Submitted to: Journal of Environmental Quality
Publication Type: Peer reviewed journal
Publication Acceptance Date: 11/12/2003
Publication Date: 5/15/2004
Citation: Smith, D.R., Moore Jr, P.A., Maxwell, C.V., Haggard, B.E., Daniel, T.C. 2004. Reducing phosphorus runoff from swine manure with dietary phytase and aluminum chloride. Journal of Environmental Quality. 33:1048-1054. Interpretive Summary: Fertilization with manure may contribute to the degradation of U. S. surface water. Phosphorus from manure applications is of particular concern. Producers can use dietary modification to reduce the total amount of phosphorus in manure, or manure amendments to precipitate phosphorus in manure. This study was conducted to compare these two methods of phosphorus reduction on phosphorus runoff following fertilization with manure. Both dietary modification with the phytase enzyme and manure amendments with aluminum chloride reduced phosphorus in manure. Phytase manure increased phosphorus runoff following fertilization with manure by 24%. Aluminum chloride manure amendments decreased phosphorus runoff by 42% compared to normal manure. When both dietary modification with phytase and aluminum chloride manure amendments were used together, phosphorus runoff was reduced as much as 57% compared to fertilization with normal manure. These results are very promising, and indicate that using both of these treatments at swine facilities could significantly decrease the amount of phosphorus delivered to a waterbody, particularly in watersheds with intensive swine production.
Technical Abstract: Fertilization with manure contributes to eutrophication as a result of phosphorus (P) losses. Dietary modification can reduce total P in manure and manure amendments can be used to reduce P solubility in manure. This study was conducted to compare dietary modification and manure amendments on P runoff from fertilization with swine manure. Swine were fed a normal or phytase diet, and aluminum chloride (AlCl3) was added to manure at 4 rates between 0 and 0.75%. Phytase diets resulted in reductions of 13% for total P in manure and 17% for soluble P in manure. Aluminum chloride reduced manure soluble P by as much as 73%. Phytase without AlCl3 increased P runoff following fertilization with swine manure by 24% compared to normal diet manure. Use of AlCl3 reduced P runoff by up to 42% compared control manure. When both treatments were used together reductions were higher than if AlCl3 was used alone for manure P and P runoff. Results from this study indicate that producers could use both phytase and AlCl3 to reduce the pollution potential of this valuable fertilizer resource.