left bars show data for fertilizer units and right bars show data for SR.

FIG. 35A-Q. Photos of fertilizer units and plants at the end of Example 4. FIG. 35A: hydrated fertilizer unit; FIG. 35B: root penetration inside hydrated fertilizer unit; FIG. 35C: root distribution within hydrated fertilizer unit; FIG. 35D: root distribution within hydrated fertilizer unit; FIG. 35E: stage 1 fertilizer unit (full); FIG. 35F: stage 1 fertilizer unit (half); FIG. 35G: stage 1 SR (full); FIG. 35H: fertilizer unit full (right), fertilizer unit half (left) and SR (middle); FIG. 35I: stage 2 fertilizer unit (full); FIG. 35J: stage 2 fertilizer unit (full); FIG. 35K: stage 2 empty unit plus fert.; FIG. 35L: stage 2 empty unit plus fert.; FIG. 35M: stage 3 growing media and fertilizer unit; FIG. 35N: stage 3 growing media and SR; FIG. 35O: stage 3 growing media and fert.; FIG. 35P: stage 3 clay and fertilizer unit; FIG. 35Q: stage 3 clay and SR.

FIG. 36. Plot design of Example 5.

FIG. 37A-E. Measured parameters throughout the growing season for plants of Example 5. FIG. 37A: sunflower height; FIG. 37B: sunflower number of leaves; FIG. 37C: sunflower chlorophyll content optical sensor-SPAD values; FIG. 37D: cabbage leaves diameter; FIG. 37E: cabbage number of leaves.

FIG. 38A-B. Macro-nutrient (N, P, and K) content in sunflower and cabbage leaves of Example 5. Left bars show data for fertilizer units, middle bars show data for SR, and right bars show data for fertigation.

FIG. 39A-B. FIG. 39A: ratio between cabbage head diameter and weight in cabbage plants of Example 5; FIG. 39B: calculated cabbage head weight over the growing season of Example 5.

FIG. 40. Cabbage dry matter and N-uptake in the cabbage plants of Example 5. FIG. 40A: final cabbage dry matter per plant in three subplots; FIG. 40B: cabbage nitrogen uptake per plant in three subplots. Left bars show data for fertilizer units, middle bars show data for SR, and right bars show data for Fertigation.

FIG. 41. Sunflower grain yield and nitrogen uptake per meter in the 3 subplots of Example 5. Left bars show data for fertilizer units, middle bars show data for SR, and right bars show data for fertigation.

FIG. 42. NPK residuals in fertilizer units for each plot and crop of Example 5; FIG. 42A: cabbage; FIG. 42B: sunflower. Left bars show data for plot 1, middle bars show data for plot 2, and right bars show data for plot 3.

FIG. 43. Final N soil content in the root zone (>30 cm) for each crop of Example 5. Left bars show data for sunflower and right bars show data for cabbage.

FIG. 44A-H. Calculated N mass balance in the root zone of cabbage and sunflower plots of Example 5. FIG. 44A: fertilizer unit, SR, and Fert initial N mass balance for cabbage plots; FIG. 44B: fertilizer unit final N balance for cabbage plots; FIG. 44C: SR final N balance for cabbage plots; FIG. 44D: Fert final N balance for cabbage plots; FIG. 44E: fertilizer unit, SR, and Fert initial N mass balance for sunflower plots; FIG. 44F: fertilizer unit final N balance for sunflower plots; FIG. 44G: SR final N balance for sunflower plots; FIG. 44H: Fert final N balance for sunflower plots.

FIG. 45A-C. Photographs showing the hydrated fertilizer units of Example 5. FIG. 45A: hydrated fertilizer unit; FIG. 45B: root distribution around hydrated fertilizer units; FIG. 45C: Root penetration inside hydrated fertilizer unit.

FIG. 46. Fertilizer units made according to the process of Example 6.

FIG. 47. A fully swelled fertilizer unit made according to the process of Example 6 compared to a dried fertilizer unit made according to the process of Example 6.

FIG. 48. Combined marketable yield of lettuce and celery from the crops of Example 8 fertilized with fertilizer units or solid fertilizer.

DETAILED DESCRIPTION OF THE INVENTION

The invention provides a unit for delivery of agrochemicals to the roots of a plant comprising:

• • i) one or more root development zones, and
  • ii) one or more agrochemical zones containing at least one agrochemical,
  • wherein the agrochemical zones are formulated to release the at least one agrochemical into the root development zones in a controlled release manner when the root development zones are swelled, and
  • wherein the weight ratio of the root development zones to the agrochemical zones in a dry unit is 0.05:1 to 0.32:1.

In some embodiments, the total volume of the root development zones in the unit is at least 0.2 mL when the unit is fully swelled.

The invention provides a unit for delivery of agrochemicals to the roots of a plant comprising:

• • i) one or more root development zones, and
  • ii) one or more agrochemical zones containing at least one agrochemical,
  • wherein the agrochemical zones are formulated to release the at least one agrochemical into the root development zones in a controlled release manner when the root development zones are swelled, and
  • wherein the total volume of the root development zones in the unit is at least 0.2 mL when the unit is fully swelled.

In some embodiments, the weight ratio of the root development zones to the agrochemical zones in a dry unit is 0.05:1 to 0.32:1.

In some embodiments, the weight ratio of the root development zones to the agrochemical zones in a dry unit is 0.05:1, 0.1:1, 0.15:1, 0.2:1, 0.25:1, or 0.3:1.

In some embodiments, the weight ratio of the root development zones to the agrochemical zones in a dry unit is 0.01:1 to 0.5:1, 0.01:1 to 0.02:1, 0.01:1 to 0.03:1, 0.01:1 to 0.04:1, 0.01:1 to 0.05:1, 0.3:1 to 0.4:1, 0.3:1 to 0.4:1, 0.3:1 to 0.5:1.

In some embodiments, the total volume of the root development zones in the unit is at least 0.2 mL, 0.5 mL, at least 1 mL, at least 2 mL, at least 5 mL, at least 10 mL, at least 20 mL, at least 30 mL, at least 40 mL, at least 50 mL, at least 60 mL, at least 70 mL, at least 80 mL, at least 90 mL, at least 100 mL, at least 150 mL, at least 200 mL, at least 250 mL, at least 300 mL, at least 350 mL, at least 400 mL, at least 450 mL, at least 500 mL, at least 550 mL, at least 600 mL or larger than 600 mL when the unit is 1%, 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 1-50%, or 5-50% swelled.

In some embodiments, the total volume of the root development zones in the unit is at least 2 mL when the unit is 1%, 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 1-50%, or 5-50% swelled.

In some embodiments, the total volume of the root development zones in the unit is greater than 2 mL, 2-3 mL, 3-4 mL, 4-5 mL, 2-5 mL, 2-10 mL, 5-10 mL, 5-20 mL, 10-15 mL, 10-20 mL, 15-20 mL, 10-40 mL, 20-40 mL, 20-80 mL, 40-80 mL, 50-100 mL, 75-150 mL, 100-150 mL, 150-300 mL, 200-400 mL, 300-600 mL, or 600-1000 mL when the unit is 1%, 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 1-50%, or 5-50% swelled.

In some embodiments, the total volume of the root development zones in the unit is at least 0.2 mL, at least 0.5 mL, at least 1 mL, at least 2 mL, at least 5 mL, at least 10 mL, at least 20 mL, at least 30 mL, at least 40 mL, at least 50 mL, at least 60 mL, at least 70 mL, at least 80 mL, at least 90 mL, at least 100 mL, at least 150 mL, at least 200 mL, at least 250 mL, at least 300 mL, at least 350 mL, at least 400 mL, at least 450 mL, at least 500 mL, at least 550 mL, at least 600 mL or larger than 600 mL when the unit is fully swelled.

In some embodiments, the total volume of the root development zones in the unit is at least 2 mL when the unit is fully swelled.

In some embodiments, the total volume of the root development zones in the unit is greater than 2 mL, 2-3 mL, 3-4 mL, 4-5 mL, 2-5 mL, 2-10 mL, 5-10 mL, 5-20 mL, 10-15 mL, 10-20 mL, 15-20 mL, 10-40 mL, 20-40 mL, 20-80 mL, 40-80 mL, 50-100 mL, 75-150 mL, 100-150 mL, 150-300 mL, 200-400 mL, 300-600 mL, or 600-1000 mL when the unit is fully swelled.

In some embodiments, the total volume of the root development zones when the unit is 1%-100% swelled is large enough to contain at least 10 mm of a root having a diameter of 0.5 mm.

In some embodiments, the total volume of the root development zones when the unit is 1-100% swelled is large enough to contain 10-50 mm of a root having a diameter of 0.5-5 mm.

In some embodiments, the total volume of the root development zones when the unit is 1%, 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 1-50%, or 5-50% swelled is large enough to contain at least 10 mm of a root having a diameter of 0.5 mm.

In some embodiments, the total volume of the root development zones when the unit is 1%, 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 1-50% or 5-50% swelled is large enough to contain 10-50 mm of a root having a diameter of 0.5-5 mm.

In some embodiments, the unit has a dry weight of 0.1 g to 20 g.

In some embodiments weight of the dry unit is 1-10 g. In some embodiments, the weight of the dry unit is 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 g.

In some embodiments, the total weight of the agrochemical zones of the unit is 0.05 to 5 grams.

In some embodiments, the unit is in the shape of a cylinder.

In some embodiments, the unit is in the shape of a polyhedron.

In some embodiments, the unit is in the shape of a cube.

In some embodiments, the unit is in the shape of a disc.

In some embodiments, the unit is in the shape of a sphere.

In some embodiments, the agrochemical zones and the root development zones are adjoined.

In some embodiments, the unit consists of one root development zone which is next to one agrochemical zone.

In some embodiments, the agrochemical zones are partially contained within the root development zones such that the surface of the unit is formed by both the root development zones and the agrochemical zones.

In some embodiments, the root development zones are partially contained within the agrochemical zones such that the surface of the unit is formed by both the root development zones and the agrochemical zones.

In some embodiments, an agrochemical zone is sandwiched between two root development zones.

In some embodiments, the agrochemical zone is surrounded by a root development zone which forms a perimeter around the agrochemical zone but which covers less than all of the surface of the agrochemical zone, or vice versa. In some embodiments, the perimeter is ring shaped.

In some embodiments, the unit is a bead comprising an external zone surrounding an internal zone, wherein the root development zones form the external zone and the agrochemical zones form the internal zone.

In some embodiments, the unit comprises one root development zone and one agrochemical zone.

In some embodiments, the root development zones comprise a super absorbent polymer (SAP).

In some embodiments, the root development zones are capable of absorbing at least about 10, 15, 20, 25, 30, 35, 40, 45, 50, 75, 80, 85, 90, 95, 100, 200, 300, 400, 500, or 1000 times their weight in water.

In some embodiments, the root development zones are capable of absorbing at least about 20-30 times their weight in water.

In some embodiments, the root development zones are permeable to oxygen.

In some embodiments, the root development zones are permeable to oxygen such that at least about 6 mg/L of dissolved oxygen is maintained in the root development zones when the root development zones are swelled.

In some embodiments, the root development zones when fully swelled are at least about 70, 75, 80, 85, 90, 95, or 100% as permeable to oxygen as swelled alginate or swelled semi-synthetic CMC.

In some embodiments, the root development zones comprise an aerogel, a hydrogel or an organogel.

In some embodiments, the root development zones comprise a hydrogel.

In some embodiments, the root development zones comprise an aerogel.

In some embodiments, the root development zones comprise a geotextile.

In some embodiments, the root development zones comprise a sponge.

In some embodiments, the wherein the root development zones further comprise a polymer, a porous inorganic material, a porous organic material, or any combination thereof.

In some embodiments, the agrochemical zones further comprise an aerogel, a hydrogel, an organogel, a polymer, a porous inorganic material, a porous organic material, or any combination thereof.

In some embodiments, roots of a plant are capable of penetrating the root development zones when the root development zones are about 1%, 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 1-50% or 5-50% swelled.

In some embodiments, roots of a plant are capable of growing within the root development zones when the root development zones are swelled.

In some embodiments, roots of a plant are capable of growing within the root development zones when the root development zones are about 1%, 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 1-50% or 5-50% swelled.

In some embodiments, microbes are capable of penetrating and growing within the root development zones when the root development zones are swelled.

In some embodiments, the plant is a crop plant.

In some embodiments, the crop plant is a wheat plant, a maize plant, a soybean plant, a rice plant, a barley plant, a cotton plant, a pea plant, a potato plant, a tree crop plant, or a vegetable plant.

In some embodiments, the root development zones are capable of repeated swelling cycles that each comprises hydration followed by dehydration.

In some embodiments, the root development zones are capable of repeated swelling cycles in soil that each comprise hydration followed by dehydration while in the soil.

In some embodiments, the unit is in the shape of a sphere or an equivalent polyhedron.

In some embodiments, the unit is in the shape of a sphere or an equivalent polyhedron after repeated swelling cycles.

In some embodiments, the root development zones, when swelled, maintain at least about 75%, 80%, 85%, 90%, or 95% of their water content over a period of at least about 25, 50, 100, or 150 hours in soil.

In some embodiments, the root development zones, when swelled, maintain at least about 75%, 80%, 85%, 90%, or 95% of their water content over a period of at least about 25, 50, 100, or 150 hours in sandy soil.

In some embodiments, the root development zones, when swelled, maintain at least about 75%, 80%, 85%, 90%, or 95% of their volume over a period of at least about 25, 50, 100, or 150 hours in soil.

In some embodiments, the root development zones, when swelled, maintain at least about 75%, 80%, 85%, 90%, or 95% of their volume over a period of at least about 25, 50, 100, or 150 hours in sandy soil.

In some embodiments, the root development zones, when swelled, maintain their shape over a period of at least about 25, 50, 100, or 150 hours in soil.

In some embodiments, the root development zones, when swelled, maintain their shape over a period of at least about 25, 50, 100, or 150 hours in sandy soil.

In some embodiments, the root development zones, when swelled, maintain their shape after repeated swelling cycles that each comprises hydration followed by dehydration.

In some embodiments, the root development zones, when swelled maintain their shape after at least 3 swelling cycles that each comprises hydration followed by dehydration.

In some embodiments, the root development zones are biodegradable.

In some embodiments, the root development zones, when swelled in soil, have a pH or osmotic pressure that differs from the pH or osmotic pressure of the surrounding soil by at least about 10%.

In some embodiments, the root development zones do not contain the at least one agrochemical before the unit is swelled for the first time.

In some embodiments, the root development zones further comprise the at least one agrochemical before the unit is swelled for the first time.

In some embodiments, the amount of the at least one agrochemical in the root development zones is about 5%, 10%, 15% or 20% (w/w) of the amount of the at least one agrochemical that is in the agrochemical zones.

In some embodiments, the widest part of the unit is about 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 cm, or more than 10 cm when the root development zones are about 1%, 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 1-50% or 5-50% swelled.

In some embodiments, when the root development zones are about 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, or 5-50% swelled, the total weight of the root development zones is at least about 2, 3, 4, 5, 6, 7, 8, 9, 10, 20, 30, 40, 50, 60, 70, 80, 90, 100 or more than 100 times greater than the total weight of the agrochemical zones.

In some embodiments, the root development zones comprise a synthetic hydrogel, a natural carbohydrate hydrogel, or a pectin or protein hydrogel, or any combination thereof.

In some embodiments, the synthetic hydrogel comprises acrylamide, an acrylic derivative, or any combination thereof.

In some embodiments, the natural carbohydrate hydrogel comprises agar, cellulose, chitosan, starch, hyaluronic acid, a dextrine, a natural gum, a sulfated polysaccharide, or any combination thereof.

In some embodiments, the pectin or protein hydrogel comprises gelatin, a gelatin derivative, collagen, a collagen derivative, or any combination thereof.

In some embodiments, the root development zones comprise a natural super absorbent polymer (SAP), a poly-sugar SAP, a semi-synthetic SAP, a fully-synthetic SAP, or any combination thereof.

In some embodiments, the root development zones comprise a combination of at least one natural SAP and at least one semi-synthetic or synthetic SAP.

In some embodiments, the root development zones comprise a poly-sugar SAP.

In some embodiments, the poly-sugar SAP is alginate.

In some embodiments, the alginate is at least about 0.2% alginate.

In some embodiments, the root development zones comprise a semi-synthetic SAP.

In some embodiments, the semi-synthetic SAP is a CMC-g-polyacrylic acid SAP.

In some embodiments, the Caboxymethyl cellulose (CMC) grafted polyacrylic acid SAP comprises 6% CMC relative to the acrylic monomers (Acrylamide-acrylic), 6% CMC relative to acrylic acid, 25% CMC relative to acrylic acid, or CMC 50% AA.

In some embodiments, the CMC grafted SAP comprises 5-50% CMC relative the acrylic monomers.

In some embodiments, the CMC grafted SAP comprises 6-12% CMC relative the acrylic monomers.

In some embodiments, the semi-synthetic SAP is k-carrageenan cross-linked-polyacrylic acid SAP.

