Source-Related Transport of Phosphorus in Surface Runoff
2006
Shigaki, Francirose | Sharpley, Andrew | Prochnow, Luis Ignácio
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 m² 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.
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