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United States Department of Agriculture

Agricultural Research Service

Title: Reduction of High Soil Test Phosphorus by Crop Removal

Authors
item Eghball, Bahman
item Shanahan, John
item Varvel, Gary
item Gilley, John

Submitted to: Agronomy Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: September 1, 2003
Publication Date: November 1, 2003
Citation: EGHBALL, B., SHANAHAN, J.F., VARVEL, G.E., GILLEY, J.E. REDUCTION OF HIGH SOIL TEST PHOSPHORUS BY CROP REMOVAL. AGRONOMY JOURNAL 95:1233-1239. 2003.

Interpretive Summary: Soils with high phosphorus (P) level can contribute to excess P in runoff and the subsequent pollution of surface water. Excess P in the soil can be removed from the system by harvesting crops. Soil with varying P level as a result of annual or biennial manure or compost application was cropped to corn for four years without any P addition. In other studies under various water and N treatments, corn hybrids and soybean varieties were evaluated for grain P concentration and P removal differences. Four years of corn production without P addition reduced surface soil (0 to 6 inch) P level from 265 ppm to 171 ppm in the compost application to provide for corn N needs for two years treatment. Based on a decay equation, it would have required 10 years of crop P removal to reduce the soil P level to the original 69 ppm level before treatment application. The higher the soil test P, the sharper the decline in soil P level with years of corn production. Across two years, there was as much as 35% difference among corn hybrids for grain P removal. Corn hybrids also had different grain P concentrations indicating that corn hybrids can be selected for low P when reduced P concentration in the animal ration, and subsequently in excreted manure is desirable. Soybean grain P concentration was nearly twice that for corn but grain P removal was less for soybean than for corn. Crop P removal can significantly reduce soil P level with time. The reduction in soil P would probably be greater when the soil used has a high P adsorption capacity.

Technical Abstract: Soils with high phosphorus (P) level can contribute to excess P in runoff and the subsequent pollution of surface water. Excess P in the soil can be removed from the system by harvesting crops. The objectives of this study were to evaluate crop P removal effects on soil P reduction and to evaluate various corn (Zea mays L.) hybrids and soybean (Glycine max Merrill.) varieties for differences in grain P concentration and P removal. Soil with varying P level as a result of annual or biennial beef cattle feedlot manure or compost application was cropped to corn for four years without any P addition. In other studies under various water and N regimes, corn hybrids and soybean varieties were evaluated for grain P concentration and P removal. Four years of corn production without P addition reduced surface soil (0 to 15 cm) P level from 265 mg kg-1 to 171 mg kg-1 in the biennial N-based compost treatment. Based on a decay equation, it would have required 10 years of crop P removal to reduce the soil P level to the original 69 mg kg-1 before treatment application. The rate of decrease in soil P was greater when soil P was higher and reduced with decreasing soil P level. Across two years, there was as much as 35% difference among corn hybrids for grain P removal. The differences in P concentrations among corn hybrids indicated that they could be selected for low P when reduced P concentration in the animal ration and subsequently in excreted manure is desired. Soybean grain P concentration was nearly twice that for corn but grain P removal was less for soybean than for corn.

Last Modified: 12/22/2014
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