In some embodiments, the SAP is other than alginate or a k-carrageenan cross-linked-polyacrylic acid SAP.

In some embodiments, the root development zones comprise a fully synthetic SAP.

In some embodiments, the fully synthetic SAP is acrylic acid or acrylic amide or any of the combinations thereof.

In some embodiments, the amount of cross-linker in the root development zones is below 5% relative to the total monomer content by weight. In some embodiments, the amount of cross-linker in the root development zones is below 2% relative to the total monomer content by weight. In some embodiments, the amount of cross-linker in the root development zones is below 1% relative to the total monomer content by weight.

In some embodiments, the polymer content of a swelled unit is below 5% by weight. In some embodiments, the polymer content of a swelled unit is below 4%, below 3%, below 2%, or below 1% by weight.

In some embodiments, the root development zones further comprise at least one oxygen carrier that increases the amount of oxygen in the root development zones compared to corresponding root development zones not comprising the oxygen carrier.

In some embodiments, the at least one oxygen carrier is a perfluorocarbon.

In some embodiments, the agrochemical zones comprise an organic polymer, a natural polymer, or an inorganic polymer, or any combination thereof.

In some embodiments, the agrochemical zones are partially or fully coated with a coating system.

In some embodiments, the coating system dissolves into the root development zones when the root development zones are swelled.

In some embodiments, the coating system slows the rate at which the at least one agrochemical dissolves into the root development zones when the root development zones are swelled.

In some embodiments, the units comprise a coating system which covers all surfaces of the agrochemical zones which would otherwise be on the surface of the unit and which is impermeable to the at least one agrochemical.

In some embodiments, the coating system is silicate or silicon dioxide.

In some embodiments, the coating system is a polymer.

In some embodiments, the coating system is an agrochemical.

In some embodiments, the agrochemical zones comprise a polymer.

In some embodiments, the polymer is a highly cross-linked polymer.

In some embodiments, the highly cross-linked polymer is a poly-sugar or a poly-acrylic polymer.

In some embodiments, the agrochemical zones comprises a filler.

In some embodiments, the filler comprises a cellulosic material, a cellite, a polymeric material, a silicon dioxide, a phyllosilicate, a clay mineral, metal oxide particles, porous particles, or any combination thereof.

In some embodiments, the filler comprises a phyllosilicate of the serpentine group.

In some embodiments, the a phyllosilicate of the serpentine group is antigorite (Mg₃Si₂O₅(OH)₄), chrysotile (Mg₃Si₂O₅(OH)₄), or lizardite (Mg₃Si₂O₅(OH)₄).

In some embodiments, the filler comprises a clay mineral, which is halloysite (Al₂Si₂O₅(OH)₄), kaolinite (Al₂Si₂O₅(OH)₄), illite ((K,H₃O)(Al,Mg,Fe)₂(Si,Al)₄O₁₀[(OH)₂,(H₂O)]), montmorillonite ((Na,Ca)_0.33(Al,Mg)₂Si₄O₁₀(OH)₂.nH₂O), vermiculite ((MgFe,Al)₃(Al,Si)₄O₁₀(OH)₂.4H₂O), talc (Mg₃Si₄O₁₀(OH)₂), palygorskite ((Mg,Al)₂Si₄O₁₀(OH).4(H₂O), or pyrophyllite (Al₂Si₄O₁₀(OH)₂).

In some embodiments, the filler comprises a phyllosilicate of the mica group.

In some embodiments, the phyllosilicate of the mica group is biotite (K(Mg,Fe)₃(AlSi₃)O₁₀(OH)₂), muscovite (KAl₂(AlSi₃)O₁₀(OH)₂), phlogopite (KMg₃(AlSi₃)O₁₀(OH)₂), lepidolite (K(Li,Al)_2-3(AlSi₃)O₁₀(OH)₂), margarite (CaAl₂(Al₂Si₂)O₁₀(OH)₂), glauconite ((K,Na)(Al,Mg,Fe)₂(Si,Al)₄O₁₀(OH)₂), or any combination thereof.

In some embodiments, the filler comprises a phyllosilicate of the chlorite group.

In some embodiments, the a phyllosilicate of the chlorite group is chlorite ((Mg,Fe)₃(Si,Al)₄O₁₀(OH)₂.(Mg,Fe)₃(OH)₆).

In some embodiments, the filler forms a beehive-like structure.

In some embodiments, the beehive-like structure is microscopic.

In some embodiments, the filler comprises clay.

In some embodiments, the filler comprises zeolite.

In some embodiments, the agrochemical zones comprise at least about 0.05, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, or 1 grams of the at least one agrochemical.

In some embodiments, the agrochemical zones comprise 1-10 grams of the at least one agrochemical.

In some embodiments, the agrochemical zones are about 30%, 35%, 40%, 45%, 50%, 55%, or 60% of the at least one agrochemical by weight.

In some embodiments, the agrochemical zones are biodegradable.

In some embodiments, the unit comprises one agrochemical zone.

In some embodiments, the unit comprises 2, 3, 4, 5, 6, 7, 8, 9, 10 or more than 10 agrochemical zones.

In some embodiments, the unit comprises 2, 3, 4, 5, 6, 7, 8, 9, 10 or more than 10 root development zones.

In some embodiments, the at least one agrochemical is:

• • i) at least one fertilizer compound;
  • ii) at least one pesticide compound,
  • iii) at least one hormone compound;
  • iv) at least one drug compound;
  • v) at least one chemical growth agents;
  • vi) at least one enzyme;
  • vii) at least one growth promoter; and/or
  • viii) at least one microelement.

In some embodiments, the at least one fertilizer compound is a natural fertilizer.

In some embodiments, the at least one fertilizer compound is a synthetic fertilizer.

In some embodiments, the at least one pesticide compound is:

• • i) at least one insecticide compound;
  • ii) at least one nematicide compound;
  • iii) at least one herbicide compound; and/or

iv) at least one fungicide compound.

In some embodiments, the at least one insecticide compound is imidacloprid.

In some embodiments, the at least one herbicide compound is pendimethalin.

In some embodiments, the at least one fungicide compound is azoxystrobin.

In some embodiments, the at least one nematicide compound is fluensulfone.

In some embodiments, the at least one fertilizer compound is PO₄, NO₃, (NH₄)₂SO₂, NH₄H₂PO₄, and/or KCl.

In some embodiments, the at least one fertilizer compound comprises multiple fertilizer compounds which include PO₄, NO₃, (NH₄)₂SO₂, NH₄H₂PO₄, and/or KCl.

In some embodiments, the at least one agrochemical is at least one fertilizer compound and at least one pesticide compound.

In some embodiments, the at least one agrochemical is at least one pesticide compound.

In some embodiments, the at least one agrochemical is at least one fertilizer compound.

In some embodiments, the at least one pesticide compound is at least one pesticide compound that is not suitable for application to an agricultural field.

In some embodiments, the at least one pesticide compound that is not suitable for application to an agricultural field is too toxic to be applied to an agricultural field.

In some embodiments, the at least one pesticide compound is toxic to animals other than arthropods or mollusks when applied to an agricultural field in an amount that is sufficient to kill an arthropod or a mollusk.

In some embodiments, the at least one agrochemical is released from the agrochemical zones over a period of at least about one week when the root development zones are swelled.

In some embodiments, the at least one agrochemical is released from the agrochemical zones into the root development zones over a period of at least about 2, 3, 4, 5, 6, 7, 8, 9, 10, or 20 weeks when the root development zones are swelled.

In some embodiments, the at least one agrochemical is released from the agrochemical zones into the root development zones over a period of at least about 2, 3, 4, 5, 6, 7, 8, 9, 10, or 20 weeks when the root development zones are about 1%, 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 1-50% or 5-50% swelled.

In some embodiments, when the root development zones are swelled and the unit is in soil, the at least one agrochemical diffuses from the surface of the unit into the surrounding soil at a linear rate beginning about 25 days after hydration.

In some embodiments, when the root development zones of the unit are swelled and the unit is in soil, the at least one agrochemical diffuses from the surface of the unit into the surrounding soil for at least about 50 or 75 days after hydration.

In some embodiments, the unit is not swelled.

In some embodiments, the unit contains less than about 35%, 30%, 25%, 20%, 15%, or 10% water by weight.

In some embodiments, the unit comprises one or more interface zone between the agrochemical zones and the root development zones, which interface zone is formed by at least one insoluble salt or solid, at least one cross-linking agent, or at least one inorganic compound.

In some embodiments, diffusion between the root development zones and the agrochemical zones is limited by altering the pH or the cation concentration in the agrochemical zones, the root development zones, or the interface zone.

In some embodiments, diffusion between the root development zones and the agrochemical zones is limited by altering the pH and/or cation concentration in the agrochemical zone or the root development zone.

In some embodiments, the pH in the agrochemical zones or the root development zones is altered by a buffer.

In some embodiments, the pH in the agrochemical zones, the interface zones, and the root development zones is altered by a buffer.

The invention provides a method of growing a plant, comprising adding at least one unit of the invention to the medium in which the plant is grown.

In some embodiments, the method comprises a step of selecting the size of the unit based upon the specific plant to be grown. For example, it may be desirable to select a unit having a large swelled size when growing a plant having large diameter roots and it may be desirable to select a unit having a smaller swelled size when growing a plant having small diameter roots. In some embodiments, it may be desirable to use more units of a given size when growing a plant having a large root system than when growing a plant having a small root system.

In some embodiments, the medium in which the plant is grown comprises soil.

In some embodiments, the medium in which the plant is grown is soil.

In some embodiments, the soil comprises sand, silt, clay, or any combination thereof.

In some embodiments, the soil is clay, loam, clay-loam, or silt-loam.

In some embodiments, the soil is an Andisol.

In some embodiments, the at least one unit is added to the soil at one or more depths below the soil surface. In some embodiments, the at least one unit is added at a depth of 5-50 cm. In some embodiments, the at least one unit is added at a depth of 5 cm, 10 cm, 15 cm, 20 cm, 25 cm, 30 cm, 35 cm, 40 cm, 45 cm, or 50 cm, or any combination of 2, 3, or 4 of the foregoing depths.

The invention provides a method of reducing environmental damage caused by an agrochemical, comprising delivering the agrochemical to the root of a plant by adding at least one unit of the invention to the medium of the plant.

The present invention provides a method of minimizing exposure to an agrochemical, comprising delivering the agrochemical to the root of a plant by adding at least one unit of the invention to the medium of the plant.

In some embodiments, minimizing exposure to the agrochemical is minimizing the exposure of a farmer to the agrochemical.

In some embodiments, minimizing exposure to the agrochemical is minimizing exposure of a person other than the farmer to the agrochemical.

The present invention provides a method of generating an artificial zone with predetermined chemical properties within the root zone of a plant, comprising:

• • i) adding one or more units of the invention to the root zone of the plant; or
  • ii) adding one or more units of the invention to the anticipated root zone of the medium in which the plant is anticipated to grow.

In some embodiments, step i) comprises adding at least two different units to the root zone of the plant; and step ii) comprises adding at least two different units to the anticipated root zone of the medium in which the plant is anticipated to grow, wherein at least one of the at least two different units is a unit of the invention.

In some embodiments, each of the at least two different units contains at least one agrochemical that is not contained within one of the other at least two different units.

In some embodiments, the plant is grown in a field.

In some embodiments, the plant is a crop plant.

In some embodiments, the crop plant is a grain or a tree crop plant.

In some embodiments, the crop plant is a fruit or a vegetable plant.

In some embodiments, the plant is a banana, barley, bean, cassava, corn, cotton, grape, orange, pea, potato, rice, soybean, sugar beet, tomato, or wheat plant.

In some embodiments, the plant is a sunflower, cabbage plant, lettuce, or celery plant.

The present invention provides a method of increasing the yield of a plant, comprising (i) adding one or more units of the invention to a medium where the plant is growing or is to be grown, and (ii) growing the plant, wherein the yield of the plant is higher when grown in the medium containing the units than in the medium not containing the units.

The present invention provides a method of increasing the growth rate of a plant, comprising (i) adding one or more units of the invention to a medium where the plant is growing or is to be grown, and (ii) growing the plant, wherein the plant grows faster in the medium containing the units than in the medium not containing the units.

The present invention provides a method of increasing the size of a plant, comprising (i) adding one or more units of the invention to a medium where the plant is growing or is to be grown, and (ii) growing the plant, wherein the plant grows larger in the medium containing the units than in the medium not containing the units.

The present invention provides a method of increasing N, P, and/or K uptake by a plant, comprising (i) adding one or more units of the invention to a medium where the plant is growing or is to be grown, and (ii) growing the plant, wherein the N, P, and/or K uptake of the plant is greater in the medium containing the units than in the medium not containing the units.

The present invention provides a method of protecting a plant from low ambient temperatures, comprising (i) adding one or more units of the invention to a medium where the plant is growing or is to be grown, and (ii) growing the plant, wherein plants grown in the medium containing the units have greater survival rates under low ambient temperatures than plants grown in the medium not containing the units.

In some embodiments, low ambient temperature is below 15° C., below 12° C., below 10° C., below 8° C., below 6° C., below 4° C., below 2° C., or below 0° C.

In some embodiments, the units are added to the medium where the plant is growing.

In some embodiments, the units are added to the medium where the plant is to be grown.

In some embodiments, seeds for growing the plant are added to the medium before the units are added to the medium.

In some embodiments, seeds for growing the plant are added to the medium at the same time the units are added to the medium.

In some embodiments, seeds for growing the plant are added to the medium after the units are added to the medium.

In some embodiments, the medium is soil.

In some embodiments, the units comprise one fertilizer compound. In some embodiments, the units comprise two fertilizer compounds. In some embodiments, the units comprise three fertilizer compounds. In some embodiments, the units comprise more than three fertilizer compounds.

In some embodiments, the units comprise one to three fertilizer compounds, such that the total N, P, and/or K content as (NH₄)₂SO₂, NH₄H₂PO₄, and KCl in the medium as part of the units is about 5-50, 1-10, and 5-60 g/m², respectively.

In some embodiments, the units comprise three fertilizer compounds, such that the total N, P, and K content as (NH₄)₂SO₂, NH₄H₂PO₄, and KCl in the medium as part of the units is about 25, 5, and 30 g/m², respectively.

The invention also provides a method of making a unit of the invention comprising encapsulating at least one agrochemical zone within a SAP.

In some embodiments, encapsulating comprises polymerizing the SAP around the at least one agrochemical zone.

In some embodiments, encapsulating comprises a first polymerization step and a second polymerization step.

In some embodiments, the first polymerization step comprises forming a three dimensional structure of SAP having a cavity into which the at least one agrochemical zone can be placed, and the second polymerization step comprises sealing the cavity with additional SAP.

In some embodiments, the at least one agrochemical zone is placed in the cavity prior to the second polymerization step.

The present invention provides a bead comprising:

• • i) an external zone comprising a super absorbent polymer (SAP) that is capable of absorbing at least about 5 times its weight in water,
    • surrounding
  • ii) at least one internal zone comprising a core that contains at least one agrochemical,
    wherein the external zone is permeable to oxygen when hydrated, or the internal zone is formulated to release the at least one agrochemical into the external zone over a period of at least about one week when the hydrogel of the external zone is hydrated.

The present invention provides a bead comprising:

• • i) an external zone comprising a super absorbent polymer (SAP) that is capable of absorbing at least about 5 times its weight in water,
    • surrounding
  • ii) at least one internal zone comprising a core that contains at least one agrochemical,
    wherein the external zone is permeable to oxygen when hydrated, and the internal zone is formulated to release the at least one agrochemical into the external zone over a period of at least about one week when the hydrogel of the external zone is hydrated.

In some embodiments, the SAP is capable of absorbing at least about 50, 75, 80, 85, 90, 95, 100, 200, 300, 400, 500, or 1000 times its weight in water.

In some embodiments, the SAP is permeable to oxygen.

In some embodiments, the SAP is permeable to oxygen such that it maintains at least about 6 mg/L of dissolved oxygen in the SAP when it is hydrated.

In some embodiments, the SAP when fully hydrated is at least about 70, 75, 80, 85, 90, 95, or 100% as permeable to oxygen as hydrated alginate or hydrated semi-synthetic CMC.

In some embodiments, the SAP is an aerogel, a hydrogel or an organogel.

In some embodiments, the SAP is a hydrogel.

In some embodiments, the external zone further comprises a polymer, a porous inorganic material, a porous organic material, or any combination thereof.

In some embodiments, the internal zone further comprises an aerogel, a hydrogel, an organogel, a polymer, a porous inorganic material, a porous organic material, or any combination thereof.

In some embodiments, roots of a crop plant are capable of penetrating the hydrogel when the hydrogel is about 1%, 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 1-50% or 5-50% hydrated.

In some embodiments, roots of a crop plant are capable of penetrating the hydrogel when the hydrogel is about 1%, 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 1-50% or 5-50% hydrated.

In some embodiments, roots of a crop plant are capable of growing within the hydrogel when the hydrogel is hydrated.

