Environmental assessment of small-scale vegetable farming systems in peri-urban areas of the Yangtze River Delta Region, China

There is growing concern about food safety and environmental contamination in the rapidly expanding peri-urban interface in Asia. Here, we present an integrated study of farming practices and the quality of water, sediments, soils and agricultural products in small-scale vegetable farming systems in two contrasting peri-urban areas with different levels of industrial development in the Yangtze River Delta Region of China. Application of large amounts of cow manure to vegetables in Nanjing, a vegetable-based peri-urban area, had caused an accumulation of N, P, Cu, Zn and available Cd in soil. This resulted in high Cd in some vegetables and high concentrations of N and P in surface water. Because of a shorter history of vegetable production in Wuxi, an industrialized peri-urban area, the accumulation of N and P in soils was less, but high available Cd due to low soil pH associated with application of large amounts of inorganic fertilizers had resulted in high Cd in some vegetables. Heavy metal pollution in the Wuxi area mainly came from atmospheric deposition and discharge of effluent from factories and was higher than in the less industrialized area in Nanjing. Development and dissemination of strategies for more efficient use of fertilizers in vegetable farming could benefit both farm profitability and the environment and should be coupled with treatment of municipal waste before discharge and control of factory emissions. Bringing about change in farming, municipal and industrial practice will require good relationships amongst a number of stakeholders. The uncertain status of immigrant vegetable farmers in Wuxi hampers their interaction with agricultural service providers and local governance structures and effective channels for communication need to be established.