STUDY ON EFFECT OF IRRIGATION ON SOIL NITRATE LEACHING AND UPTAKE

The effect of irrigation on soil nitrate leaching and uptake was conducted with sandy loam soil in the valley of Wudian River. The main results showed as follows: there is a linear relationship between the amount of irrigation water and corn yield, and between the amount of irrgation water and uptake N by corn crop within the range of 0～4000m 3/hm 2 irrigation water. The NO3--N mainly concentrated in 0～60cm soil layer, the peak of which was at 40cm. The remained NO3--N in 0～80cm soil layer was decreased with the increase of irrigation water, and there is no relationship between the remain NO3--N and amount of irrigation water in 80～320cm soil layer, but the remain NO3--N was increased with the increase of irrgation water in 320～400cm soil layer. The relationship between the remained NO3--N and amount of irrigation water was hyperbola at the different depth of soil profile. The N lost from treatment without irrigation and with 4000m 3/hm2 irrigation was lowest. The leaching loss of NO3--N could be decreased with the increase of large amount of irrigation water in right way, the main reasons of which were analysed and gave out the concept of NO3--N leaching and uptake effect.