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ARS Home » Northeast Area » University Park, Pennsylvania » Pasture Systems & Watershed Management Research » Research » Publications at this Location » Publication #139525
Title: EFFECT OF MANURE MANAGEMENT ON C EVOLUTION AND WATER EXTRACTABLE P

Author
item Stout, William
item Dell, Curtis
item SCHNABEL, R - ARS DECEASED

Submitted to: Communications in Soil Science and Plant Analysis
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/1/2003
Publication Date: 11/1/2003
Citation: Stout, W.L., Dell, C.J., Schnabel, R.R. 2003. Effect of manure management on C evolution and water extractable P. Communications in Soil Science and Plant Analysis. 34:2901-2912.

Interpretive Summary: Soils with excessive P levels due to manure application are an environmental concern because water extractable P (WEP) in runoff from these soils can contribute to increased amounts of P in surface water, which can contribute to eutrophication in freshwater. Phosphorus-based manure management is an option to reduce WEP and thereby reduce agricultural P runoff. In P based manure management, manure is applied to meet the P needs of a crop or not to exceed a given soil test level. Because P based manure management does not supply enough N to meet the needs of the crop, additional fertilizer N needs to be applied. Fertilizer N applied to soils increases the mineralization of organic matter and lowers soil pH, and therefore may affect the solubility of soil inorganic and organic P pools. The extent to which this may affect WEP or plant P availability is not known. Thus, we conducted a laboratory and greenhouse study to determine the effects of P based manure management on WEP and short-term P plant availability. We found that increased acidity due to nitrogen fertilizer application significantly increased the formation of WEP where there was a large amount of calcium phosphates in the soil due to manure applications. This means that soil pH will have to be maintained at high levels so that P based manure management does not have the unintended consequence of forming high levels of WEP and inadvertently increasing the risk of phosphorus loss to streams.

Technical Abstract: Soils with excessive P levels due to manure application are an environmental concern because water extractable P (WEP) in runoff from these soils can contribute to increased amounts of P in surface water, which can contribute to eutrophication in freshwater. Phosphorus-based manure management is an option to reduce WEP and thereby reduce agricultural P runoff. In P based manure management, manure is applied to meet the P needs of a crop or not to exceed a given soil test level. Because P based manure management does not supply enough N to meet the needs of the crop, addition fertilizer N needs to be applied. Fertilizer N applied to soils increases the mineralization of organic matter and lowers soil pH,and therefore may affect the solubility of soil inorganic and organic P pools. The extent to which this may affect WEP or plant P availability is not known. Thus, we conducted a laboratory and greenhouse study to determine the effects of P-based manure management on WEP and short-term P plant availability. P based manure management had no significant effect on the shift of organic P to WEP, but the increased acidity due to urea hydrolysis had a significant effect on the solubilization of P from the Ca-bound IP pool, thereby increasing WEP. This could be a significant consideration where Ca-bound IP dominates IP, P based manure management is implemented, and increased WEP is subject to export to surface waters via surface runoff.