Abstract: 【Objective】 In order to accurately understand the current status of agricultural non-point source pollution on Tuojiang River Basin and find the main pollution source as well as the key pollutants, the agricultural non-point source pollution emission characteristics of Tuojiang River Basin were analyzed, which would provide a theoretical basis for the prevention or control of river basin pollution. 【Method】The historical data statistical analysis method was adopted to analyze the characteristics of agriculture non-point source pollution for twenty-five counties in 2012. The pollutant emissions were estimated by pollution discharge coefficient method and pollution evaluation and sources analysis were carried out by equivalent pollution load method. 【Result】The absolute discharge amount of chemical oxygen demand (COD), total nitrogen (TN) and total phosphorus (TP) of agriculture non-point pollution in the studied area were 52.56×10⁴, 4.10×10⁴ and 0.55×10⁴ t, respectively, in 2012, it is thus obvious that the COD was more than TN and TP. Characteristics of each stream segment were similar to the watershed. Besides, the absolute discharge pollutant of midstream was the most, while the downstream’s was the least. The upstream’s was next only to the midstream’s. The absolute discharge of the pollutants in Renshou county was the highest in the whole basin. At the same time, the absolute discharge of pollutants in Jianyang, Yanjiang and Anyue was also higher than other counties. And the above four counties are also located in midstream. By using standard load evaluation, it was found that the total equivalent pollution load of whole basin was 79 468.23 m³. The equivalent pollution load of TN was the highest (34 151.65 m³), accounting for 42.98% of total emission standard. TP and COD were relatively less. The equivalent pollution load of TP just accounted for 28.98% and the equivalent pollution load of each section on basin also showed TN > TP, COD. In addition, all the counties’ equivalent emission coefficient also presented TN was the highest. The equivalent pollution load almost all come from livestock breeding (44 898.96 m³), accounting for 56.50% of total emission standard. At the same time, livestock breeding as the main source of pollutant, its equivalent pollution load was 56.50% of the total watersheds’. Rural life source’s total equivalent pollution load followed the livestock breeding, while aquaculture source’s was the least (1 311.91 m³). Each stream segment’s equivalent pollution load in the river mainly came from livestock breeding, too. The midstream had the most equivalent pollution load on the Tuojiang River (56 095.43m³). Meanwhile, the equivalent pollution load from upstream and downstream was 12 817.43 and 10 555.37 m³, respectively. Renshou county’s equivalent pollution load was the highest (11 309.51 m³) among the all the counties, which is located in the midstream. Ziliujing county, located in the downstream instead. Refer to the results of equivalent pollution method, twenty-five counties are divided into four types of pollution area. The areas are respectively livestock breeding-rural life leading area, livestock breeding leading area and livestock breeding heavy polluted leading area and rural life leading area. 【Conclusion】 Based on the results above, it was clear that livestock breeding is the key source and the primary pollutant is TN on Tuojiang River watersheds. Tuojiang River Basin agricultural non-point source pollution was combined by production and life. The most seriousiy polluted region is the midstream of Tuojiang, which needs to be most prevented and controlled.

Key words: agricultural non-point source pollution, sources analysis, equivalent pollution load method, pollution types, Tuojiang River Basin