Method of preparing a controlled release fertilizer

1. A method of preparing a controlled release fertilizer, comprising:

obtaining condensed corn fermentation solubles; and

treating said condensed corn fermentation solubles with a source of magnesium and a source of phosphate to obtain a controlled release fertilizer comprising magnesium ammonium phosphate and residual bacterial cell mass,

wherein the condensed corn fermentation solubles comprise a byproduct liquor from fermentative production of at least one amino acid selected from the group consisting of arginine, histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, valine, glycine, serine, cysteine, tyrosine, alanine, aspartic acid, glutamic acid, proline, asparagine and glutamine.

2. The method of claim 1 , wherein the condensed corn fermentation solubles comprise a byproduct liquor from fermentative production of at least one amino acid selected from the group consisting of glutamic acid, lysine, threonine and tryptophan.

3. The method of claim 1 , wherein the condensed corn fermentation solubles comprise a byproduct liquor from fermentative production of at least one amino acid selected from the group consisting of lysine and threonine.

4. The method of claim 1 , wherein treating the condensed corn fermentation solubles comprises:

adding the source of phosphate to the condensed corn fermentation solubles;

adjusting pH of the condensed corn fermentation solubles; and

adding the source of magnesium to the condensed corn fermentation solubles.

5. The method of claim 1 , wherein treating the condensed corn fermentation solubles comprises:

adding the source of phosphate to the condensed corn fermentation solubles to obtain an intermediate mixture;

adjusting pH of the intermediate mixture; and

adding the source of magnesium to the pH-adjusted intermediate mixture to obtain the controlled release fertilizer.

6. The method of claim 5 , wherein adding the source of phosphate comprises adding a source of phosphate soluble in the condensed corn fermentation solubles.

7. The method of claim 5 , wherein adding the source of phosphate comprises adding at least one source of phosphate selected from the group consisting of phosphoric acid, monoammonium phosphate, diammonium phosphate, sodium salts of phosphoric acid, and potassium salts of phosphoric acid.

8. The method of claim 5 , wherein adjusting pH comprises adjusting pH to a value in a range of from 6.0 to 8.6.

9. The method of claim 5 , wherein adjusting pH comprises adjusting pH to a value in a range of from 6.0 to 7.0.

10. The method of claim 5 , wherein adjusting pH comprises adjusting pH by adding at least one member selected from the group consisting of sources of sodium, sources of potassium and sources of ammonium.

11. The method of claim 5 , wherein adjusting pH comprises adjusting pH by adding at least one member selected from the group consisting of sodium hydroxide, calcium oxide, potassium hydroxide and ammonium hydroxide.

12. The method of claim 5 , wherein adding the source of magnesium comprises adding at least one member selected from the group consisting of magnesium oxide and magnesium hydroxide.

13. The method of claim 5 , wherein the pH after addition of the source of magnesium is in a range of from 6.2 to 9.0.

14. The method of claim 5 , wherein the pH after addition of the source of magnesium is in a range of from 6.2 to 8.0.

15. The method of claim 5 , wherein ammonium in the condensed corn fermentation solubles, the source of phosphate and the source of magnesium are present in amounts sufficient to provide:

ammonium and phosphate in a molar ratio of from 20:1 to 1:20; and

magnesium and phosphate in a molar ratio of from 10:1 to 1:10.

16. The method of claim 1 , further comprising drying the controlled release fertilizer.

17. The method of claim 16 , further comprising granulating the dried controlled release fertilizer.