In some embodiments, roots of a crop plant are capable of growing within the hydrogel when the hydrogel is about 1%, 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 1-50% or 5-50% hydrated.

In some embodiments, roots of a crop plant are capable of growing within the hydrogel when the hydrogel is hydrated.

In some embodiments, roots of a crop plant are capable of growing within the hydrogel when the hydrogel is about 1%, 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 1-50% or 5-50% hydrated.

In some embodiments, the crop plant is a sunflower plant. In some embodiments, the crop plant is a cabbage plant. In some embodiments, the crop plant is wheat plant. In some embodiments, the crop plant is maize plant. In some embodiments, the crop plant is a soybean plant. In some embodiments, the crop plant is a rice plant. In some embodiments, the crop plant is a barley plant. In some embodiments, the crop plant is a cotton plant. In some embodiments, the crop plant is a pea plant. In some embodiments, the crop plant is a potato plant. In some embodiments, the crop plant is a tree crop plant. In some embodiments, the crop plant is a vegetable plant.

In some embodiments, the hydrogel is capable of repeated swelling cycles that each comprises hydration followed by dehydration.

In some embodiments, the hydrogel is capable of repeated swelling cycles in soil that each comprise hydration followed by dehydration while in the soil.

In some embodiments, the bead is in the shape of a sphere or an equivalent polyhedron. In some embodiments, the polyhedron is six sided. In some embodiments, the polyhedron is a cube.

In some embodiments, the bead is in the shape of a sphere or an equivalent polyhedron after repeated swelling cycles.

In some embodiments, the bead is in the shape of a cylinder. In some embodiments, the bead is in the shape of a cylinder after repeated swelling cycles.

In some embodiments, the bead is in the shape of a disc.

In some embodiments, the hydrogel, when hydrated, maintains at least about 75%, 80%, 85%, 90%, or 95% of its water content over a period of at least about 25, 50, 100, or 150 hours in soil.

In some embodiments, the hydrogel, when hydrated, maintains at least about 75%, 80%, 85%, 90%, or 95% of its water content over a period of at least about 25, 50, 100, or 150 hours in sandy soil.

In some embodiments, the hydrogel, when hydrated, maintains at least about 75%, 80%, 85%, 90%, or 95% of its volume over a period of at least about 25, 50, 100, or 150 hours in soil.

In some embodiments, the hydrogel, when hydrated, maintains at least about 75%, 80%, 85%, 90%, or 95% of its volume over a period of at least about 25, 50, 100, or 150 hours in sandy soil.

In some embodiments, the hydrogel, when hydrated, maintains its shape over a period of at least about 25, 50, 100, or 150 hours in soil.

In some embodiments, the hydrogel, when hydrated, maintains spherical shape over a period of at least about 25, 50, 100, or 150 hours in sandy soil.

In some embodiments, the hydrogel, when hydrated, maintains its shape after repeated swelling cycles that each comprises hydration followed by dehydration.

In some embodiments the hydrogel, when hydrated maintains its shape after at least 3 swelling cycles that each comprises hydration followed by dehydration.

In some embodiments, the SAP is biodegradable.

In some embodiments, when hydrated in soil, the external zone of the bead has a pH or osmotic pressure that differs from the pH or osmotic pressure of the surrounding soil by at least about 10%.

In some embodiments, the external zone does not contain the at least one agrochemical before the bead is hydrated for the first time.

In some embodiments, the external zone also contains the at least one agrochemical.

In some embodiments, the amount of the at least one agrochemical in the external zone is about 5%, 10%, 15% or 20% (w/w) of the amount of the at least one agrochemical that is in the internal zone.

In some embodiments, the bead has a maximum diameter of about 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 cm when the SAP of the external zone is about 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, or 5-50% hydrated.

In some embodiments, when the SAP of the external zone is about 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, or 5-50% hydrated, the weight of the external zone is at least about 2, 3, 4, 5, 6, 7, 8, 9, or 10 times greater than the weight of the internal zone.

In some embodiments, the hydrogel is a synthetic hydrogel, a natural carbohydrate hydrogel, or a pectin or protein hydrogel, or any combination thereof.

In some embodiments, the synthetic hydrogel comprises acrylamide, an acrylic derivative, or any combination thereof.

In some embodiments, the natural carbohydrate hydrogel comprises agar, cellulose, chitosan, starch, hyaluronic acid, a dextrine, a natural gum, a sulfated polysaccharide, or any combination thereof.

In some embodiments, the pectin or protein hydrogel comprises gelatin, a gelatin derivative, collagen, a collagen derivative, or any combination thereof.

In some embodiments, the hydrogel comprises a natural super absorbent polymer (SAP), a poly-sugar SAP, a semi-synthetic SAP, a fully-synthetic SAP, or any combination thereof.

In some embodiments, the hydrogel comprises a combination of at least one natural SAP and at least one semi-synthetic or synthetic SAP.

In some embodiments, the hydrogel comprises a poly-sugar SAP.

In some embodiments, the poly-sugar SAP is alginate.

In some embodiments, the alginate is at least about 0.2% alginate.

In some embodiments, the hydrogel comprises a semi-synthetic SAP.

In some embodiments, the semi-synthetic SAP is a CMC-g-polyacrylic acid SAP.

In some embodiments, the Caboxymethyl cellulose (CMC) grafted polyacrylic acid SAP comprises 6% CMC relative to the acrylic monomers (Acrylamide-acrylic), 6% CMC relative to acrylic acid, 25% CMC relative to acrylic acid, or CMC 50% AA.

In some embodiments, the SAP is other than alginate or a k-carrageenan cross-linked-polyacrylic acid SAP.

In some embodiments, the SAP is a k-carrageenan cross-linked-polyacrylic acid SAP.

In some embodiments, the hydrogel comprises a fully synthetic SAP.

In some embodiments, the fully synthetic SAP is acrylic acid or acrylic amide or any of the combinations thereof.

In some embodiments, the external zone further comprises at least one oxygen carrier that increases the amount of oxygen in the external zone compared to a corresponding external zone not comprising the oxygen carrier.

In some embodiments, the at least one oxygen carrier is a perfluorocarbon.

In some embodiments the internal zone comprises an organic polymer, a natural polymer, or an inorganic polymer, or any combination thereof.

In some embodiments, the at least one core is coated with at least one coat compound.

In some embodiments, the at least one coat compound dissolves into the SAP when the SAP is hydrated.

In some embodiments, the at least one coat compound slows the rate at which the at least one agrochemical dissolves into the SAP when the SAP is hydrated.

In some embodiments, the at least one coat compound is silicate or silicon dioxide.

In some embodiments, the at least one coat compound is the at least one agrochemical.

In some embodiments, the at least one core comprises a polymer.

In some embodiments, the polymer is a highly cross-linked polymer.

In some embodiments, the highly cross-linked polymer is a poly-sugar or a poly-acrylic polymer.

In some embodiments, the at least one core comprises a filler.

In some embodiments, the filler comprises a cellulosic material, a cellite, a polymeric material, a silicon dioxide, a phyllosilicate, a clay mineral, metal oxide particles, porous particles, or any combination thereof.

In some embodiments, the filler comprises a phyllosilicate of the serpentine group.

In some embodiments, the a phyllosilicate of the serpentine group is antigorite (Mg₃Si₂O₅(OH)₄), chrysotile (Mg₃Si₂O₅(OH)₄), or lizardite (Mg₃Si₂O₅(OH)₄).

In some embodiments, the filler comprises a clay mineral, which is halloysite (Al₂Si₂O₅(OH)₄), kaolinite (Al₂Si₂O₅(OH)₄), illite ((K,H₃O)(Al,Mg,Fe)₂(Si,Al)₄O₁₀[(OH)₂,(H₂O)]), montmorillonite ((Na,Ca)_0.33(Al,Mg)₂Si₄O₁₀(OH)₂.nH₂O), vermiculite ((MgFe,Al)₃(Al,Si)₄O₁₀(OH)₂.4H₂O), talc (Mg₃Si₄O₁₀(OH)₂), palygorskite ((Mg,Al)₂Si₄O₁₀(OH).4(H₂O), or pyrophyllite (Al₂Si₄O₁₀(OH)₂).

In some embodiments, the filler comprises a phyllosilicate of the mica group.

In some embodiments, the a phyllosilicate of the mica group is biotite (K(Mg,Fe)₃(AlSi₃)O₁₀(OH)₂), muscovite (KAl₂(AlSi₃)O₁₀(OH)₂), phlogopite (KMg₃(AlSi₃)O₁₀(OH)₂), lepidolite (K(Li,Al)_2-3(AlSi₃)O₁₀(OH)₂), margarite (CaAl₂(Al₂Si₂)O₁₀(OH)₂), glauconite ((K,Na)(Al,Mg,Fe)₂(Si,Al)₄O₁₀(OH)₂), or any combination thereof.

In some embodiments, the filler comprises a phyllosilicate of the chlorite group.

In some embodiments, the a phyllosilicate of the chlorite group is chlorite ((Mg,Fe)₃(Si,Al)₄O₁₀(OH)₂.(Mg,Fe)₃(OH)₆).

In some embodiments, the filler forms a beehive-like structure.

In some embodiments, the beehive-like structure is microscopic.

In some embodiments, the filler comprises clay.

In some embodiments, the filler comprises zeolite.

In some embodiments, the core comprises at least about 0.05, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, or 1 grams of the at least one agrochemical. In some embodiments, the core comprises 1-10 grams of the at least one agrochemical.

In some embodiments, the core is about 30%, 35%, 40%, 45%, 50%, 55%, or 60% of the at least one agrochemical by weight.

In some embodiments, weight of the bead is 1-10 g. In some embodiments, the weight of the bead is 6-7 g. In some embodiments, the weight of the bead is 3.5-4 g.

In some embodiments, the at least one core is biodegradable.

In some embodiments, the internal zone contains one core.

In some embodiments, the internal zone contains more than one core.

In some embodiments, the at least one agrochemical is:

• • i) at least one fertilizer compound;
  • ii) at least one pesticide compound,
  • iii) at least one hormone compound;
  • iv) at least one ding compound;
  • v) at least one chemical growth agents; and/or
  • vi) at least one microelement.

In some embodiments, the at least one fertilizer compound is a natural fertilizer.

In some embodiments, the at least one fertilizer compound is a synthetic fertilizer.

In some embodiments, the at least one pesticide compound is:

• • i) at least one insecticide compound;
  • ii) at least one nematicide compound;
  • iii) at least one herbicide compound; and/or
  • iv) at least one fungicide compound.

In some embodiments, the at least one insecticide compound is imidacloprid.

In some embodiments, the at least one herbicide compound is pendimethalin.

In some embodiments, the at least one fungicide compound is azoxystrobin.

In some embodiments, the at least one nematicide compound is fluensulfone.

In some embodiments, the at least one fertilizer compound is PO₄, NO₃, (NH₄)₂SO₂, NH₄H₂PO₄, and/or KCl.

In some embodiments, the at least one fertilizer compound comprises multiple fertilizer compounds which include PO₄, NO₃, (NH₄)₂SO₂, NH₄H₂PO₄, and/or KCl.

In some embodiments, the at least one agrochemical is at least one fertilizer compound and at least one pesticide compound.

In some embodiments, the at least one agrochemical is at least one pesticide compound.

In some embodiments, the at least one agrochemical is at least one fertilizer compound.

In some embodiments, the at least one pesticide compound is at least one pesticide compound that is not suitable for application to an agricultural field.

In some embodiments, the at least one pesticide compound that is not suitable for application to an agricultural field is too toxic to be applied to an agricultural field.

In some embodiments, the at least one pesticide compound is toxic to animals other than arthropods or mollusks when applied to an agricultural field in an amount that is sufficient to kill an arthropod or a mollusk.

In some embodiments, the at least one agrochemical is released from the core of the internal zone over a period of at least about one week when the SAP of the external zone is hydrated.

In some embodiments, the at least one agrochemical is released from the core of the internal zone over a period of at least about one week when the SAP of the external zone is hydrated.

In some embodiments, the at least one agrochemical is released from the internal zone into the external zone over a period of at least about 2, 3, 4, 5, 6, 7, 8, 9, 10, or 20 weeks when the SAP of the external zone is hydrated.

In some embodiments, the at least one agrochemical is released from the internal zone into the external zone over a period of at least about 2, 3, 4, 5, 6, 7, 8, 9, 10, or 20 weeks when the SAP of the external zone is about 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, or 5-50% hydrated.

In some embodiments, when the SAP of the bead is hydrated and the bead is in soil, the at least one agrochemical diffuses from the surface of the bead into the surrounding soil at a linear rate beginning about 25 days after hydration.

In some embodiments, when the SAP of the bead is hydrated and the bead is in soil, the at least one agrochemical diffuses from the surface of the bead into the surrounding soil for at least about 50 or 75 days after hydration.

In some embodiments, the bead is not hydrated.

In some embodiments, the bead contains less than about 35%, 30%, 25%, 20%, 15%, or 10% water by weight.

In some embodiments, the bead further comprises an interface zone between the internal zone and the external zone, which interface zone is formed by at least one insoluble salt or solid, at least one cross-linking agent, or at least one inorganic compound.

In some embodiments, diffusion between the external zone and the internal zone is limited by altering the pH or the cation concentration in the internal zone, the external zone, or the interface zone.

In some embodiments, diffusion between the external zone and the internal zone is limited by altering the pH and/or cation concentration in the internal zone or the external zone.

In some embodiments, the pH in the internal zone or the external zone is altered by a buffer.

In some embodiments, the pH in the internal zone, the external zone, or the interface zone is altered by a buffer.

The present invention provides a method of growing a plant, comprising adding at least one bead of the invention to the medium in which the plant is grown.

In some embodiments, the medium in which the plant is grown comprises soil.

In some embodiments, the medium in which the plant is grown is soil.

In some embodiments, the soil comprises sand, silt, clay, or any combination thereof.

In some embodiments, the soil is clay, loam, clay-loam, or silt-loam.

The present invention provides a method of growing a plant, comprising adding multiple beads of the invention to the medium of the plant, wherein the multiple beads comprise three fertilizer compounds, such that the total N, P, and K content as (NH₄)₂SO₂, NH₄H₂PO₄, and KCl in the medium as part of the beads is about 25, 5, and 30 g/m², respectively.

The present invention provides a method of generating an artificial zone with predetermined chemical properties within the root zone of a plant, comprising:

• • i) adding at least two different beads to the root zone of the plant; or
  • ii) adding at least two different beads to the anticipated root zone of the medium in which the plant is anticipated to grow,
    wherein at least one of the at least two different beads is a bead of an embodiment of the invention.

In some embodiments, each of the at least two different beads contains at least one agrochemical that is not contained within one of the other at least two different of beads.

In some embodiments, the plant is grown in a field.

In some embodiments, the plant is a crop plant. In some embodiments, the crop plant is a grain or a tree crop plant. In some embodiments, the crop plant is a fruit or a vegetable plant.

In some embodiments, the plant is a banana, barley, bean, cassava, corn, cotton, grape, orange, pea, potato, rice, soybean, sugar beet, tomato, or wheat plant.

The present invention provides an artificial environment for plant growth comprising two parts, wherein part A forms a continuous system with part B, whereas;

• • Part A is a controlled release reservoir of additive with a weight of at least 0.05 gr, and wherein;
  • Part B is an artificial environment comprised of at least 90% water when fully swelled, and its weight is at least 5 times larger than part A.

The present invention provides an artificial environment for plant growth comprising two parts, wherein part A is located inside part B, whereas;

• • Part A is a controlled release reservoir of additive with a weight of at least 0.05 gr, and wherein;
  • Part B is a artificial environment comprised of at least 90% water when fully swelled, and its weight is at least 5 times larger than part A.

In some embodiments, the artificial environment is synthesized so that one of the moisture, pH or osmotic pressure inside the artificial environment is different by at least 10% from the surrounding soil; and plant roots can penetrate and grow inside the artificial environment volume.

In some embodiments, parts A and B are fabricated from materials consisting of polymers, aerogels, hydrogels, organogels, porous inorganic, porous organic material or a combination thereof.

In some embodiments, part A is selected from the group consisting of organic polymer, natural polymer, inorganic polymer or a combination thereof.

In some embodiments, part A also comprises components in the solids form.

In some embodiments, part A contains fillers selected from the group consisting from clays, metal oxide particles, porous particles or a combination thereof.

In some embodiments, additive is selected from the group consisting of nutrients, agrochemicals, pesticides, microelements, drugs or a combination thereof.

In some embodiments, part A comprises both structural materials and functional materials.

In some embodiments, part B contains no fraction of said additive, or at least 10 times lower concentration of said additives then in Part A, when added to the soil.

In some embodiments, part B is selected from the group consisting of organic polymer, natural polymer, inorganic polymer or a combination thereof.

In some embodiments, part B contains fillers selected from the group consisting from air, porous particles or a combination thereof.

In some embodiments, the artificial environment is transported to the field in a dry form, containing less than 30% water.

In some embodiments, the dimension of the artificial environment is at least 30 mL in the fully swelled form.

