Abstract: This invention provides methods of enhancing plant growth or yield, comprising exposing soil to hydrogen gas (H2), and growing plants in the soil. The H2 gas employed can be generated by electrolysis of water, produced by H2 evolving microorganisms, and/or produced by legumes. In accordance with the invention, soil can be exposed to H2 and plants then grown in it, or H2 can be applied directly to soil in which plants are already growing. In one embodiment, the invention comprises obtaining an aqueous extract from H2-treated soil, and applying the extract to soil, seeds, and or plant roots.

Abstract: This invention provides methods of enhancing plant growth or yield, comprising exposing soil to hydrogen gas (H2), and growing plants in the soil. The H2 gas employed can be generated by electrolysis of water, produced by H2 evolving microorganisms, and/or produced by legumes. In accordance with the invention, soil can be exposed to H2 and plants then grown in it, or H2 can be applied directly to soil in which plants are already growing. In one embodiment, the invention comprises obtaining an aqueous extract from H2-treated soil, and applying the extract to soil, seeds, and or plant roots.

Abstract: This invention provides methods of enhancing plant growth or yield, comprising exposing soil to hydrogen gas (H2), and growing plants in the soil. The H2 gas employed can be generated by electrolysis of water, produced by H2 evolving microorganisms, and/or produced by legumes. In accordance with the invention, soil can be exposed to H2 and plants then grown in it, or H2 can be applied directly to soil in which plants are already growing. In one embodiment, the invention comprises obtaining an aqueous extract from H2-treated soil, and applying the extract to soil, seeds, and or plant roots.

Abstract: A method and apparatus for measuring differential and absolute concentrations of a selected gas, preferably oxygen, in two flowing gas streams is described. A reference gas and a sample gas in separate gas flow paths are passed at selected temperature, pressure and flow rate over a pair of gas sensors, connected in series with their cathodes or anodes connected together, which produce output signals proportional to the differential selected gas concentration between the sensors and the absolute selected gas pressure in each sensor. The output signals may be amplified and recorded by any conventional means.

Abstract: A method and apparatus for rapidly measuring nitrogenase activity of a nitrogen fixing plant growing in a medium in a non-porous container, is described. Gas containing hydrogen is sampled at the surface of the medium at a rate approximately equal to the rate of hydrogen diffusion from the medium, and the sample is passed to a hydrogen sensor where it is measured and nitrogenase activity is determined therefrom.

Abstract: An apparatus and method for measuring differential oxygen concentration between two flowing gas streams is described. A reference gas and a sample gas in separate gas flow paths are passed, at selected temperature, pressure and flow rate over a respective one of a pair of electrically connected oxygen sensors which produce an output signal proportional to the differential oxygen concentration between the sensors. The output signal may be amplified and recorded by any conventional means. An internal calibration system is also described.

Abstract: An apparatus for electrolytically generating small volumes of a selected gas such as hydrogen for introduction into a flowing gas stream is described. The gas stream flows through an electrolytic cell wherein the selected gas is generated at an electrode and a portion of the gas stream is diverted through a needle valve and a non-conducting capillary with a small orifice to deliver gas to the electrodes so as to dislodge the selected gas bubbles forming thereon and carry them into the flowing gas stream. To maintain the level of electrolyte in the cell, the cell is connected by a narrow tube to a reservoir of electrolyte. The reservoir has a volume and surface area many times greater than that of the cell and the gas volume above the reservoir is maintained at the pressure and composition of the gas stream entering the electrolytic cell.

Abstract: A non-invasive method and apparatus are described for measuring the oxygen concentration in the infected cells of the nodules of nitrogen fixing plants in the laboratory or field. In many cases, this information can be used to estimate the nitrogenase activity, and therefore the nitrogen fixation rate, in these nodules since recent studies have shown that the oxygen concentration limits and controls nitrogenase activity under most environmental conditions. Using the same apparatus, a method to measure nodule respiration and nodule oxygen permeability is also described. The nodule oxygen concentration in the infected cells of nodules is maintained at very low levels and has not been measurable previously by non-invasive techniques.