Abstract: The present invention relates to a solid water soluble fertilizer composition containing one or more fertilizer materials and a phosphate free, organic acid which is solid at ambient temperatures. The fertilizer materials include primary macro nutrients, secondary macro nutrients, micro nutrients and mixtures thereof. The organic acid has a water solubility of at least 10 g/l (at 25° C.) and an acidifying effect in the range of 0.5 to 1.3 g HCO3−/g acid. The acidifying effect is defined as the amount of HCO3− that can be transformed into H2CO3 per gram of acid and is calculated in accordance with the following formula: 61 ⁢ n M w , acid wherein Mw,acid is the molecular weight of said acid and n represents the number of dissociation constants (i.e., pKa values) of the acid below the value of 6.35.

Abstract: A controlled release fertilizer is provided which exhibits a Gaussian nutrient release rate pattern. The fertilizer composition includes a granular nutrient core material having a single layer coating of a substantially water-insoluble, uniform, substantially continuous polymer film thereon. Processes are also provided for producing the fertilizer compositions. Methods are also provided for treating plants with the fertilizer compositions.

Abstract: A controlled release fertiliser composition is provided having a fertiliser compound in a granular core with a coating applied on the core material. The fertiliser composition is structured to enable a cumulative release of fertiliser compound of less than 10% of the total weight of the fertiliser compound in the granular core within 30 days after exposure of the fertiliser composition to moisture and the coating consists of a single layer of a uniform, substantially continuous polymer film which is present on at least 90% of the granular core material A process is also provided for producing the fertiliser composition.