|Edwards, J - DECEASED USDA, ARS|
Submitted to: International Conference FGD and Other Synthetic Gypsum Proceedings
Publication Type: Proceedings
Publication Acceptance Date: September 18, 2007
Publication Date: October 9, 2006
Citation: Workshop regarding Research and Demonstration of Agricultural Uses of Gypsum and Other FGD Materials, St. Louis, MO Sept 14-16, 2006 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.