In some embodiments, the additive concentration in Part A is at least 50%.

In some embodiments, after contacting Part A and Part B, an interface is formed between the two parts by means of: the formation of insoluble salts or solids, cross linking agents, inorganic component chemistry or by altering pH or cation concentration so as to limit the diffusion between the two parts and the combination thereof.

In some embodiments, part A also comprises components in the solids form.

In some embodiments, part A comprises both structural materials and functional materials.

In some embodiments, the distance between the artificial environment and the plant seed is between 0.1 to 500 centimeters.

In some embodiments, the distance between the artificial environment and the plant seed is between 0.1 to 500 centimeters. In some embodiments, the distance between the artificial environment and the plant seed is about 0.5, 1, 15, 2, 2.5, 3, 3.5, 4, 4.5, 5, 5.5, 6, 6.5, 7, 7.5, 8, 8.5, 9, 9.5, 10, 15, 20, 25, 30, 35, 40, 45, 50, or 100 centimeters.

Non-limiting examples of structural materials of the present invention are materials that give the structure of the system for example water, aerogels, treated starch, treated cellulose, polymers, superadsorbents and the functional materials are the materials consumed by the plant for example, a fertilizer compound.

Each embodiment disclosed herein is contemplated as being applicable to each of the other disclosed embodiments. Thus, all combinations of the various elements described herein are within the scope of the invention.

It is understood that where a parameter range is provided, all integers within that range, and tenths thereof, are also provided by the invention. For example, “0.2-5 mg/kg/day” is a disclosure of 0.2 mg/kg/day, 0.3 mg/kg/day, 0.4 mg/kg/day, 0.5 mg/kg/day, 0.6 mg/kg/day etc. up to 5.0 mg/kg/day.

Terms

Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by a person of ordinary skill in the art to which this invention belongs.

As used herein, and unless stated otherwise or required otherwise by context, each of the following terms shall have the definition set forth below.

As used herein, “about” in the context of a numerical value or range means ±10% of the numerical value or range recited or claimed, unless the context requires a more limited range.

An “agrochemical zone” is a component of a unit of the invention which contains at least one agrochemical and which releases the at least one agrochemical into the root development zones of a unit of the invention. In some embodiments, the at least one agrochemical is released into the root development zones of a unit of the invention by diffusion when the root development zones of the unit are hydrated.

The term “coating system” means one or more compounds which delays or prevents the release of an agrochemical from the surface of an agrochemical zone which is covered by the coating system. In some embodiments, the coating system comprises a single coat compound. In some embodiments, the coating system comprises more than one coat compound. In some embodiments, the coating system comprises more than one layer. In some embodiments, each layer of the coating system is of the same composition. In some embodiments, each layer of the coating composition is of a different composition. In some embodiments, the coating system comprises two, three, or four layers.

The term “controlled release” when used to refer to an agrochemical zone means that the agrochemical zone is formulated to release the one or more agrochemicals of the agrochemical zone gradually over time. In some embodiments, the agrochemical zones are formulated to release the at least one agrochemical into the root development zones over a period of at least about one week when the root development zones are hydrated. In some embodiments, the agrochemical zones are formulated to release the at least one agrochemical into the root development zones over a period greater than one week when the root development zones are hydrated. “Controlled release” is interchangeable with the term “slow release” (“SR”).

“DAP” means days after planting.

Unless required otherwise by context, a “unit” refers to a unit for delivery of agrochemicals to the roots of a plant as described herein. A “fertilizer unit” refers to a unit for delivery of agrochemicals to the roots of a plant as described herein which comprises a fertilizer.

An “empty unit” comprises the root development zone component of a unit of the invention unaccompanied by the agrochemical zone component. In some embodiments, an empty unit has the same shape and/or dimensions as the corresponding unit of the invention.

A “root development zone” is a component of a unit of the invention which, when hydrated, can be penetrated by a growing root. In some embodiments, the growing root can grow and develop within the root development zone of a unit. In some embodiments, a root development zone is a super absorbent polymer (SAP). In some embodiments, the root development zone is an aerogel, a geotextile, or a sponge. In some embodiments, the root development zone will take up water from the surrounding environment when, for example, the unit is placed in soil which is subsequently irrigated. In some embodiments, the hydrated root development zones create a artificial environment in which a growing root can uptake water and nutrients. In some embodiments, the root development zones of a unit are formulated to contain one or more agrochemicals which are the same or different than the agrochemicals of the agrochemical zones of the unit. While the invention described herein is not limited to any particular mechanism of action, it is believed that a growing root is attracted to the root development zones of a unit because of the presence of water and/or agrochemicals (e.g. minerals) in the root development zones. It is believed that roots can continue to grow and develop within the root development zones of units because of the continued availability of water and/or agrochemicals in the units.

Use of the term “root development zones” means one or more root development zones and use of the term “agrochemical zones” means one or more agrochemical zones unless stated otherwise or required otherwise by context.

In some embodiments, a unit of the invention is in the form of a “bead” having an “external zone” which surrounds an “internal zone.” In some embodiments, the “external zone” is a root development zone and the “internal zone” is an agrochemical zone.

Plants provided by or contemplated for use in embodiments of the present invention include both monocotyledons and dicotyledons. In some embodiments, a plant is a crop plant. As used herein, a “crop plant” is a plant which is grown commercially. In some embodiments, the plants of the present invention are crop plants (for example, cereals and pulses, maize, wheat, potatoes, tapioca, rice, sorghum, millet, cassava, barley, or pea), or other legumes. In some embodiments, the crop plants may be grown for production of edible roots, tubers, leaves, stems, flowers or fruit. The plants may be vegetable or ornamental plants. Non-limiting examples of crop plants of the invention include: Acrocomia aculeata (macauba palm), Arabidopsis thaliana, Aracinis hypogaea (peanut), Astrocaryum murumuru (murumuru), Astrocaryum vulgare (tucumã), Attalea geraensis (Indaiá-rateiro), Attalea humilis (American oil palm), Attalea oleifera (andaiá), Attalea phalerata (uricuri), Attalea speciosa (babassu), Avena sativa (oats), Beta vulgaris (sugar beet), Brassica sp. such as Brassica carinata, Brassica juncea, Brassica napobrassica, Brassica napus (canola), Camelina sativa (false flax), Cannabis sativa (hemp), Carthamus tinctorius (safflower), Caryocar brasiliense (pequi), Cocos nucifera (Coconut), Crambe abyssinica (Abyssinian kale), Cucumis melo (melon), Elaeis guineensis (African palm), Glycine max (soybean), Gossypium hirsutum (cotton), Helianthus sp. such as Helianthus annuus (sunflower), Hordeum vulgare (barley), Jatropha curcas (physic nut), Joannesia princeps (arara nut-tree), Lemna sp. (duckweed) such as Lemna aequinoctialis, Lemna disperma, Lemna ecuadoriensis, Lemna gibba (swollen duckweed), Lemna japonica, Lemna minor, Lemna minuta, Lemna obscura, Lemna paucicostata, Lemna perpusilla, Lemna tenera, Lemna trisulca, Lemna turionifera, Lemna valdiviana, Lemna yungensis, Licania rigida (oiticica), Linum usitatissimum (flax), Lupinus angustifolius (lupin), Mauritia flexuosa (buriti palm), Maximiliana maripa (inaja palm), Miscanthus sp. such as Miscanthus×giganteus and Miscanthus sinensis, Nicotiana sp. (tabacco) such as Nicotiana tabacum or Nicotiana benthamiana, Oenocarpus bacaba (bacaba-do-azeite), Oenocarpus bataua (patauã), Oenocarpus distichus (bacaba-de-leque), Oryza sp. (rice) such as Oryza sativa and Oryza glaberrima, Panicum virgatum (switchgrass), Paraqueiba paraensis (mari), Persea amencana (avocado), Pongamia pinnata (Indian beech), Populus trichocarpa, Ricinus communis (castor), Saccharum sp. (sugarcane), Sesamum indicum (sesame), Solanum tuberosum (potato), Sorghum sp. such as Sorghum bicolor, Sorghum vulgare, Theobroma grandifrum (cupuassu), Trifolium sp, Trithrinax brasiliensis (Brazilian needle palm), Triticum sp. (wheat) such as Triicum aestivum, Zea mays (corn), alfalfa (Medicago sativa), rye (Secale cerale), sweet potato (Lopnoea batatus), cassava (Manihot esculenta), coffee (Cofea spp.), pineapple (Anana comosus), citris tree (Citrus spp.), cocoa (Theobroma cacao), tea (Camellia senensis), banana (Musa spp.), avocado (Persea americana), fig (Ficus casica), guava (Psidium guajava), mango (Mangifer indica), olive (Olea europaea), papaya (Carica papaya), cashew (Anacardium occidentale), macadamia (Macadamia intergrifolia) and almond (Prunus amygdalus).

Unless stated otherwise or required otherwise by context, “swelled” means that a material has an absorbed amount of water which is at least about 1% of the amount of water that would be absorbed by the material if placed in deionized water for 24 hours at 21° C. When the material is a hydrogel, a “swelled” hydrogel can be referred to as a “hydrated” hydrogel. In some embodiments, a swelled material has an absorbed amount of water which is at least about 2% of the amount of water that would be absorbed by the material if placed in deionized water for 24 hours at 21° C. In some embodiments, a swelled material has an absorbed amount of water which is at least about 3% of the amount of water that would be absorbed by the material if placed in deionized water for 24 hours at 21° C. In some embodiments, a swelled material has an absorbed amount of water which is at least about 4% of the amount of water that would be absorbed by the material if placed in deionized water for 24 hours at 21° C. In some embodiments, a swelled material has an absorbed amount of water which is at least about 5% of the amount of water that would be absorbed by the material if placed in deionized water for 24 hours at 21° C.

Unless stated otherwise or required otherwise by context, “hydrated” means at least about 1% hydrated. In some embodiments, “hydrated” means at least about 2% hydrated. In some embodiments, “hydrated” means at least about 3% hydrated. In some embodiments, “hydrated” means at least about 4% hydrated. In some embodiments, “hydrated” means at least about 5% hydrated.

As used herein, a “fully swelled” unit of the invention is a unit which contains an amount of absorbed water which is equal to the amount of water the unit would absorb if placed in deionized water for 24 hours at 21° C.

As used herein, an artificial environment means a media located within the root zone of an agricultural field or a garden plant loaded with at least one agrochemical, encourages root growth and uptake activity within its internal periphery. Non-limiting examples of agrochemicals include pesticides, including insecticides, herbicides, and fungicides. Agrochemicals may also include natural and synthetic fertilizers, hormones and other chemical growth agents.

In some embodiments, the medium may comprise multiple sub-zones, such as:

• • i) an agrochemical zone (for example, an Internal Zone); and
  • ii) a root development zone (for example, an External Zone).

In some embodiments, the agrochemical zone is formulated to release the at least one agrochemical into the root development zone over a period of at least about one week when the hydrogel of the root development zone is hydrated. In some embodiments, the agrochemical zone is formulated to release the at least one agrochemical into the root development zone over a period of at least about 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, or 20 weeks when the hydrogel of the root development zone is hydrated. The agrochemical zone may be formulated to control the release of the at least one agrochemical into the root development zone by a variety of means described herein. For example, the at least one agrochemical may be incorporated into a dense polymer in the core of the agrochemical zone, from which the at least one agrochemical diffuses when root development zone is hydrated. Additionally, the core may be coated with a compound or compounds that slow the rate of the at least one agrochemical's diffusion into the root development zone. In some embodiments, the coat compound may diffuse into the root development zone when the root development zone is hydrated, thereby slowing the rate of the at least one agrochemical's diffusion into and/or through the root development zone. In some embodiments, the core comprises a filler comprising the at least one agrochemical, from which the at least one agrochemical diffuses. In some embodiments, the at least one agrochemical diffuses from the core or the filler at a linear rate. The filler may slow the rate of the at least one agrochemical from the core. In some embodiments filler may has a physical structure, such as a beehive-like structure, into which the at least one agrochemical is incorporated, and from which the at least one agrochemical slowly diffuses. Bentonite is a non-limiting example of a filler having a beehive-like structure that is useful in embodiments of the present invention.

The agrochemical zone may contain the input (fertilizer or other agrochemical) in a structure that controls its release into the root development zone. The release rate is designed to meet plant demands throughout the growing season. In some embodiments, no input residuals remain at the end of a predetermined action period.

In some embodiments, the agrochemical zone comprises one or more fertilizers and/or other agrochemicals such as nitrogen, phosphorus, potassium, fungicide, insecticide, etc., in a beehive like structure made from highly cross linked polymer coated with silica or highly cross linked poly acrylic acid/poly sugar with a clay filler. In some embodiments, the agrochemical zone comprises fertilizer and/or at least one other agrochemical in a beehive like structure with or without an external coating.

In some embodiments, the root development zone is a super absorbent polymer (SAP) in contact with or surrounding the agrochemical zone, which attracts the growth and uptake activity of plant roots. In some embodiments, the root development zone is a super absorbent polymer-made from CMC-g-poly(acrylic acid)/celite composite system or modified corn starch cross linked poly (acrylic acid). A root development zone which surrounds an agrochemical zone may be referred to herein as a “shell.”

Root development zones of the present invention are sustainable in soils, and encourage root penetration, uptake activity, and growth and/or development in the root development zone. In some embodiments, a super absorbent polymer may serve as the root development zone since during watering it can absorb soil moisture, swell and maintain its high water content over long period of time. These features establish a zone where gradual transition of chemical concentration exists between the agrochemical zone to the periphery of the root development zone allowing root uptake activity during the unit of the invention's life cycle. In some embodiments, the root development zone has features such as mechanical resistance (in order to maintain its shape and geometry in the soil); swelling cycle capability (capable of repeated hydration and dehydration in response to soil water content); oxygen permeability—(maintaining sufficient oxygen level to support root activity, such as root development); and root penetration (allowing the growth of roots into it).

Materials that may be used in the present invention include but are not limited to: 1) clay 2) zeolite 3) tuff 4) fly ash 5) hydrogel 6) foam.

In some embodiments, an artificial environment of the present invention serves as a buffer for soil type and pH to provide universal root growth environment. In some embodiments, an artificial environment of the present invention contains needed materials and nutrients in the desired conditions, such as but not limited to water, fertilizers, drugs, and other additives.

Oxygen Permeability

Aspects of the present invention relate to root development zones having SAPs that are permeable to oxygen when hydrated. Roots use oxygen for growth and development (Drew, 1997; Hopkins 1950). Therefore, the oxygen permeability of a SAP is an important factor in determining whether it will support root growth and development within a root development zone that comprises the SAP.

Without wishing to be bound by any scientific theory, since hydrogels of the present invention supply water, nutrients and weak resistance, the data hereinbelow show that provided the gas diffusion is high enough, roots will develop in most types of small-volume hydrogels and hydrogel containing units, installed in a field soil. For example, alginate hydrogel, which is suitably permeable to oxygen, encourages root development, whereas starch hydrogel, which is poorly permeable to oxygen does not encourage root development. Additionally, semi-synthetic CMC is also suitably permeable to oxygen. The ability of oxygen to diffuse into root development zones of the present invention is important for root development within them.

Aspects of the present invention relate to the selection of SAPs, such as hydrogels, that are sufficiently permeable to oxygen when hydrated. Oxygen permeability may be measured to determine whether a hydrated SAP is sufficiently permeable to oxygen for use in embodiments of the present invention. In some embodiments, the SAP is permeable to oxygen such that it supports root growth and/or development. In some embodiments, the SAP when hydrated is at least about 70, 75, 80, 85, 90, 95, or 100% as permeable to oxygen as hydrated alginate. In some embodiments, the SAP when hydrated is at least about 70, 75, 80, 85, 90, 95, or 100% as permeable to oxygen as hydrated semi-synthetic CMC.

Oxygen permeability may be measured according to assays that are well known in the art. Non-limiting examples of methods that may be useful for measuring oxygen permeability of SAPs of the invention are described in Aiba et al. (1968) “Rapid Determination of Oxygen Permeability of Polymer Membranes” Ind. Eng. Chem. Fundamen., 7(3), pp 497-502; Yasuda and Stone (1962) “Permeability of Polymer Membranes to Dissolved Oxygen” Cedars-Sinai Medical Center Los Angeles Calif. Polymer Div, 9 pages, available from www.dtic.mil/cgi-bin/GetTRDoc?Location=U2&doc=GetTRDoc.pdf&AD=AD0623983; Erol Ayranci and Sibel Tune (March 2003) “A method for the measurement of the oxygen permeability and the development of edible films to reduce the rate of oxidative reactions in fresh foods” Food Chemistry Volume 80, Issue 3, Pages 423-431; and Compañ et al. (July 2002) “Oxygen permeability of hydrogel contact lenses with organosilicon moieties” Biomaterials Volume 23, Issue 13, Pages 2767-2772, the entire contents of each of which are incorporated herein by reference. The permeability of a SAP may be measured when it is partially or fully hydrated, e.g. when the SAP is 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, or 5-50% hydrated.

