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Continual application of mineral fertilizer and manures to meet crop production goals has resulted in the buildup of soil P concentrations in many areas. A rainfall simulation study was conducted to evaluate the effect of the application of P sources differing in water-soluble P (WSP) concentration on P transport in runoff from two grassed and one no-till soil (2 m(2) plots). Triple superphosphate (TSP)-79% WSP, low-grade single superphosphate (LGSSP)-50% WSP, North Carolina rock phosphate (NCRP)-0.5% WSP, and swine manure (SM)-30% WSP, were broadcast (100 kg total P ha(-1)) and simulated rainfall (50 mm h(-1) for 30 min of runoff) applied 1, 7, 21, and 42 d after P source application. In the first rainfall event one d after fertilizer application, dissolved reactive P (DRP) and total P (TP) concentrations of runoff increased (P < 0.05) for all soils with an increase of source WSP; with DRP averaging 0.27, 0.50, 14.66, 41.69, and 90.47 mg L(-1); and total P averaging 0.34, 0.61, 19.05, 43.10, and 98.06 mg L(-1) for the control, NCRP, SM, LGSSP, and TSP, respectively. The loss of P in runoff decreased with time for TSP and SM, such that after 42 d, losses from TSP, SM, and LGSSP did not differ. These results support that P water solubility in P sources may be considered as an indicator of P loss potential. 相似文献
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Francirose Shigaki Peter J. A. Kleinman John P. Schmidt Andrew N. Sharpley Arthur L. Allen 《Journal of the American Water Resources Association》2008,44(6):1500-1511
Abstract: Drainage ditches can be a key conduit of phosphorus (P) between agricultural soils of the Atlantic Coastal Plain and local surface waters, including the Chesapeake Bay. This study sought to quantify the effect of a common ditch management practice, sediment dredging, on fate of P in drainage ditches. Sediments from two drainage ditches that had been monitored for seven years and had similar characteristics (flow, P loadings, sediment properties) were sampled (0‐5 cm) after one of the ditches had been dredged, which removed fine textured sediments (clay = 41%) with high organic matter content (85 g/kg) and exposed coarse textured sediments (clay = 15%) with low organic matter content (2.2 g/kg). Sediments were subjected to a three‐phase experiment (equilibrium, uptake, and release) in recirculating 10‐m‐long, 0.2‐m‐wide, and 5‐cm‐deep flumes to evaluate their role as sources and sinks of P. Under conditions of low initial P concentrations in flume water, sediments from the dredged ditch released 13 times less P to the water than did sediments from the ditch that had not been dredged, equivalent to 24 mg dissolved P. However, the sediments from the dredged ditch removed 19% less P (76 mg) from the flume water when it was spiked with dissolved P to approximate long‐term runoff concentrations. Irradiation of sediments to destroy microorganisms revealed that biological processes accounted for up to 30% of P uptake in the coarse textured sediments of the dredged ditch and 18% in the fine textured sediments of the undredged ditch. Results indicate that dredging of coastal plain drainage ditches can potentially impact the P buffering capacity of ditches draining agricultural soils with a high potential for P runoff. 相似文献
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