水氮耦合对绿洲灌区土壤硝态氮运移及甜瓜氮素吸收的影响

在地处沙漠绿洲的甜瓜种植区，研究不同水、 氮输入量对土壤氮素平衡和运移的影响，为当地甜瓜生产的水肥管理提供科学依据。通过2009、 2010连续两年田间裂区试验，研究了不同灌水量（1500、 2100、 2700、 3300 m3/hm2，以W1500、 W2100、 W2700和W3300表示）和施氮量（N 0、 120、 240、 360 kg/hm2，以N0、 N120、 N240和N360表示）对土壤硝态氮分布、 累积和甜瓜的水、 氮吸收以及产量的影响。结果表明，甜瓜收获后各处理土壤硝态氮含量在040 cm土层最高， 0200 cm土层呈现先减少后增加再减少的变化趋势，且施氮量越大，硝态氮在80120 cm土层大量累积的趋势越明显。土壤硝态氮累积量随施氮量的增加而增加，随灌水量的增加而减少，灌水量超过2700 m3/hm2 时，仅有不到53%的硝态氮留存在0100 cm土层。甜瓜产量和果实氮素吸收量随灌水量和施氮量的增加而提高，但在W3300N360处理略有下降。氮素回收率随施氮量的增加持续降低，氮收获指数以处理W2700N240最大，水分利用效率以W1500N240处理最大。W2700N240处理能够兼顾甜瓜产量，平衡氮素吸收运移与土壤中硝态氮的留存空间3个方面，是绿洲灌区甜瓜种植的高产高效的水氮输入模式。

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.