Mechanical Resistance

In preferred embodiments of the present invention, the root development zones of a unit of the invention are both i) sufficiently permeable to oxygen to encourage root growth, and ii) do not disintegrate in soil. In especially preferred embodiments, the root development zones of a unit of the invention are mechanically resistant, i.e., are capable of repeated swelling cycles in soil without fragmenting in the soil. In particularly preferred embodiments, all of the SAP of the root development zones remains part of the root development zones after repeated swelling cycles.

Despite alginate's permeability to oxygen, root development zones consisting of alginate are not suitable in preferred embodiments of the invention because alginate tends to disintegrate in soil. However, semi-synthetic CMC, which does not tend to disintegrate and is capable of repeated swelling cycles without fragmenting in soil (i.e., is mechanically resistant), is suitable for use in root development zones in preferred embodiments the invention.

Implementation of Artificial Environments

Some embodiments of the present invention comprise the following phases:

Phase 1: Banding and incorporating into the upper soil profile.

Phase 2: Following watering (rainfall and/or irrigation) the root development zones (comprising, e.g. a SAP) absorbs moisture from the soil and swells; water penetrates the coating (if present) and dissolves the fertilizer and/or other agrochemical(s) which then diffuse into the root development zones (e.g. towards the periphery of a bead).

Phase 3: Roots grow, develop, and remain in the root development zones where uptake lasts a predetermined period.

Methods for Testing Properties of Root Development Zones

The following is a non-limiting example of a method that may be used to test the properties of root development zones (e.g. bead shells).

• • Distribute empty units (e.g. shells) of different sizes in a pot. In some embodiments, empty units of three sizes are used. The shells may have a dry radius of, e.g., 0.5, 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, or 5 cm or a length of, e.g., 0.5, 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5, 6, 7, 8, 9, or 10 cm. In some embodiments a 10, 11, 12, 13, 14, 15, 20, 25, or 30 liter pot is used. In some embodiments the empty units are distributed in the pot with soil. In some embodiments, the soil is sandy soil.
  • Monitor the final size and geometry of the empty units following watering. In some embodiments, the final geometry is spherical, cylindrical, or box shaped.
  • Installing ceramic suction cups to mimic roots water uptake and applying suction through the syringes.
  • Altering watering frequency over time (e.g., from high—few times per day to low—once a week).
  • Monitoring the volume of water in the syringes and water drained from the bottom of the pot over time.

The following is another non-limiting example of a method that may be used to test the properties of root development zones (e.g. bead shells),

• • Distribute empty units (e.g. shells) of one size (base, e.g. on findings from the method described above phase) in a transparent cell. In some embodiments, the cell is made of Perspex- and is 60×2×30 cm). In some embodiments, the empty units are distributed with soil. In some embodiments, the soil is sandy soil.
  • Monitoring root location and empty unit status. In some embodiments, root location and empty status is monitored by photography or/and scanning.
  • Repeat with units with/without nutrients.
  • Monitoring roots location to conclude if roots attract by nutrients or water.
  • Altering watering frequency over time (e.g., from high—few times per day to low—once a week).

Methods for Testing Properties of Units of the Invention

The following is a non-limiting example of a method that may be used to test the properties of root development zones (e.g. bead shells).

• • Growing a plant in a pot. In some embodiments, the pot is a 10, 11, 12, 13, 14, 15, 20, 25, or 30 liter pot.
  • Installing filter paper cups to monitor concentrations in the root zone and drainage over time.

Additionally:

• • Growing a plant in a transparent cell with mixture of units (e.g. beads) and soil. In some embodiments, the soil is sandy soil.
  • Add dying agents to units which are sensitive to environmental conditions (e.g., pH, Salinity, or N, P, and K).
  • Altering watering frequency over time (e.g. from high—few times per day to low—once a week).

Super Absorbent Polymers

Super Absorbent Polymers are polymers that can absorb and retain extremely large amounts of a liquid relative to their own mass. Non-limiting examples of SAPs that are useful in embodiments of the subject invention are described in K. Horie, M. Bairon, R. B. Fox, J. He, M. Hess, J. Kahovec, T. Kitayama, P. Kubisa, E. Maréchal, W. Mormann, R. F. T. Stepto, D. Tabak, J. Vohlídal, E. S. Wilks, and W. J. Work (2004). “Definitions of terms relating to reactions of polymers and to functional polymeric materials (IUPAC Recommendations 2003)”. Pure and Applied Chemistry 76 (4): 889-906; Kabiri, K. (2003). “Synthesis of fast-swelling superabsorbent hydrogels: effect of crosslinker type and concentration on porosity and absorption rate”. European Polymer Journal 39 (7): 1341-1348; “History of Super Absorbent Polymer Chemistry”. M2 Polymer Technologies, Inc. (available from www.m2polymer.com/html/history_of_superabsorbents.html); “Basics of Super Absorbent Polymer & Acrylic Acid Chemistry”. M2 Polymer Technologies, Inc. (available from www.m2polymer.com/html/chemistry_sap.html); Katime Trabanca, Daniel; Katime Trabanca, Oscar; Katime Amashta, Issa Antonio (September 2004). Los materiales inteligentes de este milenio: Los hidrogeles macromoleculares. Sintesis, propiedades y aplicaciones. (1 ed.). Bilbao: Servicio Editorial de la Universidad del País Vasco (UPVIEHU); and Buchholz, Fredric L; Graham, Andrew T, ed. (1997). Modern Superabsorbent Polymer Technology (1 ed.), John Wiley & Sons, the entire contents of each of which are hereby incorporated herein by reference.

Non-limiting examples of hydrogels that are useful in embodiments of the subject invention are described in Mathur et al., 1996. “Methods for Synthesis of Hydrogel Networks: A Review” Journal of Macromolecular Science, Part C: Polymer Reviews Volume 36, Issue 2, 405-430; and Kabiri et al., 2010. “Superabsorbent hydrogel composites and nanocomposites: A review” Volume 32, Issue 2, pages 277-289, the entire contents of each of which are hereby incorporated herein by reference.

Geotextiles

Geotextiles are permeable fabrics which are typically used to prevent the movement of soil or sand when placed in contact with the ground. Non-limiting examples of geotextiles that are useful in embodiments of the subject invention are described in U.S. Pat. Nos. 3,928,696, 4,002,034, 6,315,499, 6,368,024, and 6,632,875, the entire contents of each of which are hereby incorporated herein by reference.

Aerogels

Aerogels are gels formed by the dispersion of air in a solidified matrix. Non-limiting examples of aerogels that are useful in embodiments of the subject invention are described in Aegerter, M., ed. (2011) Aerogels Handbook. Springer, the entire contents of which is hereby incorporated herein by reference.

Aerochemicals

Fertilizers

A fertilizer is any organic or inorganic material of natural or synthetic origin (other than liming materials) that is added to a plant medium to supply one or more nutrients that promotes growth of plants.

Non-limiting examples of fertilizers that are useful in embodiments of the subject invention are described in Stewart, W. M.; Dibb, D. W.; Johnston, A. E.; Smyth, T. J. (2005). “The Contribution of Commercial Fertilizer Nutrients to Food Production”. Agronomy Journal 97: 1-6.; Erisman, Jan Willem; MA Sutton, J Galloway, Z Klimont, W Winiwarter (October 2008). “How a century of ammonia synthesis changed the world” Nature Geoscience 1 (10): 636.; G. J. Leigh (2004). The world's greatest fix: a history of nitrogen and agriculture. Oxford University Press US, pp. 134-139; Glass, Anthony (September 2003). “Nitrogen Use Efficiency of Crop Plants: Physiological Constraints upon Nitrogen Absorption”. Critical Reviews in Plant Sciences 22 (5): 453; Vance; Uhde-Stone & Allan (2003), “Phosphorus acquisition and use: critical adaptations by plants for securing a non renewable resource”. New Phythologist (Blackwell Publishing) 157 (3): 423-447.; Moore, Geoff (2001). Soilguide—A handbook for understanding and managing agricultural soils. Perth, Western Australia: Agriculture Western Australia. pp. 161-207; Hitussinger, Peter; Reiner Lohmiiller, Allan M. Watson (2000). Ullmann's Encyclopedia of Industrial Chemistry, Volume 18. Weinheim, Germany: Wiley-VCH Verlag GmbH & Co. KGaA. pp. 249-307.; Carroll and Salt, Steven B. and Steven D. (2004). Ecology for Gardeners. Cambridge: Timber Press.; Enwall, Karin; Laurent Philippot, 2 and Sara Hallin1 (December 2005). “Activity and Composition of the Denitrifying Bacterial Community Respond Differently to Long-Term Fertilization”. Applied and Environmental Microbiology (American Society for Microbiology) 71 (2): 8335-8343.; Birkhofera, Klaus; T. Martijn Bezemerb, c, d, Jaap Bloeme, Michael Bonkowskia, Søren Christensenf, David Duboisg, Fleming Ekelundf, Andreas Flieβbachh, Lucie Gunstg, Katarina Hedlundi, Paul Mäderh, Juha Mikolaj, Christophe Robink, Heikki Setäläj, Fabienne Tatin-Frouxk, Wim H. Van der Puttenb, c and Stefan Scheua (September 2008). “Long-term organic farming fosters below and aboveground biota: Implications for soil quality, biological control and productivity”. Soil Biology and Biochemistry (Soil Biology and Biochemistry) 40 (9): 2297-2308.; Lal, R. (2004). “Soil Carbon Sequestration Impacts on Global Climate Change and Food Security”. Science (Science (journal)) 304 (5677): 1623-7.; and Zublena, J. P.; J. V. Baird, J. P. Lilly (June 1991). “SoilFacts—Nutrient Content of Fertilizer and Organic Materials”. North Carolina Cooperative Extension Service. (available from www.soil.ncsu.edu/publications/Soilfacts/AG-439-18/), the entire contents of each of which are hereby incorporated herein by reference.

Non-limiting examples of fertilizers which may be useful in embodiments of the present invention include Ammonium nitrate, Ammonium sulfate, anhydrous ammonia, calcium nitrate/urea, oxamide, potassium nitrate, urea, urea sulfate, ammoniated superphosphate, diammonium phosphate, nitric phosphate, potassium carbonate, potassium metaphosphate, calcium chloride, magnesium ammonium phosphate, magnesium sulfate, ammonium sulfate, potassium sulfate, and others disclosed herein.

Pesticides

Pesticides are substances or mixtures of substances capable of preventing, destroying, repelling or mitigating any pest. Pesticides include insecticides, nematicides, herbicides and fungicides.

Insecticides

Insecticide are pesticides that are useful against insects, and include but are not limited to organochloride, organophosphate, carbamate, pyrethroid, neonicotinoid, and ryanoid, insecticides.

Non-limiting examples of insecticides that are useful in embodiments of the subject invention are described in van Emden H F, Pealall D B (1996) Beyond Silent Spring, Chapman & Hall, London, 322 pp; Rosemary A. Cole “Isothiocyanates, nitriles and thiocyanates as products of autolysis of glucosinolates in Cruciferae” Phytochemutry, 1976. Vol. 15, pp. 759-762; and Robert L. Metcalf “Insect Control” in Ullmann's Encyclopedia of Industrial Chemistry” Wiley-VCH, Weinheim, 2002, the entire contents of each of which are incorporated herein by reference.

Nematicides

Nematicides are pesticides that are useful against plant-parasitic nematodes.

Non-limiting examples of nematicides that are useful in embodiments of the subject invention are described in D. J. Chitwood, “Nematicides,” in Encyclopedia of Agrochemicals (3), pp. 1104-1115, John Wiley & Sons, New York, N.Y., 2003; and S. R. Gowen, “Chemical control of nematodes: efficiency and side-effects,” in Plant Nematode Problems and their Control in the Near East Region (FAO Plant Production and Protection Paper—144), 1992, the entire contents of each of which are incorporated herein by reference.

Herbicides

Herbicides are pesticides that are useful against unwanted plants. Non-limiting examples of herbicides that are useful in embodiments of the subject invention include 2,4-D, aminopyralid, atrazine, clopyralid, dicamba, glufosinate ammonium, fluazifop, fluroxypyr, imazapyr, imazamox, metolachlor, pendimethalin, picloram, and triclopyr.

Fungicides

Fungicides are pesticides that are useful against fungi and/or fungal spores.

Non-limiting examples of fungicides that are useful in embodiments of the subject invention are described in Pesticide Chemistry and Bioscience edited by G. T Brooks and T. R Roberts. 1999. Published by the Royal Society of Chemistry; Metcalfe, R. J. et al. (2000) The effect of dose and mobility on the strength of selection for DMI (sterol demethylation inhibitors) fungicide resistance in inoculated field experiments. Plant Pathology 49: 546-557; and Sierotzki, Helge (2000) Mode of resistance to respiration inhibitors at the cytochrome bc1 enzyme complex of Mycosphaerella fijiensis field isolates Pest Management Science 56:833-841, the entire contents of each of which are incorporated herein by reference.

Microelements

Non-limiting examples of microelements that are useful in embodiments of the subject invention include iron, manganese, boron, zinc, copper, molybdenum, chlorine, sodium, cobalt, silicon, and selenium nickel.

Hormones

Plant hormones may be used to affect plant processes.

Non-limiting examples of plant hormones that are useful in embodiments of the subject invention include but are not limited to, auxins (such as heteroauxin and its analogues, indolylbutyric acid and a-naphthylacetic acid), gibberellins, and cytokinins.

All publications and other references mentioned herein are incorporated by reference in their entirety, as if each individual publication or reference were specifically and individually indicated to be incorporated by reference. Publications and references cited herein are not admitted to be prior art.

This invention will be better understood by reference to the Experimental Details which follow, but those skilled in the art will readily appreciate that the specific experiments detailed are only illustrative of the invention as defined in the claims which follow thereafter.

EXPERIMENTAL DETAILS

Examples are provided below to facilitate a more complete understanding of the invention. The following examples illustrate the exemplary modes of making and practicing the invention. However, the scope of the invention is not limited to specific embodiments disclosed in these Examples, which are for purposes of illustration only.

Example 1

The External Zone

Four specific criteria were defined as the following, where each condition was tested experimentally:

• • Mechanical resistance—maintain shape and geometry in the soil
  • Swelling cycles—hydrate and dehydrate in corresponds to soil water content
  • Oxygen permeability—maintain sufficient oxygen level to root activity
  • Root penetration—allows the growth of root into it.

Mechanical resistance was tested by flushing water throughout a container filled with SAP and sand soil, Initial, final weights and dimensions were recorded. A pass mark was accepted for SAP that maintains a single element and didn't wash away or split into several parts. Three groups of SAP were synthesized and tested:

SAPs
Group	Poly sugar	Semi synthetic	Fully synthetic
Type	Alginate	CMC-g-poly (acrylic acid)/Celite	Acrylic
		composite system Carboxymethyl	Acid/Acryl
		cellulose grafted polyacrylics acid	Amide
		with Celite as a filler.
		k-Carrageenan poly(acrylic
		acid)SAP

Each type of SAP was formulated with variable mixture of poly sugars, crosslinked agents, filler and additive. Moreover, samples were oven dried and immersed in distilled water in order to calculate the equilibrium swelling (ES) according to the following equation:

$\mathrm{ES}=\frac{\mathrm{weight}\mathrm{of}\mathrm{swollen}\mathrm{gel}-\mathrm{weight}\mathrm{of}\mathrm{Dried}\mathrm{gel}}{\mathrm{weight}\mathrm{of}\mathrm{Dried}\mathrm{gel}}$

Table 1 summarizes the findings of the mechanical resistance tests:

		Bis-
SAP-Group	SAP-type	AAm/AA	% PS/AA	NaOH	ES
Semi-	CMC	0.75-1.25	50-75	15-25	73-467
synthetic	k-Carrageenan	1.6-2.5	33-66	—	25-72
Poly sugar	Alginate-2%	—	100	—	38
Fully	Acrylic	—	0	—	180
synthetic	(AA/AM)
“Bis-AAm/AA” means (Acrylic acid crosslinked with Bis acrylamide,”
“% PS/AA, semi-synthetic Polysugar - acrylic acid hydrogel” and
“ES” means “equilibrium swelling.”
“Alginate-2%.” means 2% in water when hydrated.

1) Poly Sugar:

• • 16 gr of sodium alginate was dissolved in 800 ml distilled water at 50° C. using mechanical stirrer (1000 RPM). Then 20 gr from the alginate solution was added in to 50 ml beaker, then 10 gr of 0.1 M solution of CaCl₂, was added in to the beaker (CaCl₂ served as the cross-linking agent). The beads were left in the solution for 12 hr.

