Review of environmental impact and ecological function of agricultural drainage ditches

The agricultural drainage ditch,a vital component of agriculture hydrological facilities,plays an important role in agricultural production and national food security.As the problems of eutrophication and water quality deterioration are becoming more and more serious,a strong focus on the environmental impact and ecological function of agricultural drainage ditches has been getting attached.An agricultural drainage ditch is not only an most important element of agricultural landscape but also is able to regular the water balance of agricultural ecosystem and to improve the agricultural ecosystem.Nutrient in farmland can be rapidly lost from the farm land to the drainage ditch through the draining process.Nutrient can also be removed from the agricultural ecosystem through the process of plant absorption and denitrification.A portion of nutrient losses to the ditch can be retained through the sedimentation and adsorption processes.Being the ecotone of the agro-ecosystem,rich plant diversities provide habitats and shelter places to animal species,which increases the agro-biodiversity in the system.Effects of different management practices,such as dredging,plant mowing and controlled drainage on environment and ecological function may vary in various aspects.In order to achieve a win-win result among utilizing of agricultural drainage ditches and eco-environmental protection,multi-discipline research on environmental impact and ecological function of agricultural drainage ditches should be strengthened in the future.We should explore new techniques to build ecological drainage ditches,and introduce advanced management for ditch operation.