Abstract: The present invention relates to a method of separating amino acids from an aqueous solution comprising amino acids as well as proteins and/or protein decomposition products by combining phosphoric acid with the aqueous solution to precipitate an amino acid monophosphate. The precipitate so formed may be separated from the aqueous solution and used as such, e.g. in plant fertilizer compositions. The precipitate may be redissolved in a suitable liquid, after which phosphate and amino acid may be separated following conventional methods. In either case, the present invention enables highly selective precipitation of arginine and/or lysine monophosphate as crystals.

Abstract: The present invention relates to a fertilizer comprising at least one basic L-amino acid, such as arginine or lysine, wherein a substantial portion of the basic L-amino acid content is present as its monophosphate. The basic L-amino acid phosphate may be combined with a binder and/or provided with an outermost layer acting as a coating. The invention also relates to a method of enhancing the growth of a plant by making a basic L-amino acid phosphate available to the plant.

Abstract: The present invention relates to a fertilizer composition comprising nitrogen and phosphorus, wherein nitrogen is provided by basic L-amino acid(s) complexed to polyphosphate(s). The complex may be precipitated with multivalent metal ion(s) to provide a solid phase fertilizer composition. The basic L-amino acid is advantageously L-arginine and/or L-lysine. The fertilizer composition is capable of providing controlled release of nitrogen during prolonged periods of time.