Effects of long-term phosphorus fertilization and winter cover cropping on soil phosphorus transformations in less weathered soil |
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Authors: | S Kuo B Huang R Bembenek |
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Institution: | (1) Puyallup Research and Extension Center, Washington State University, 7612 Pioneer Way E., Puyallup, WA 98371-4998, USA;(2) Department of Crop and Soil Sciences, College of Agriculture and Home Economics, Washington State University, Pullman, WA, USA |
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Abstract: | Information concerning sources and sinks of available P in soil is needed to improve soil P management and protect water quality. This study, conducted from 1989 to 1998 on a Sultan silt loam soil (Aquantic Xerochrept), determined the annual P removal rate by corn (Zea mays L.) and P transformation as affected by P rate and winter cover cropping. Treatments included two P rates (0 and 44 kg P ha–1) applied to corn at planting each year. All cover crops received 19.6 kg P ha–1 at seeding each fall. Also included was a control without any cover crop and with no P addition. Corn yield and P uptake were affected by P fertilizer additions, but not by cover crops. A fairly constant amount of P was supplied from indigenous soil P when no external P was added. When the amount of P added exceeded that removed by corn, the excess P was converted mainly to NaOH-extractable inorganic P (NaOH-Pi). When the amount of P applied was below that removed by corn, indigenous soil NaOH-Pi acted as a source of available P for the plant. With no reduction of organic P (Po) extractable by NaOH or NaHCO3, the contribution from Po to the available P pool appeared limited. The role of NaOH-Pi in P availability in the soil was substantiated by its significant correlation with labile NH4Cl-extractable P (NH4Cl-P; r2 =0.60, P <0.001) or NaHCO3-Pi (r2 =0.81, P <0.001) pools. The NaOH-Pi for the soil reflected the changes in soil P resulting from past fertilizer P input and P removal by the crops.Scientific Paper Number 0005-34 |
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Keywords: | Phosphorus Transformation Corn Cover crop Sequential extractions |
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