2) CMC-g-Poly (Acrylic Acid)/Celite

• • Various amounts of CMC (Carboxymethyl cellulose sodium Salt) (0.5-2 g) were dissolved in 25 ml distilled water and were added to a 100 ml beaker with magnetic stirrer. The beaker was immersed in a temperature controlled water bath preset at 80° C. After complete dissolution of CMC, various amounts of Celite powder (0.3-0.6 g in 5 ml water) were added (if any) to the solution and allowed to stir for 10 min. Then, certain amounts of AA (Acrylic Acid) (2-3 ml) and MBA (N—N methylene bis acrylamide) (0.025-0.1 g in 5 ml water) were added to the reaction mixture and allowed to stir for 5 min. Then the initiator solution (0.07 g APS (Ammonium persulfate) in 5 ml water) was added to the mixture, the mixture was placed immersed in a temperature controlled water bath preset at 85° C. for 40 minutes to complete polymerization. To neutralize (0-100%) acrylic groups, appropriate amount of NaOH (0-1 gr in 5 ml water) was added. The obtained gel was poured to excess nonsolvent ethanol (80 ml) and remained for 1 h.
    3) k-Carrageenan (kC) Cross-Linked-Poly(Acrylic Acid)

0.5-1 gr of kC (k-Carrageenan) was dissolved in 25 mL of distilled water, which was under vigorous stirring in a 100 ml beaker with a magnetic stirrer. The flask was immersed in a temperature controlled water bath at 80° C. After complete dissolution of kC to form a homogeneous solution, certain amounts of AA (Acrylic Acid), and MBA (N—N methylene his acrylamide) simultaneously added to the reaction mixture. Afterward, the solution was stirred and purged with nitrogen for 2 min to remove the dissolved oxygen. Then, a definite amount of APS (Ammonium persulfate) solution was added dropwise to the reaction flask under continuous stirring to generate free radicals. The reaction maintained at this temperature for 1 h to complete polymerization.

4) Fully Synthetic System (a Sample for AAm):

AAm (Acrylamide) (10 g) was mix with 25 ml distilled water at room temperature in a 50 ml beaker equipped with magnetic stirrer. Then MBA (N—N methylene his acrylamide) (0.008 gr) was added into the mixture and allowed to stir for 10 min. Then an initiator solution was added (0.07 g SPS (Sodium persulfate)). The mixture was placed into 5 ml template (4 gr solution each) and placed in a convention furnace (85° C.) for 20 min. The product was washed overnight with ethanol (80 ml) to obtain the polymerized shell.

Starch Systems—Sample for Non-Growing Media

1) Modified Starch Cross-Linked Poly(Acrylic Acid)

1-2.5 gr of Corn starch dissolved in deionized 20 ml water in 100 ml beaker at room temperature. The combination was mixed until a uniform mixture was formed. 2-3 gr AA (Acrylic acid) was added to the cooled mixture and the resulting mixture was stirred for five minutes. Next, 1-3 gr AAm (acrylamide) was added to the mixture, and the resulting mixture was stirred for five minutes. Then 0.005-0.01 gr of MBA (N—N methylene bis acrylamide) dissolved in 5 ml of deionized water was added to the mixture, and the resulting mixture was stirred for five minutes. Lastly, 0.005 gr of APS (ammonium persulfate) dissolved in 0.5 ml of deionized water; was added to the mixture and the resulting mixture was stirred while being heated to 80° C. The mixture was held at that temperature and stirred for approximately 15 minutes. Because the resulting viscous mass was acidic, the mixture was neutralized by titration with 45% potassium hydroxide (KOH) at room temperature. Titration continued until a pH of 7.0 was reached, which required addition of between about 0.2-16 g 45% KOH.

2) Similar Process to the CMC-AA System.

(Exchanging CMC with Corn-Starch):

• • 1 gr of corn Starch was dissolved in 25 ml distilled water and were added to a 100 ml beaker with magnetic stirrer. The beaker was immersed in a temperature controlled water bath preset at 80° C. Then 2 ml of AA (Acrylic Acid) and MBA (N—N methylene bis acrylamide) (0.015 g in 5 ml water) were added to the reaction mixture and allowed to stir for 5 min. Then the initiator solution (0.07 g APS (Ammonium persulfate) in 5 ml water) was added to the mixture, the mixture was placed immersed in a temperature controlled water bath preset at 85° C. for 40 minutes to complete polymerization. NaOH (0.5 gr in 5 ml water) was added in order to neutralize acrylic groups. The obtained gel was poured to excess nonsolvent ethanol (80 ml) and remained for 1 h.

Swelling cycles of selected formulations in water and two types of soil were tested. The ability of the SAPs to absorb water in relatively short time is an important physical property that allows maintaining its functionality in the soil throughout its life cycle. The following graphs present the swelling behavior of the different SAPs upon hydration-dehydration cycles in water. The ES of the investigated SAPs stay constant during three cycles, meaning good mechanical properties.

The water content of several SAPs in sandy silica soil was measured following watering over a time period that is a typical watering cycle of crops and plants. The various SAPs gain water from the soil in the first 24 hours following by a mild decrease/increase over the next 125 hours. When SAPs were introduced to air dry loess soil, initially it went under rapid de hydration, yet watering the soil reverse the process and water were absorbed from the soil the soil recovery percentage were 99 and 50. The results indicate that all groups of SAPs can maintain their moisture in the sandy soil over a watering cycle and that CMC base SAPs can fully recovery from extreme dry condition in soil.

Oxygen permeability of the SAPs was studied by measuring dissolved oxygen in water that was exposed to oxygen saturated water across a SAP, Altering dissolved oxygen level was done by bubbling nitrogen or oxygen gases into the water reservoir located opposite the sensor, SAPs made from Alginate and CMC showed an order magnitude more oxygen permeability than SAP of k-carrageenan (FIG. 4).

Dissolved Oxygen Test:

Oxygen electrode place into a pre-swelled hydrogel in a 100 ml beaker. The dissolved oxygen inside the hydrogel was measured during N₂ bubbling or O₂ bubbling (˜0.5 liter per minute) as a function of time.

The O₂ measurements made by Lutron WA2017SD Analyzer with dissolved oxygen probe 0-20 mg/L, 0-50° C. The Dissolved Oxygen System is shown in FIG. 13.

Root penetration was evaluated visually from a series of experiments, where various crops grew in pots filled with organic soil surrounded an artificial environment. Table 2 summarizes the observations presented in FIG. 10:

			Roots	Roots
		Roots on the	penetrated	developed
		surface of	into	in the
		artificial	the artificial	artificial
SAPs	Crop	environment	environment	environment
Poly Sugar-	Pea	−	+	+
Alginate
Semi synthetic-	Corn, Pea,	+	+	−
CMC
Semi synthetic-	Pea	+	+	−
k-Carrageenan
Fully synthetic	Corn	+	+	−

Example 2

The Internal zone

Three mechanisms were developed and evaluated to address the criteria of i) release rate of agrochemicals from the internal zone over a growing season, and ii) that no input residuals remain at the end of a predetermined action period. All the three, are based on integrating the input into a very dense polymer as the basic mechanism to slow down diffusion, in conjunction to a secondary mechanism that will additionally decrease the diffusion rate:

• • 1) Highly Cross Linked Polymer with silicon coating (xLP-Si);
  • 2) Highly Cross linked Poly Acrylic/poly sugar with filler (xLP-F); and
  • 3) Hybrid system (SiCLP-).

The first mechanism is based on precipitation of silica, originated from silica water, on the surface of the polymer (FIG. 4).

The second mechanism is based on filler, made from bentonite, integrated into the polymer and decreases sharply its diffusion properties (FIG. 6).

The third mechanism is to mix the silica with the acrylic while synthesizing the polymer in order to alter its diffusion coefficient (FIG. 7).

The reduction in diffusion properties by each mechanism was experimentally tested. The internal zone was located in a free water reservoir where the concentration of a certain input (Nitrogen or Phosphorus) was measured over time.

The release of nitrate from cornstarch internal zone with (blue) and without (red) silica coating is presented in FIG. 7. A reduction of diffused nitrate was measured in the first 24 hours.

Alternatively, the mixed silica mechanism yielded release of nitrate and phosphorus in the scale of weeks, as well.

Example 3

Stability, Dimensions, and Mechanical Resistance of Hydrogels Applied to a Field Plot

Objective

The objective of this example was to study the sustainability in soil, hydrated dimensions and mechanical resistance of different types and sizes of hydrogel within a field plot. Furthermore, root penetration into these types of hydrogels was studied.

Hydrogels

The types and sizes of hydrogels are described in Table 3 below:

		Small	Medium	Large
		(hydrated	(hydrated size	(hydrated size
No.	Chemical composition	size of 2-3 cm)	of 4-5 cm)	of 7-8 cm)	Geometry
1	Fully synthetic		+		Box
2	Semisynthetic CMC 6%	+	+	+	Cylinder/Box/Cylinder
	AAm
3	Semisynthetic CMC 6% AA		+		Box
4	Semisynthetic CMC 25%		+		Box
	AA
5	Semisynthetic CMC 50%	+	+	+	Cylinder/Box/Cylinder
	AA
6	Polysugars Alginate		+		Cylinder

The fully synthetic hydrogel had the composition of the fully synthetic hydrogel described in Example 1.

The semisynthetic CMC 6% AAm hydrogel comprises 6% CMC relative to the acrylic acid monomers (Acrylamide-acrylic) and was made by the following process. 0.25 g AA was mixed with 4.5 ml distilled water at room temperature in a 50 ml beaker equipped with a magnetic stirrer. Then 0.1 g NaOH, 0.01 g MBA, 0.75 g AAm and 1.5 gr CMC solution (3.8% w/w) were added into the mixture and allowed to stir for 10 minutes. Then an initiator solution comprising 0.1 g SPS was added. The mixture was placed into a 5 ml template (4 g solution for each shell) and placed in a convention furnace at 85° C. for 20 minutes. The product was washed overnight with 80 ml ethanol to obtain the polymerized shell.

The semisynthetic CMC 6% AA hydrogel comprises 6% CMC relative to acrylic acid and was made by the following process. 1 g AA was mixed with 4.5 ml distilled water at room temperature in a 50 ml beaker equipped with magnetic stirrer. Then 0.4 g NaOH, 0.01 g MBA and 1.5 g CMC solution (3.8% w/w) were added to the reaction mixture and allowed to stir for 10 minutes. Then 0.1 g of SPS was added. The mixture was added into a 5 ml template (4 g solution for each shell), and the template was placed in a convention furnace at 85° C. for 20 minutes. The product was washed overnight with 80 ml ethanol to obtain the polymerized shell.

The semisynthetic CMC 25% AA hydrogel comprises 25% CMC relative to acrylic acid and was made by the following process. 2 g AA was mixed with 12.5 g CMC solution (3.8% w/w) at room temperature in a 50 ml beaker equipped with magnetic stirrer. Then 0.01 g MBA was added into the mixture and allowed to stir for 10 minutes. Then an initiator solution comprising 0.1 g SPS was added. The mixture was placed into 5 ml template (4 gr solution for each shell), and the template was placed in a convention furnace at 85° C. for 20 min. Then NaOH (0.728 molar ratio or 0.8 gr in 50 ml water) was added to the polymerization product. The product was then washed overnight with 80 ml ethanol to obtain the polymerized shell.

The semisynthetic CMC 50% AA hydrogel comprises 50% CMC relative to acrylic acid and was made by the following process. 1.5 g CMC were dissolved in 35 ml distilled water and added to a 100 ml beaker with magnetic stirrer. The beaker was immersed in a temperature controlled water bath preset at 85° C. After complete dissolution of CMC, the beaker was placed on a magnetic stirrer at room temperature with N₂ bubbling at a flow rate of ˜0.5 LPM. Then 3 g AA and 0.03 g MBA were added to the reaction mixture and allowed to stir for 20 minutes and the temperature was allowed to decrease to 35° C. Then the 0.03 g of the initiator SPS in 1 ml water was added. The mixture was placed into 5 ml template (4 g solution for each shell) and placed in furnace at 85° C. for 20 minutes. Then NaOH (0.728 molar ratio or 0.8 gr in 50 ml water) was added to the polymerization product. The product was then washed overnight with 80 ml ethanol to obtain the polymerized shell.

The polysugars alginate hydrogel had the composition of the polysugar hydrogel described in Example 1.

Experimental Setup

The experiment took place at the Southern Arava R&D station. A 125 square meters field plot, divided to 4 beds×15 m long was served to test 3 application methods, six types and three sizes of hydrogels. Root penetration was studied in plot D.

The experimental setup is shown in FIG. 14.

The three application conditions for plots A-C were:

i) Uniform application in loose soil—to mimic conventional beds for vegetable crops;
ii) Uniform application in compacted soil—to mimic conventional beds for vegetable crops, with compaction; and
iii) Application in a furrow—to mimic a furrow in field row crops.

A one square meter or one linear meter sub plots (50 cm apart) were used to apply 27 units of each hydrogel (plots A-C). The units were uniformly distributed on the soil surface and incorporated into the upper 15 cm of the soil profile. Similarly, a 20 cm deep furrow was dug and 27 units were distributed along one meter. Water was applied through a solid sprinkler set without fertilizer (1 m³=8 mm).

The roots penetration plot (plot D) consisted of a 15 m long bed, where 25 hydrogels from each type were applied along a 1 m furrow of 20 cm deep. Maize was sown above the at the same day and was irrigated with a solid set of sprinklers without fertilizes, that was switched after germination to a drip line (25 cm spacing, 2 l/h) with Idit liquid fertilizer (100 mg/l N). Irrigation was shut off on day 31 and was opened again one day before soil excavation. Visual dimensional measurements and qualitative information on root penetration were collected on day 50.

Measurements included individual weight, dimension and tension of 3 units. Timing of water application to plots A-C and measurements are shown in Table 4 below:

Day	Irrigation (mm)	Measurements
0	Application
1	160
2		1st
5	40
6		2nd
8	40
12	40	3rd (before
		irrigation)
16		4th
29		5th

Climate during the experiment was clear sky with no rainfall. Maximum and minimum soil temperatures at 5 cm depth during the experiment period are presented in FIG. 15. The hydrogels were exposed to temperatures which ranged between 10° C. at night to 40° C. around midday.

Results for Plots A-C

Changes in weight for each hydrogel type and size versus time are shown in FIG. 16. The variable soil moisture was derived by the irrigation events (vertical bars). During the wetting phase, comprising of four consecutive irrigations (day-12), most of the hydrogels gained weight by absorbing soil water. The poly sugar Alginate was the only type to lose weight throughout the experiment, although soil moisture fluctuated between very wet to mild dry soil. While medium and large hydrogels multiplied their own weight (equal to the amount of absorbed soil water) by 5-11 times, the small hydrogel grew by 18 times. During the 16 days drying phase, hydrogels lost weight by 2-4 times (of the original weight) to the drying soil. No correlation between CMC percentage and water absorbance was found. This may imply that local conditions are more dominant than chemical composition.

The final surface area derived from the volume and the geometry of the hydrogels is shown in FIG. 17. Initial areas ranged between 25-30 cm² for medium size, 35 cm² for large size and 10 cm² for small size. Most medium hydrogels experienced a minor increase, up to 35 cm², while Alginate decreased sharply and Semisynthetic CMC 50% AA (no. 5) increased dramatically to 60 cm². The two large sizes increased to over 50 cm². Surface area of hydrogel units versus time is shown in FIG. 18.

The ratio between surface areas to volume was constant to most hydrogels at the value of 2.5-3. The poly sugar Alginate and both small size hydrogels had high ratio due to their relatively small dimensions. Surface area to volume ratios for the hydrogels are shown in FIG. 19.

The distance between a chemical (positioned inside the hydrogel) and the adjacent soil determines the diffusion rates towards the soil. The minimal distance stands for the smallest edge of the hydrogel geometry. Moreover, the same value describes the potential zone for root growth. The initial minimal distance was in the range of 1-2 cm and final values increased to 1.5-2.5 cm. This entails that a chemical will need to diffuse 1-2 cm prior to reaching the soil. The poly sugar Alginate shrunk over time, reaching 0.5 cm in width. The small size hydrogel was difficult to follow, yet it stretched to 0.75 cm. Final minimal distances of the hydrogels are shown in FIG. 20. FIG. 21 shows the minimal distance of hydrogel units versus time.

Stiffness is an important parameter related to the potential of roots to penetrate the media and the potential of water to be absorbed. Measurements of stiffness were achieved by using a penetrometer gauge and a metal disc. The values shown in FIGS. 22 and 23 are in relative scale, representing the force that was required to push the disc on the surface of the hydrogel. No differences between medium and large sizes were found. The poly sugar Alginate was consistently very stiff throughout the experiments, contrary to the fully synthetic, which was relatively flexible. A negative trend between CMC content and level of stiffness was observed.

A photo of each hydrogel at the end of the experiment is shown in FIG. 24. The Fully synthetic, Semisynthetic CMC 6% AAm, Semisynthetic CMC 25% AA maintained the original box shape. Similarly, Semisynthetic CMC 6% AAm-Large, Semisynthetic CMC 50% AA-Large and Semisynthetic CMC 6% AAm-Small maintained the cylindrical geometry. Several hydrogels, made from Semisynthetic CMC 6% AA, disintegrated into small particles. Semisynthetic CMC 50% AA lost its original box geometry and turned into an undefined geometry. The poly sugars Alginate turned into a flat disc.

