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United States Department of Agriculture

Agricultural Research Service

Title: Effects of various soil amendments on soil test P values

item Brauer, David - Dave
item Aiken, Glen
item Pote, Daniel - Dan
item Livingston, Stanley
item Norton, Lloyd
item Way, Thomas - Tom
item Edwards, J

Submitted to: International Conference FGD and Other Synthetic Gypsum Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 9/18/2007
Publication Date: 10/9/2006
Citation: Workshop regarding Research and Demonstration of Agricultural Uses of Gypsum and Other FGD Materials, St. Louis, MO Sept 14-16, 2006

Interpretive Summary:

Technical Abstract: Applications of animal manures have increased soil test P values in many parts of the United States, especially where concentrated animal feeding operations dominate, and thus increased the risk that soil P will be transferred to surface water and decrease water quality. To continue farming in these areas, landowners need tools to reduce the risk of P moving off agricultural land. A field experiment was conducted near Kurten, TX to evaluate the effectiveness of soil amendments for reducing soil test P values. The soil is a Zulch fine sandy loam (thermic Udertic, Paleustalfs) with Bray1 P values exceeding 1,000 mg P/ kg. Soils were amended annually for 3 years (1999 to 2001) with 1.5 and 5 Mg gypsum/ha, 1.4 Mg alum/ ha or 24.4 Mg / ha of a waste paper product (as a source of Al). Soil Bray1 P and dissolved reactive P levels were monitored from 1999 to 2004. None of the soil amendment treatments had a significant effect on Bray1 P values. Only annual additions of 5 Mg gypsum/ ha from 1999 to 2001 significantly reduced soil dissolved reactive P values. Decreases in soil dissolved reactive P values by the higher rate of gypsum applications were associated with increases in readily soluble Ca levels and Ca additions that were equal or exceeded Bray1 P values. A second experiment was conducted at Booneville AR on Leadvale silt loam with moderate levels of soil P. Soil was amended with 0, 22, 44, or 88 Mg waste paper /ha to supply approximately 90, 170, or 350 kg of Al/ ha, respectively. One year after additions, there was a strong negative correlation between waste paper application rates and soil bulk density, and a strong positive correlation between rates and total soil C content. Soil bulk density and total C two years after additions, and soil DRP and Bray1-P were not affected by waste paper additions. These results support the hypothesis that decreases in P runoff from soils receiving waste paper additions were likely due to changes in soil organic matter and bulk density, rather than changes in the chemical forms of soil P.

Last Modified: 10/20/2017
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