벼농사에서 질소유출이 수질에 미치는 영향평가

Abstract

It is important to understand and evaluate the environmental impacts of rice cultivation for developing environmentally-friendly agriculture because rice is main crop in Korea and rice cultivation have both functions of water pollution and purification with environmental and cultivation conditions. This paper presents the evaluation of nitrogen impact by rice cultivation on water system. A simple protocol was proposed to assess the potential amount of nitrogen outflow from paddy field and most of parameters affect on the nitrogen outflow from paddy field such as the amount of fertilizer application, water balance, the quality and quantity of irrigation water, soil properties, nitrogen turnover in the soil and cultivation method were considered. To develop the protocol, coefficients for parameters affected nitrogen turnover and outflow were gotten and summarized by comparison and analysis of all possible references related, and by additional experiments at field and laboratory. And potential amount of nitrogen input and output by water in paddy field were estimated with the protocol at the conditions of the nitrogen contents of irrigation water, amount of fertilizer application, and irrigation methods. Where irrigation water was clean, below 1.0 mg of nitrogen concentration, rice cultivation polluted nearby watershed. At the conditions of 2.0 mg of nitrogen concentration, 110 kg of nitrogen fertilizer application and flooding irrigation, rice cultivation had water pollution function, but it had water purification function with intermittent irrigation. At the conditions of 3.0 mg of nitrogen concentration and 110 kg of nitrogen fertilizer application, rice cultivation had water purification function, but that had water pollution function with 120 kg of nitrogen application. Where irrigation water was polluted over 6.0 mg of nitrogen, it was evaluated that rice cultivation had water purifying effect, even though the amount of nitrogen application was 120 kg .