Nitrate Nitrogen Leaching and its Affecting Factors under Main Soil Types of Chongqing

With soil-resin-core equipment, the difference of NO~-_3-N leaching in soil and its correlation with four aspects including the content of NO~-_3-N, the content of available N, rainfall and temperature were studied. The results were shown as follows: The NO~-_3-N leaching in acid purple soil was the highest, while it was lower in yellow soil and alkaline purple soil. Both the content of NO~-_3-N and available N were correlated positively with NO~-_3-N leaching in acid purple soil. The content of NO~-_3-N and available N were not interrelated with the NO~-_3-N leaching in yellow soil and alkaline purple soil. Rainfall and temperature were also primary factors which affected NO~-_3-N leaching. Fertilization rates, fertilization times, rainfall and temperature could result in together groundwater pollution. To control fertilizer rates, to reduce manure application and to avoid fertilizing in heavy rainfall were the effective ways to control nitrate nitrogen leaching.