Source-related transport of phosphorus in surface runoff.
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.
Shigaki
Francirose
F
Dep. Ciência do Solo, ESALQ, Univ. of São Paulo, Piracicaba, SP, Brazil.
Sharpley
Andrew
A
Prochnow
Luís Ignácio
LI
D000383:Agriculture; D000818:Animals; D000829:Animals, Domestic; D001692:Biological Transport; D004784:Environmental Monitoring; D005308:Fertilizers; D006863:Hydrogen-Ion Concentration; D008372:Manure; D009657:North Carolina; D010758:Phosphorus / Q000032:analysis*; D011891:Rain; D012989:Soil Pollutants / Q000032:analysis*; D012995:Solubility; D014872:Water Movements; D014873:Water Pollutants / Q000032:analysis*
D005308:Fertilizers; D008372:Manure; D012989:Soil Pollutants; D014873:Water Pollutants; D010758:Phosphorus