CHARACTERISTICS OF WATER-SOLUBLE PHOSPHORUS (WSP) LOSS BY RUNOFF IN A PURPLE SOIL WATERSHED.

In this paper, ten typical rainfall events were monitored in Xujiawan Watershed from 2012 to 2013, and a comparative study of the characteristics of water-soluble P loss by runoff under natural rainfall was conducted. The results showed that as the flow-rate increased, the concentration of water-soluble P loss by runoff decreased; however, the concentration of water-soluble P lost by runoff increased linearly as the sediment concentration increased during IM-type rainfall events in Xujiawan Watershed. During the initial and final period of runoff yield, the concentration of water-soluble P loss was lower than that of the increase and decrease in flow-rate. In addition, the water-soluble P loss by runoff followed a severe waveform throughout the entire process. Moreover, the correlation between water-soluble P concentration and runoff, sediments were not obvious in the MD-type and PP-type rainfall events. During the erosion in response to two rainfall events within a short period (less than 5 days), the concentrations of soil water-soluble P loss by runoff erosion during the latter rainfall event were lower than that of the former, while the concentrations of soil water-soluble P in the runoff were the highest in the first rainfall event during a flood season. [ABSTRACT FROM AUTHOR]