Abstract: Based on the data of the first national survey of pollution, production, discharge and river pollution load of various agricultural pollutants (COD, TN and TP) wereas calculated using their respective production and discharge coefficients. Comparative analysis was done of the status quos of crop cultivation, livestock and poultry rearing and aquaculture in pollutant discharge. Results show that the three sectors differed sharply in proportion of COD, TN, and TP to the total pollutant discharged. COD and TN accounted for 52% and 45%, respectively, of the total pollutant discharged from crop cultivation; and COD accounted for 91% of the total pollutant discharged from livestock rearing and for 80% of the total pollutant discharged from aquaculture. The three sectors also differed sharply in contribution to the total COD, TN and TP discharges from the agriculture in the region. Aquaculture and livestock and poultry breeding were the main contributors of COD to the total from agriculture, accounting for more than 80%; crop cultivation contributed 60% of the TN discharged from agriculture and aquaculture did nearly 60% of the TP discharged from agriculture. Therefore, to reduce organic pollutants, it is essential to begin with controlling measures in livestock and poultry breeding and aquaculture; to reduce nitrogen-like pollutants, in crop cultivation; and to reduce phosphorus-like pollutants, in aquaculture. The findings may provide some valuable references for reducing agricultural pollution and designing pollution controlling measures.

Key words: crop cultivation, livestock and poultry breeding, aquaculture, agricultural pollution, the Taihu Lake Basin