环境科学
地表径流
壤土
土壤水分
农学
土壤健康
磷
腐蚀
放牧
水文学(农业)
土壤科学
土壤有机质
生态学
生物
化学
有机化学
古生物学
岩土工程
工程类
作者
Murray Hart,P. S. Cornish
出处
期刊:Soil Research
[CSIRO Publishing]
日期:2014-01-01
卷期号:52 (3): 293-293
被引量:3
摘要
Management of phosphorus (P) environmental risk has been hampered by the lack of widely applicable threshold values for the soil properties that determine concentrations of P in runoff. This paper simplified the task of developing threshold values by restricting land-use to pastures and by using a single methodology based on simulated rainfall across 38 field sites (76 plots) that included a range of land-use intensities, and soils that varied widely in lithology and soil properties. An ‘adjusted’ soil-test P was determined from the measured Colwell-P minus the threshold P for agronomic response, which was estimated from P-buffering index (PBI). Concentrations of total P (TP) in runoff rose exponentially with rising ‘adjusted’ soil-test P, although only with pastures with high groundcover (r2 = 0.87), or if plots were protected from erosion with a cover of shade-cloth (r2 = 0.70). Concentrations of TP in runoff were low (<0.5 mg L–1) where adjusted Colwell-P was less than zero, which on this scale is the threshold for agronomic response. Similar results were found for dissolved reactive P (DRP) in runoff, although for plots with soil P below the agronomic threshold, the concentrations of DRP were lower than for TP. We conclude that Colwell-P and soil PBI together provide a widely applicable test for environmental P risk from pastures with good ground cover. The same threshold values may be used for both agronomic and environmental purposes.
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