Abstract: A conceptual model of agricultural land use systems was established through analysis of the process and characteristics of input and output of the systems. With the aid of the model, analysis was done of environmental risk sources in the processes of agricultural land use from the aspects of input, land use processes and output of the systems. Methods for identification and assessment of environmental risks of the systems were explored. On such a basis, relevant environmental risk factors at a town or township level were identified one by one and assessed by level. In light of the number of risks each evaluation unit is concerned about, comprehensive risk level of each unit is assessed. Taojiang County of Hunan Province was cited for case study. Environmental risks of sewage irrigation, fertilizers and pesticides application, plastic mulching, straw burning and some other human activities were assessed. Results show that the comprehensive environment risk level in the southern part of the county is higher, because of intensive industrial and mining activities and land use, and the county as a whole displayed a declining trend from south to north in comprehensive environment risk level.

Key words: land use systems, environmental risk, risk assessment, Taojiang County