Results for Plot D

Hydrogels nos. 6, 9 and 10 could not be found in the root zone at the end of the experiment. Photos of each hydrogel type at the end of the experiment are shown in FIG. 25. The left photo shows the hydrogels in-situ and the right shows a few samples where roots penetrated through it. Fully synthetic, Semisynthetic CMC 6% AAm, and Semisynthetic CMC 25% AA maintained the original box shape. Similarly, Semisynthetic CMC 6% AAm-Large and Semisynthetic CMC 50% AA-Large maintained their cylindrical geometry. Several hydrogels, made from Semisynthetic CMC 6% AA, disintegrated into small particles. Semisynthetic CMC 50% AA lost its original box geometry and turned into an undefined geometry. All types of hydrogel experienced shrinkage relative to its maximum volume measured in the bare soil plots. Roots penetrated into all types of hydrogels. While course roots penetrated into the Fully synthetic, Semisynthetic CMC 25% AA and Semisynthetic CMC 50% AA hydrogels, only fine roots were found in the Semisynthetic CMC 6% AAm, Semisynthetic CMC 6% AA and Semisynthetic CMC 6% AAm-Large.

Summary

Six types and three sizes of hydrogels were tested in a field plot during wetting and drying periods. Most of them were in accordance with soil moisture, absorbing water (up to 10 times their initial weight) in the first period and releasing water in the second one. Final surface area was 30-50 cm². The minimal dimension of the medium and large hydrogels was 1.5-2.5 cm, allowing sufficient volume for root penetration. Small hydrogels expanded to less than 1 cm, which would constrain the amount of chemicals which could be encapsulated within the hydrogel. Stiffness was evaluated and a major difference was found between hydrogel types. While most types maintained their original 3D geometry, a few disintegrated or deformed.

Six types and three sizes of hydrogels were evaluated in a field plot for root penetration. Most types maintained their original 3D geometry, yet a few disintegrated, deformed or flushed away. Roots penetrated into all hydrogels, but a few types had only fine roots while others had fine and course roots. The amount of root penetration and development observed in the different size hydrogels suggests that a minimum volume of hydrogel is required for root penetration and development.

Example 4

Performance of Hydrogels Loaded with Fertilizer in Different Soil Types

Example 3 demonstrated the ability of hydrogels to sustain in the field soil under wet and drying cycles. Moreover, roots penetrated into the hydrogels suggesting the potential use to deliver chemicals directly to roots. Current practices to deliver fertilizers to the plant roots mostly involve application of fertilizers to the soil, a highly variable media (physically, chemically and biologically). Such practices yield low efficiency of fertilizer uptake.

Objective

The primary objective was to study the effectiveness of hydrogels loaded with fertilizer (fertilizer units) to supply plant uptake requirements throughout the growing season. The secondary objective was to test the development of fine roots, dominant in mineral uptake, within the hydrogel.

Fertilizer Units

The composition of the fertilizer units of Example 4 was as shown in Table 5:

% w/w
Fertilizer units - composition
Osmocote ® Start 6 Weeks       14%
Polymer                        86%
Polymer composition
Acrylic Acid                   3%
Acryl-Amide                    8%
CarboxyMethyl Cellulose sodium <1%
salt
Sodium Persulfate              1%
N—N methylene bis acrylamide   <1%
Water                          74%

Experimental Setup

The experiment took place at the Southern Arava R&D station. Twenty three rotating weighing lysimeters (FIG. 26) served to test the fertilizer units versus fertigation (Fert.) and slow release fertilizer (SR, Osmocote® Start 6 Weeks, Everris). The system allowed accurate monitoring of quantity and quality of irrigation and drainage water and plant water uptake. Fertilizer units, containing 0.625 g of the slow release fertilizer (N:P:K ratio by weight was 12:4.8:14.1+micronutrients), were distributed evenly at three depths: 30, 20 and 10 cm (FIG. 27). Total weight of each unit during application was 6-7 g.

Sunflowers were used as a model plant. Two sunflowers were grown in each lysimeter. The lysimeters were irrigated daily (clay soil-twice a week) at an average rate of 200% of measured actual Evapotranspiration (ET). The high leaching factor was designed to minimize drought and salinity effects.

The experiment was divided into three stages:

Stage 1: Comparing the application of slow released fertilizer to fertilizer units.

Stage 2: Separating between water and fertilizer effect on plant development.

Stage 3: Evaluating the fertilizer unit performance in different soil types.

The experimental setup is shown in Table 6:

			Fertilizing
		Fertilizing	rate vs. plant	Lysimeters
	soil	technology	requirement	nos.	Note
Stage	Dune	fertilizer unit	100% (Full)	12, 13, 14	90 fertilizer
1	sand				units
		fertilizer unit	50% (Half)	15, 16, 17	45 fertilizer
					units
		SR	100% (Full)	4, 5, 6	None
Stage	Dune	fertilizer unit	100% (Full)	9, 10	45 fertilizer
2	sand				units
		Empty unit +	100% (Full)	7, 8	45 Empty
		Fert.			units
Stage	Grow-	fertilizer unit	100% (Full)	1	45 fertilizer
3	ing				unit
	Media	SR	100% (Full)	21	45 fertilizer
					units
	Clay	fertilizer unit	100% (Full)	18	45 fertilizer
					units
		SR	100% (Full)	3	45 fertilizer
					units

Stage 1

The sunflowers were sown on day 0 and harvested on day 33. Dune sand was selected due to its inerratic properties, minimizing adsorption to clay minerals and precipitation due to low bicarbonate content. Application dose of N, P and K per plant for each treatment is depicted in FIG. 28. Plant height, no. of leaves, Soil Plant Analysis Development (SPAD) values and NPK in drainage water were recorded at points during the growing season. Final yield quantification included dry biomass and NPK content of the whole plant. Following harvest, the fertilizer units were excavated and NPK content was quantified.

Stage 2

The sunflowers were sown on day 0 and harvested on day 36. Application dose of N, P and K per plant for each treatment was half of the values depicted in FIG. 28. Plant height, no. of leaves, SPAD values were recorded at points during the growing season. Final yield was evaluated as wet biomass.

Results

Stage 1

Plant height, number of leaves and its N content, represented by SPAD values, throughout the growing season are presented in FIG. 29.

Differences in height and leaves between the fertilizer units and SR started from the beginning of the growing season and continued till the end (see FIG. 35). SPAD values were higher during the main nutrient application period (DAP 20-45). The lower SPAD values measured at the end of the growing season for fertilizer unit treatment were attributed to earlier maturity, where nutrients are being transferred from the leaves to the seeds.

Plant dry matter, absolute NPK uptake amount and its efficiency are presented in FIG. 30. The fertilizer units yielded larger plants and NPK uptake versus the Slow Release fertilizer. Within the fertilizer unit treatment, the full fertilization achieved higher plants and uptake, yet the efficiency was equal. The greatest fertilizer use efficiency of the fertilizer unit demonstrates the advantage of the new technology over current best practices.

Relative residuals of NPK in the fertilizer units are depicted in FIG. 31. The lower values, less than 6%, indicate that most of the fertilizer was taken up by the plant or diffused to the soil.

Stage 2

The dune sand, used in stage 1, has a low water holding capacity and high hydraulic conductivity, meaning that daily irrigation may not optimize day time plant water availability. The hydrogel's shell has the potential to improve water availability by absorbing water during irrigation and release it later at dry periods. Therefore, it was possible that the significant differences found in stage 1 could relate to two factors, namely fertilizers and water availability. Therefore, a comparison between fertilizer units and empty fertilizer units installed in the root zone & fertigation (Empty units+Fert.) was conducted in stage 2.

Plant height, no. of leaves, SPAD value along the growing season and wet biomass from each treatment are presented in FIG. 32. Plants exposed to fertilizer units were advantageous over empty units+Fert at all parameters (see FIG. 35), suggesting that water availability plays a minor role relative to fertilizer supply under the experimental conditions. Plants which were fertilized by fertilizer units exhibited faster growth and enhanced biomass production.

Stage 3

The main drawbacks the invention overcomes in soils are:

• • Diminishing leaching, adsorption and precipitation of ions.
  • Maintaining high diffusion rate at variable moisture conditions.
  • Minimizing root growth resistance.
  • Allowing continuous biological activity.
  • Improving water holding capacity.

These drawbacks can be overcome by replacing the soil with growing media, which is considered to provide the best conditions for plant growth. This hypothesis was tested by comparing the fertilizer units, SR and Fert. fertilization methods. The performance of fertilizer units in heavy clayey soil was tested at the 3rd stage.

Plant height, no. of leaves, SPAD value along the growing season and wet biomass for each treatment are presented in FIG. 33. No significant differences were measured between treatments (see FIG. 35), suggesting that growing media generates similar properties as fertilizer units.

Plant height, no. of leaves, SPAD value along the growing season and wet biomass for each treatment are presented in FIG. 34. Visual results of Example 4 are shown in FIG. 35. Fertilizer units improved plant growth compared to SR (see FIG. 35), demonstrating that fertilizer units are advantageous in various soil types.

Summary

The study demonstrated the ability of the fertilizer units to deliver nutrients to plants throughout the growing season in various soils. Moreover, fertilizer units enhanced plant growth and final yield. The higher fertilizer use efficiency over current practice was due to various reasons:

• • Extensive growth of active roots adjacent to the fertilizer source (See FIG. 35).
  • Limited leaching from the fertilizer unit due to lack of mass flow across it.
  • Maintaining high diffusion rates within the fertilizer unit in drying soil due to steady high moisture levels (unlike soil).

Since the release rate of the fertilizer in this experiment was temperature dependent, the extreme high temperature which existed in the soil (average max. soil temp of 45.3° C.) enhanced the diffusion rate and therefore the absolute efficiency values were relatively low (FIG. 30).

Roots did not penetrate empty units, probably due to a lack of fertilizer within the hydrogel and sufficient moisture for plant uptake.

The uptake efficiency shown in FIG. 30 represents the ratio between the amount of fertilizer applied to the amount taken up by the plant. The higher uptake efficiency values observed for the fertilizer units compared to traditional SR fertilizer (FIG. 30) suggests that less leaching of fertilizer towards groundwater occurs when fertilizer is applied using fertilizer units.

Example 5

Comparison of Fertilizer Units to Slow Released Fertilizer and Fertigation in Sunflower and Cabbage

Objective

The objective was to study the effectiveness of hydrogel loaded with SR fertilizer (fertilizer units) as a method of supplying plant nutritional requirements throughout the growing season under field conditions.

Experimental Setup

The experiment took place in a field plot located in the Western Galilee in Israel (N 33, E55). The site is characterized with heavy alluvial soil, rich in clay minerals, which induces high cation exchange capacity (≈50 meq/100 g), high pH (≈8) and intermediate salinity salinity (EC of saturated paste-0.5 dS/m). Dry weather conditions with mostly clear skies (average direct radiation—670 W/m²) were prevalent throughout the experiment. Maximum and minimum air and soil temperatures, midday relative humidity and day time during the trial are presented in Table 7:

	Max.	Min.
	Air temp. (° C.)	34.2-24.5	34.2-24.5
	Soil temp. (° C.)	32.1-11.4
	Midday Relative humidity (%)	71-12
	Day time (hh:mm)	13:41-10:29

A 150 square meter plot was divided into subplots based on randomized block design (FIG. 36). To ensure initial low levels of soil nitrogen (N), millet was grown on the field plot without complementary fertilization for 30 days prior to trial initiation. The fertilizer units were compared to fertigation (Fert.—Urea based) and to slow released fertilizer application (SR, Osmocote® Start 6 Weeks, Everris). Equal irrigation and N quantities were applied to all treatments. Nitrogen application rates were based on literature values, where cabbage was reported to utilize 3.6 g of N per plant and sunflower was reported to utilize 3 g of N per plant. Plants were irrigated twice a week based on ET measurements and literature values for plant cover coefficient. Irrigation of sunflowers was ceased two weeks prior harvesting. The crops were planted on day 0 with planting densities of 40,000 plants per hectare. The cabbage was harvested on day 70 and sunflower was harvested on day 89.

The monitoring plan (Table 8) included plant development parameters throughout the growing season and final yield analysis. Data was collected from pre-marked plants, six plants in the middle row (cabbage) and 6-10 plants which exhibited similar development stage after two weeks (sunflower).

TABLE 8
		Developing	Yield
Crop	Pre-plant	parameters	analysis	Post-harvest
Cabbage	Soil NPK	Plant diameter	Wet weight of	Soil N
	content*		head and leaves	content*
		No. of leaves	Dry weight of
			head and leaves
		Head diameter	N content in head
			and leaves***
Sunflower		NPK content in
		leaves
		Plant height	Wet weight of
			flower and leaves
		No. of leaves	Dry weight of
			flower and leaves
		Flower	N content in
		diameter	flower***
		SPAD values**	Weight of dry
			seeds
		NPK content in
		leaves
*SM3500K and SM4500P-NO;
** Chlorophyll content optical sensor- Minolta, SPAD 502B;
***kjeldahl-colorimetric

Fertilizer Application

Fertilizer units, weighing 6-7 g and containing 1 g of SR (N:P:K ratio by weight was 12:4.8:14.1+micronutrients), were evenly distributed at two depths: 25 and 15 cm. Total fertilizer unit application was 80 units (80 grams) per meter length for the cabbage and 100 for sunflower. SR was distributed evenly at similar rates and depth. The cabbage fertigation treatment was set to weekly applications of Urea-N with irrigation water, following a predetermined plan base on literature values of plant N requirement. The sunflower fertigation treatment was executed similarly, with the total plant N requirement applied during the first two weeks.

Results

Averages and standard deviations (fertilizer units only) of sunflower height, cabbage leaf diameter, number of leaves and SPAD values (sunflower only) throughout the growing season are presented in FIG. 37. Differences were measured between the fertilizer units, SR and fertigation treatments in height, diameter, leaf number and SPAD (see Table 9) at variable stages and maintained until the end. The improved parameters suggested enhanced growth conditions under fertilizer unit application for both crops.

TABLE 9
Statistical groups (Anova)
	Fertilizing method
Crop	Parameter	fertilizer unit	SR	Fert.	P
Sunflower	Height	A	A	A	0.562
	Leaves	A	B	B	<0.001
	SPAD	A	B	B	<0.001
	Grains yield	A	A	A	0.537
	N uptake	A	A	A	0.696
Cabbage	Leaves	A	B	B	0.005
	diameter
	Leaves	A	B	B	0.005
	Yield	A	B	AB	0.242
	Biomass	A	AB	B	0.005
	N uptake	A	A	B	0.004

Leaf nutrient content was measured at 55 days after planting, where both crops finalized their vegetative growth. No significant differences were found between treatments. Plants under fertilizer unit application did not exhibit nutritional deficiencies relative to traditional fertilizer application methods at this stage of growth (FIG. 38).

The development of cabbage yields (FIG. 39B) was evaluated from the linear ratio between head diameter and its weight (FIG. 39A). The advantage of the fertilizer unit application was most noticeable 60-70 days after planting.

Final yield analysis of cabbage biomass and N uptake for fertilizer unit versus conventional fertilizer application methods is shown in FIG. 40, Significant differences were measured between the fertilizer unit and fertigation treatments, implying that nutrients are less available for plant uptake using conventional fertilizing methods.

The final yield analysis of sunflower showed similar grain yield and N uptake by plants fertilized by the fertilizer unit application method relative to conventional fertilizer application methods (FIG. 41). Although no significant difference was measured, plants exposed to fertilizer units uptake more N than plants exposed to conventional fertilizing methods.

Residuals of NPK in 10 fertilizer units from each plot are depicted in FIG. 42. Nitrogen residuals were less than 2%, P less than 8% and K Less than 2.5%. These values indicate that most of the fertilizer was taken up by the plants or diffused into the soil.

Residuals of N in the root zone (upper 30 cm of soil profile) of each crop are presented in FIG. 43. Nitrogen accumulation in the root zone was tenfold higher in the sunflower plots and 4 times higher in the cabbage plots.

Nitrogen mass balance was calculated in the root zones of cabbage and sunflower (FIG. 44). Fertilizer units exhibited higher N uptake efficiency over conventional fertilizing techniques, suggesting enhanced availability of fertilizers to plant uptake within the fertilizer units.

Summary

This study demonstrated the ability of the fertilizer units to deliver nutrients to plants throughout the growing season under normal field conditions. Moreover, fertilizer units enhanced plant growth (sunflower and cabbage) and increased the final yield (especially cabbage) compared to current practice. The higher N use efficiency over current practices is attributed to the following reasons:

• • 1. Extensive growth of active roots adjacent to the fertilizer source (determined visually).
  • 2. Limited leaching from the fertilizer units due to lack of water flow across it.
  • 3. Maintaining high diffusion-dispersion rates within the fertilizer units in drying soil due to steady high moisture levels over time (unlike soil).

Example 6

Pilot Scale Production of Fertilizer Units Based on AA-AAm-CMC Hydrogels with Onsmocote® 6 Weeks Cores

This Example describes the production of fertilizer units useful in the methods of the invention.

