Abstract: A field observation on the nitrogen (N) and phosphorus (P) loss from a gley paddy soil (clayey illitic thermic typic Epiaqualf) in the Taihu Lake region during rice growth season showed that under conventional fertilization, the concentration of N and P in soil surface water and runoff was high at the early stage of rice growth, and then decreased quickly. The rainfall following fertilization caused a great decrease of N and P in soil surface water. During the whole growth season, the total runoff loss of N and P reached as high as 38.8 kg N·hm^-2 and 0.95 kg P·hm^-2, mainly through soil surface water. The majority of lost N was in NH₄⁺-N form, and that of lost P was particulate-P.Under no fertilization, the N and P loss was 47% and 60% of that under fertilization, respectively. At the early growth stage of rice, the runoff loss within 2 weeks after fertilization contributed about 50% of the total N loss and about 33% of the total P loss. The N and P loss after rain gave great contribution to the farmland non-point sources pollution. It was suggested that in the Taihu Lake region, fertilization by turns on the paddy soil with higher fertility could mitigate the N and P loss from paddy soil and the pollution risk of water system.

Key words: Metal oxide, Root exudates, Organic pollutant, Surface chemistry