| The nitrate-N content and dynamic distribution in soil under different nitrogen fertilizer were monitored through field test.The result indicated that the content and moving depth of nitrate nitrogen increased with the increase of nitrogen fertilizer.During the cotton growth period,the leaching of nitrate nitrogen arrived in 60～90 cm in optimised treatment,whereas in traditional treatment it arrived in 150～180 cm in flowering stage because of superfluous base nitrogen fertilizer along with the irrigation in early flowering stage.That means the primary influence factors of nitrate nitrogen leaching are based on the nitrogen rate and first irrigation.Generally,the N apply rate of optimized treatment is reasonable because optimized treatment insure both the farmer's income and favorable environment. |