Effect of water and nitrogen coupling on soil nitrate movement and nitrogen uptake of muskmelon

Effect of different water and nitrogen input on soil nitrogen balance and movement was studied to provide scientific basis for nitrogen fertilizer application reasonably in muskmelon planting area of irrigated desert oasis. The effects of different irrigation rates (1500, 2100, 2700, 3300 m3/ha) and nitrogen rates (N 0，120, 240, 360 kg/ha) on soil nitrate distribution and accumulation, water and nitrogen uptaked by muskmelon and the yield of melon were studied using a split plot experiment in 2009 and 2010. The results show that after the melon harvest the content of soil nitrate is highest in 0-40 cm soil layer, and has a trend of decreasing first, then increasing, and then decreasing in 0-200 cm soil layer. Under the same irrigation rate, with the increase of N fertilizer rate, the soil NO-3-N contents are increased in 80-120 cm soil layers. The accumulation of soil nitrate is increased with the increase of nitrogen application and decreased with the increase of irrigation rate. There is less than 53% nitrate left in 0-100 cm soil layer when the irrigation rate is exceeded 2700 m3/ha. The yield and nitrogen uptake of melon are increased with the increases of irrigation rate and nitrogen rate except the treatment of W2700N240. The nitrogen recovery efficiency is decreased with the increase of nitrogen rate. The highest nitrogen harvest index is obtained in the treatment of W3300N360 and the highest water use efficiency is obtained in the treatment of W1500N240. The treatment of W2700N240 not only can sustain the yield of melon, but also can balance the nitrogen uptake and movement, and can get higher yield and efficiency for water and nitrogen input in melon planting area in irrigated desert soil.