中文摘要：

通过对水稻种植期内农业源头沟渠中氮、磷的输出进行长期测定,研究了沟渠系统氮、磷的输出特征及其迁移转化规律.结果表明：试验期间,沟渠系统输出的ρ（总氮）最大值为4.00 mg/L,氮输出的主要形态为氨氮和硝氮,ρ（氨氮）和ρ（硝氮）的最大值分别为3.00和1.83 mg/L;磷输出的主要形态为可溶性磷酸盐,ρ（总磷）和ρ（可溶性磷酸盐）的最大值达1.00 mg/L.灌溉一段时间后,氮、磷的输出呈单调递减变化;降雨后,由于流失方式的变化,氮的输出逐渐增加,2-3 d后才有所降低,而可溶性磷酸盐无大的流失.沟渠系统中不同断面对氮、磷的截留转化作用相似.其中,ρ（总磷）单调递减;ρ（总氮）和ρ（氨氮）在灌溉后随时间逐渐降低,降雨后其随时间虽有所增加,但最终趋势是降低的.

英文摘要：

Based on long-term measurement of N and P concentrations in the agricultural headwater ditches during the planting period of rice, the characteristics of N and P export, transportation and transformation in the headwater ditches adjacent to flee field were studied. The results showed that in the experiment time the highest TN export mass concentration was 4.00 mg/L, and ammonium and nitrate were the predominant forms with the highest export mass concentration being 3.00 and 1.83 mg/L, respectively. The soluble phosphate was the predominant form of phosphorus and TP and phosphate mass concentration reached 1.00 mg/L. The export concentration of N and P from the ditches declined with time after irrigation. During rain time, duo to the change of loss pattern, the export concentration of N gradually increased for 2 - 3 d before declined, and the loss of phosphate was at the low level. The N and P concentration at different sections showed similar trend, which explained that the retentions on N and P in the ditches system were stable. In this situation, the TP mass concentration declined with time, while TN and NH3-N concentrations gradually declined with time after irrigation, increased somewhat after rainfall, but had the trend of decline finally.