Phosphorus export by runoff from agricultural field plots with different crop cover in Lake Taihu watershed

Article type: Research Article

Authors: Yan, Wei-jin | Huang, Man-xiang | Zhang, Shen | Tang, Yi-jian

Affiliations: Department of Environmental Biogeochemistry, Institute of Geographic Science and Natural Resources Research, Chinese Academy of Sciences, Beijing 100101, China. E-mail: weijin-yan@263.net

Abstract: Runoff and soil losses from agricultural fields are investigated as major nonpoint sources of phosphorus (P) entering lakes of Eastern China. There is relatively little information on P transport from ricefield and cropland of Lake Taihu watershed in Eastern China. Soil and P in surface runoff from a series of plots in the watershed were evaluated under simulated rainfall conditions. The objectives of this study were to evaluate theeffects of crop cover, slope, and fertilizer application on P concentrations in surface runoff and eroded soil. Accumulated sediment yields varied from 7.1 to 300 g/m² for croplands, depending on management practices. For all experiment plots, weighted average concentrations of total-P (TP), dissolved P (DP) and particulate P (PP) are much higher than 0.02 mg/L, the limiting concentration in lake water. This result showed the potential contamination of lake water from agricultural surface runoff. Accumulated TP losses were 3.8 and 18.8 mg/m² for ricefield and cropland, respectively. The estimated annual loss of TP was 0.74 kg/(hm² · a) for cropland. Most of P loss is in PP form, which accounts for more than 90% of TP loss for cropland.

Keywords: cropland, phosphorus, ricefield, sediment, surface runoff, Lake Taihu

Journal: Journal of Environmental Sciences, vol. 13, no. 4, pp. 502-507, 2001