Phosphorus losses in subsurface flow before and after manure application to intensively farmed land.
A study was conducted to examine the loss of P in subsurface flow from three cultivated soils of varying soil P concentrations. Measurements were made in flow waters from the soils before applying manure and then 3 weeks after sowing the soils to grass. An additional measurement of P in flow waters was made 1 year later. Dissolved reactive P (DRP) concentrations measured in flow water before (0.15-0.20 mg l(-1)) and after (0.39-0.51 mg l(-1)) manure application exceed current estimates of those required to promote surface water eutrophication (0.05 mg l(-1)). Concentrations of DRP1 year after manurial application increased compared to 3 weeks after application and was attributed to the slow movement of P down the cultivated soil. Concentrations of soil P were significantly increased down the soil profile and attributed to the P saturation of soils before manurial application. The results suggest that despite the establishment of fast growing grass, P concentrations would not be mitigated in the short-term (= 1 year), due to the large contribution of P in subsurface pathways.
McDowell
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RW
USDA-ARS, Pasture Systems and Watershed Management Research Unit, University Park, Pennsylvania 16802-3702, USA. richard.mcdowell@agresearch.co.nz
Sharpley
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AN
D000383:Agriculture; D005068:Eutrophication; D008372:Manure; D010758:Phosphorus / Q000032:analysis*; D006109:Poaceae / Q000737:chemistry / Q000254:growth & development; D012989:Soil Pollutants / Q000032:analysis*; D014018:Tissue Distribution; D014872:Water Movements
D008372:Manure; D012989:Soil Pollutants; D010758:Phosphorus