Materials

Acrylic Acid (AA) (Sigma Aldrich catalog #147230)

Acrylamide (AAm) (Acros catalog #164830025)

N—N methylene his acrylamide (MBA) (Sigma Aldrich catalog #146072)

Carboxymethylcellulose Sodium salt MW=90K (CMC) (Sigma Aldrich catalog #419273)

Sodium persulfate (SPS) (Sigma Aldrich catalog #216232)

Deionized water (DIW)

Osmocote® start 11-11-17+2MgO+TE, Everris International B.V. (Scott).

Methods

8 kg of a 3.8% w/w CMC stock solution is made by slowly adding 304 g of CMC powder to 7,696 g of 90° C. DIW followed by stirring for 12 hours at 50° C. Additional DIW is added to replace any water which evaporates during the 12 hours of stirring.

12 kg of a pre-monomer solution is made by first making an AA solution by slowly adding 336 g of AA to 5,990 g of DIW, then adding 384 g of KOH 50% (w/w) solution, and mixing the solution for 15 minutes at 36° C. and pH 4.7. 1,009 g of AAm and 10.09 g MBA is then added to the AA solution and mixed for 15 minutes. 4,238 g of a 3.8% CMC stock solution is then added to the solution and the solution is mixed for 30 minutes to provide the pre-monomer solution.

2 L of a monomer solution with initiator is made by adding 4.5 g of SPS into 2 kg of the pre-monomer solution and mixed for 20 minutes.

The fertilizer units are made in two polymerization steps. In the first step, a bowl-like hydrogel structure is made by adding 4 ml of the monomer solution to a beads pattern using a multi-tip dosing devise. The beads pattern is then covered with a cones matrix and placed in a furnace at 85° C. for 60 minutes, thereby forming the bowl-like hydrogel structure. 1 g of Osmocote® beads are then added to the bowl-like structures. In the second polymerization step, an additional 3.5 ml of monomer solution is added to the beads pattern using the multi-tip dosing device. The beads pattern is then placed in a furnace at 85° C. for 60 minutes, thereby forming the complete fertilizer unit.

The fertilizer units are removed from the beads pattern and washed with ethanol for 10 minutes (50 beads in 1 L ethanol). The fertilizer units are then washed with water for 10 minutes (50 beads in 1 L ethanol). The fertilizer units are then dried at room temperature to a final weight of 3.5-4 g. Beads produced using the above process are shown in FIG. 46.

A bead produced using the above process swells to 90-100 g when placed in 200 ml DIW for 24 hours and swells to 35-50 g when placed in 200 ml saline water (0.45% NaCl by weight) for 24 hours. FIG. 47 shows a fully swelled fertilizer unit produced by the above process compared to a fully dried fertilizer unit.

Example 7

Performance of Fertilizer Units Under Low Ambient Temperature Growth Conditions

Objective

The objective was to determine the ability of fertilizer units to improve plant survival under low ambient temperatures.

Experimental Setup

Fertilizer units similar to those described in Example 6 were added at depths of 10 and 20 cm to 80 L pots filled with sand and clay soils. Cucumber plants were grown in the pots for 63 days within a net house. Control plants were grown under same conditions with fertilizers supplied as liquid with the irrigation water rather than as fertilizer units.

Results

Enhanced heat capacity of the root zone, due to the fertilizer unit application, was demonstrated to improve plant survival under low ambient conditions as shown in Table 10.

TABLE 10
			Heat
			capacity
Minimum ambient			of
temperature during		No. of	fertilizer	Plant
experiment	Soil	fertilizer	units	survival
DAP*	C.°	type	units**	(Kcal/gC.°)	rate
1-7; 8-12	4-5	Sand	0	0	27/36-
					75%
18-28; 12-17	7-8	Sand	56	1380	31/36-
					86%
29-36; 45-55; 56-63	9-10	Clay	0	0	19/36-
					53%
37-44	11	Clay	83	1380	27/36-
					75%
*DAP, Day after planting.
**Average value. Fertilizer units contained 25 g of water.

Example 8

Fertilizer Units as Fertilizer Source for Plants in Volcanic Origin Soil and Tropical Climate

A field trial was conducted in Cartago, Costa-Rica (N9.862039, W83.898665). Local soil is classified as Andisol, a volcanic origin soil with graded soil particle distribution (Sand—50%, Silt—20% and Clay—30%), low pH (5.5), low salinity level (electrical conductivity—0.1 mS/cm), low CEC (13.5 meq/L) and high organic matter (3.1%). The climate is defined as tropical with a high annual precipitation rate (400-600 cm per year), high humidity and steady high temperatures (26-11° C.).

Celery and Lettuce seedlings, representative leafy crops, were transplanted on Day 0. The crops were fertilized by fertilizer units similar to the type described in Example 6 or solid commercial fertilizer (YaraMila™ Hydrocomplex 12:11:18+Mg+Micro).

Amounts of fertilizer units and solid commercial fertilizer were calculated so that all plants received equal amounts of nitrogen: 2.5 and 3 g of N per plant for celery and lettuce, respectively. Thirty three fertilizer units per meter at 25 cm deep and 66 fertilizer units per meter at 15 cm deep were applied in the celery plot. Eighty three fertilizer units per meter at 15 cm deep were applied in the lettuce plot. Solid fertilizer was applied after plant transplantation.

Marketable yield of each crop was evaluated on Day 45. FIG. 48 presents the combined marketable yield of celery and lettuce. Data is presented as cumulative percentage of yield relative to control median of each treatment. Plants fertilized with fertilizer units were significantly larger compared to plants fertilized with the commercial solid fertilizer.

Example 9

Microbial Examination of Fertilizer Units

A laboratory analysis of microbial colonies on the surface and inside fertilizer units was conducted to measure the transport of microbial communities from the soil to the fertilizer unit surface and into the internal zone.

Microbial activity is required in controlling urea mineralization and enhancing biodegradability of the product. Fertilizer units were collected from the root zone of the experiments described in examples 5 and 7. The number of microbial colonies was measured on the fertilizer unit surface and within the internal zone after roots penetrated and developed within it. A control group included new fertilizer units that were not in contact with soil and plant roots. High concentration of microbial colonies was found on the surface and within the internal zone for both soil types and experimental conditions. Surface concentrations for fertilizer units ranged between 2.2×10⁴ to 2.9×10⁵ CFU/cm². Internal zone concentrations for fertilizer units ranged between 3.5×10⁶ to 1.3×10⁵ CFU/0.1 g. Internal zone concentrations for new fertilizer units (control) were below 10 CFU/1 g. The results suggested unrestricted transport of microbial communities from the soil towards the fertilizer unit surface and its inner zone.

Materials and Methods

The outside of the fertilizer units were washed with running tap water for about one minute and then washed with sterile water. Each washed sample was placed into a sterile bag containing 100 mL of sterile water and manually shaken for about 3 minutes. The rinsing liquid in appropriate dilutions was examined for microbial count. The fertilizer unit samples were then aseptically cut and about 0.1 g of inner contents was removed, transferred to a tube with 10 mL of sterile water and vortexed for extraction of microorganisms. The extract was diluted and examined for microbial count. Microbial count was determined using the pour plate method with tryptic soy broth and incubation at 30-35° C. for two days. After incubation the number of microbial colonies was counted.

Discussion

High rates of inefficient agrochemical use are attributed to unknown root distribution, spatial variability in soil structure and texture (i.e. mineral and organic matter content), temporal variability of soil conditions (i.e. temperature, moisture, pH, aeration and salinity), temporal changes in plant demands of fertilizers and agrochemicals (i.e. species, development stage, root morphology), and climatic fluctuations throughout the growing season (i.e. rainfall, temperature, humidity, radiation and wind).

Soil-less medium, where optimal conditions for efficient uptake by roots are maintained, is implemented solely in small scale containers in greenhouses. This practice is not feasible as a solution for large scale fields.

An overall goal of the present invention is supplying fertilizers and other agrochemicals (e.g. nitrogen, phosphorus, potassium, fungicides, insecticides, etc.) directly to plant roots at required amounts and timing regardless of soil and crop types and conditions.

Availability and uptake of fertilizer from commercial products are dramatically affected by soil due to the pH and reactions with various cations. The present invention relates to universal additives and formulations that are not affected by soil type or pH, due to the formation of an artificial environment.

A problem with the additions of small SAP beads (super absorbent polymer with diameter of 1 cm) is a fast diffusion of the additives into the soil. In contrast to the SAP beads that are currently used, the unit for delivery of agrochemicals to the roots of a plant of the present invention have a bigger size (in some embodiments, a fully hydrated volume greater than 600 ml), which prevents this problem. Aspects of the present invention also prevent properties from changing due to salts entering the soil. Furthermore, the concepts herein based on the formation of an artificial environment in the field, in contrast to other technology that use hydrogels as a solid replacement.

The an artificial environment formed by the units of the present invention encourages root growth and development within the unit, which enhances and promotes efficient nutrient uptake. Thus, plants fertilized using the units of the present invention can grow faster and/or produce a greater yield than crops fertilized by traditional methods. The artificial environment formed by the units of the present invention mitigates the effects of suboptimal soil conditions by, for example, providing a root development zone which minimizes root growth resistance, provides nutrients, maintains moisture levels, and protects from the effects of low ambient temperature.

Aspects of the present invention that are advantageous and unique over current technologies and practices include but are not limited to:

• • Universality—embodiments of the present invention are not dependant on temporal and spatial variations of soil, crop and weather.
  • Simplicity—embodiments of the present invention relate to a single application using conventional equipment.
  • Economy—embodiments of the present invention save labor and the amount of agrochemical input (fertilizers and otheragrochemicals, and energy) for the farmer.
  • Sustainability—embodiments of the present invention protect the environment (water bodies and atmosphere) from contamination as a result of leaching, runoff and volatilization of agrochemicals.
  • Yield—embodiments of the present invention enhance plant growth rates and yield.

The present invention provides artificial environments that encourage or promote root growth or development in different soil types. Root growth and development are a function of moisture, oxygen, nutrients and mechanical resistance. The data herein showed that alginate preformed markedly well with respect to root development. However, additional formulations (semi-synthetic CMC and fully synthetic-acrylic acid and acrylamide) show root growth as well. Aspects of the present invention relate to artificial environments that provide, moisture and nutrients, while being mechanically resistant and permeable to oxygen. The data herein described herein demonstrated the ability of the units of the invention to deliver water and nutrients to plants throughout the growing season leading to enhanced plant growth. The data described herein further demonstrated that the units of the invention can be used to successfully deliver nutrients to plants in variable soil types and variable climate conditions.

REFERENCE

• Drew M. C., 1997. Oxygen deficiency and root metabolism: Injury and acclimation under hypoxia and anoxia. ANNUAL REVIEW OF PLANT PHYSIOLOGY AND PLANT MOLECULAR BIOLOGY Volume: 48 Pages: 223-250.
• Habarurema and Steiner, 1997. Soil suitability classification by farmers in southern Rwanda. Geoderma Volume 75, Issues 1-2, Pages 75-87
• Hopkins H. T., 1950. Growth and nutrient accumulation as controlled by oxygen supply to plant roots. Plant Physiology, 25(2): 193-209.
• Nicholson S. E. and Farrar T. J., 1994. The influence of soil type on the relationships between NDVI, rainfall, and soil moisture in semiarid Botswana. I. NDVI response to rainfall. Remote Sensing of Environment Volume 50, Issue 2, Pages 107-120
• Shaviv A., Mikkelsen R. L. 1993. Controlled-release fertilizers to increase efficiency of nutrient use and minimize environmental degradation—A review. Fert. Res. 35, 1-12.

Claims

1. A unit for delivery of agrochemicals to the roots of a plant comprising:

i) one or more root development zones, and

ii) one or more agrochemical zones containing at least one agrochemical,

wherein the agrochemical zones are formulated to release the at least one agrochemical into the root development zones in a controlled release manner when the root development zones are swelled, and

wherein the weight ratio of the root development zones to the agrochemical zones in a dry unit is 0.05:1 to 0.32:1 or wherein the total volume of the root development zones in the unit is at least 0.2 mL when the unit is fully swelled.

2. (canceled)

3. (canceled)

4. (canceled)

5. The unit of claim 1, wherein the weight ratio of the root developments zones to agrochemical zones in a dry unit is 0.05:1, 0.1:1, 0.15:1, 0.2:1, 0.25:1, or 0.3:1.

6. The unit of claim 5, wherein the total volume of the root development zones in the unit is at least at least 0.2 mL, at least 0.5 mL, at least 1 mL, at least 2 mL, at least 5 mL, at least 10 mL, at least 20 mL, at least 30 mL, at least 40 mL, at least 50 mL, at least 60 mL, at least 70 mL, at least 80 mL, at least, 90 mL, at least 100 mL, at least 150 mL, at least 200 mL, at least 250 mL, at least 300 mL, at least 350 mL, at least 400 mL, at least 450 mL, at least 500 mL, at least 550 mL, at least 600 mL or larger than 600 mL when the unit is fully swelled.

7. (canceled)

8. (canceled)

9. The unit of claim 5, wherein roots of a plant are capable of growing within the root development zones when the root development zones are swelled, and wherein the total volume of the root development zones when the unit is 1%-100% swelled is large enough to contain at least 10 mm of a root having a diameter of 0.5 mm.

10. (canceled)

11. The unit of claim 1, wherein the unit has a dry weight of 0.1 g to 20 g and wherein the total weight of the agrochemical zones of the unit is 0.05 to 5 grams.

12. (canceled)

13. The unit of claim 1, wherein the unit is in the shape of a cylinder, polyhedron, cube, disc, or sphere.

14. (canceled)

15. (canceled)

16. (canceled)

17. (canceled)

18. The unit of claim 1, wherein the agrochemical zones and the root development zones are adjoined, or wherein the agrochemical zones are partially contained within the root development zones such that the surface of the unit is formed by both the root development zones and the agrochemical zones.

19. (canceled)

20. The unit of claim 18, wherein the unit is a bead comprising an external zone surrounding an internal zone, wherein the root development zones form the external zone and the agrochemical zones form the internal zone.

21. The unit of claim 20, wherein the unit comprises one root development zone and one agrochemical zone.

22. The unit of claim 21, wherein the root development zones comprise a super absorbent polymer (SAP).

23. The unit of claim 22, wherein the root development zones are capable of absorbing at least about 10, 15, 20, 25, 30, 35, 40, 45, 50, 75, 80, 85, 90, 95, 100, 200, 300, 400, 500, or 1000 times their weight in water.

24. The unit of claim 23, wherein the root development zones are permeable to oxygen, or wherein the root development zones comprise an aerogel, a hydrogel or an organogel, or wherein the root development zones further comprise a polymer, a porous inorganic material, a porous organic material, or any combination thereof.

25. (canceled)

26. (canceled)

27. (canceled)

28. (canceled)

29. (canceled)

30. The unit of claim 20, wherein the agrochemical zones further comprise an aerogel, a hydrogel, an organogel, a polymer, a porous inorganic material, a porous organic material, or any combination thereof.

31. (canceled)

32. (canceled)

33. (canceled)

34. (canceled)

35. (canceled)

36. (canceled)

37. (canceled)

38. (canceled)

39. (canceled)

40. The unit of claim 30, wherein the root development zones comprise a synthetic hydrogel, a natural carbohydrate hydrogel, or a pectin or protein hydrogel, or any combination thereof.

41. The unit of claim 40, wherein the root development zones comprise a natural super absorbent polymer (SAP), a poly-sugar SAP, a semi-synthetic SAP, a fully-synthetic SAP, or any combination thereof, or wherein the root development zones further comprise at least one oxygen carrier that increases the amount of oxygen in the root development zones compared to corresponding root development zones not comprising the oxygen carrier.

42. (canceled)

43. The unit of claim 41, wherein the agrochemical zones comprise an organic polymer, a natural polymer, or an inorganic polymer, or any combination thereof.

44. The unit of claim 1, wherein the agrochemical zones are partially or fully coated with a coating system that dissolves into the root development zones when the root development zones are swelled and slows the rate at which the at least one agrochemical dissolves into the root development zones when the root development zones are swelled.

45. (canceled)

46. (canceled)

47. (canceled)

48. The unit of claim 1, wherein the at least one agrochemical is:

i) at least one fertilizer compound;

ii) at least one pesticide compound,

iii) at least one hormone compound;

iv) at least one drug compound;

v) at least one chemical growth agents;

vi) at least one enzyme;

vii) at least one growth promoter; and/or

viii) at least one microelement.

49. A method of growing a plant, comprising adding at least one unit of claim 1 to the medium in which the plant is grown.

50. (canceled)

51. (canceled)

52. A method of generating an artificial zone with predetermined chemical properties within the root zone of a plant, comprising:

i) adding one or more units to the root zone of the plant; or

ii) adding one or more units to the anticipated root zone of the medium in which the plant is anticipated to grow,

wherein at least one of the one or more units is as defined in claim 1.