Submitted to: Biology and Fertility of Soils
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: June 20, 2003
Publication Date: November 20, 2003
Citation: He, Z., Honeycutt, C.W., Griffin, T.S. 2003. Enzymatic hydrolysis of organic phosphorus in extracts in resuspensions of swine manure and cattle manure. Biology and Fertility of Soils. 38: 78-83 Interpretive Summary: Animal manure can be a valuable resource of phosphorus (P) for plant growth. Organic phosphates are considered available to plants and microorganisms if they can be converted to inorganic P through a process called hydrolysis. Therefore, investigating the susceptibility of manure organic P to hydrolysis will increase our understanding of the availability yof manure organic P to plants and microorganisms (i.e. bioavailability). I this study, we demonstrated that a scheme of sequential hydrolysis of organic P can be used to investigate the bioavailability of animal manure P. Our data indicate that storage of a swine manure at a temperature of 4 C or a cattle manure at 22 C for about a year did not significantly change the availability of P. However, more P in these manures became soluble. This form of P might not be readily available for plant growth, but may be easily transported in surface runoff. The implications of this finding require further investigation.
Technical Abstract: Animal manure can be a valuable resource of P for plant growth. Organic phosphates (Po) are considered bioavailable if they can be hydrolyzed to inorganic P. Therefore, investigation of the susceptibility of manure Po to hydrolysis may increase our understanding of manure Po bioavailability. In this study, we demonstrated that three orthophosphate-releasing enzymes, acid phosphatase from wheat germ, alkaline phosphatase from bovine intestinal mucosa, and fungal phytase from Aspergillus ficcum, were able to hydrolyze certain amounts of Po in animal manure. A scheme of sequential enzymatic release of manure organic P in manure was developed and used to investigate the changes in swine and cattle manure P distribution after storage at temperatures of -20 C, 4 C or 22 C for about a year. Assuming the P species in manure maintained at -20 C remained unchanged (i. e. similar to those in fresh manure), bioavailable P (inorganic P and enzyme hydrolysable Po) in swine manure remained relatively constant, while soluble but enzymatically unhydrolysable organic P (Pue) increased from 7.2% to 32.1% of total P (Pt) after storage. In cattle manure, bioavailable P decreased from 71.6% to 62.9% of Pt, and Pue increased from 21.7% to 37.2% of Pt after storage. These data indicate that manure P solubility increases with storage, but the increase may not arise from biologically available forms of P.