Study on pollution deduction and environmental impact of water-saving irrigation for paddy fields

Abstract

Paddy is one of the most important grain crops in China. Paddy field irrigation takes up the main part of agricultural water use in southern China. Meanwhile, drainage water from paddy fields has been the principal non-point agricultural pollution source. Different irrigation mode needs different quantity of irrigation water, while drains different load of pollutants in different procedures. Comparative tests of water-saving irrigation and the traditional flooding irrigation were carried out in two irrigation test stations in Zhejiang Province, south eastern China, in order to observe and research the differences of drained pollutants and environmental compacts on the surrounding water quality and the soil quality of the paddy fields resulting from the testing paddy fields of different irrigation modes. The research shows that water-saving irrigation not only saves water resources, but also deducts pollutants and friendly to the environment. During the whole growing season, main water pollutants, like total nitrogen, total phosphor and chemical oxygen demands decreased by at least 22%, deducts the water environmental loads obviously. In the water-saving irrigated paddy field, the total quantity of reducing agents decreased by 20%, meanwhile active substances increased obviously, microorganism carbon increased by 14%; microorganism nitrogen increased by 19.5%, there fore the soil quality was improved obviously.