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The enrichment of soil phosphorus in runoff sediments

Sharpley, A.N.
Journal of environmental quality 1980 v.9 no.3 pp. 521
runoff, soil nutrients, phosphorus, sediments, water pollution, rainfall simulation, soil physical properties, soil chemical properties, slope, rain intensity, linear models, sandy loam soils, clay soils, kinetics, overland flow, prediction, soil erosion
The effect of varying soil physical and chemical properties, soil slope, rainfall intensity, and source on the enrichment of soil P in runoff was evaluated under simulated rainfall conditions. The enrichment of P in runoff increased with increased P additions. The P enrichment ratio (ER) of Bernow soil increased from 2.43 to 6.29 at P additions of 0 and 100 kg P/ha, respectively. As rainfall intensity and soil slope were increased, ER decreased correspondingly. A significant linear relationship between in (ER) and in (sediment discharge) was obtained for all treatments studied. Similar slopes were obtained for soils ranging in texture from a fine sandy loam (-0.233, Bernow soil) to a clay (-0.264 and -0.252 for Houston and Pullman soils, respectively) under similar experimental conditions. In addition, the slopes were not affected by soil P status as slopes of -0.233 and -0.276 at 0 and 100 kg P/ha additions, respectively, were obtained for Bernow soil. With an increase in energy of runoff and kinetic energy of rainfall, a significant increase in slope of the relationship between In (ER) and in (sediment discharge) was obtained. In contrast, a decrease in energy of rain as in the case of overland flow and increased soil cover, resulted in a significant decrease in slope. The data indicated that runoff and rainfall energy and soil P status have a greater effect on ER than soil physical properties. A general relationship between ER and sediment discharge covering all treatments studied predicted ER values very similar to those measured in field studies and those predicted by a general relationship derived from field studies.