施氮量对河西绿洲灌区垄作春小麦土壤水氮动态及吸收利用的影响

Effect of Nitrogen Fertilizer Rate on Soil Water-nitrogen Dynamics and Absorption and Utilization of Ridge Culture Spring Wheat in Hexi Oasis Irrigation District

为给河西绿洲灌区春小麦垄作栽培中的合理施氮提供参考依据，设置0、150、300kg·hm^-2三个施氮水平，研究了施氮量对垄作春小麦土壤水氮动态及吸收利用的影响。结果表明，从垄作春小麦播种到收获，土壤含水量持续降低，各生育时期0-200cm土壤含水量均随施氮量的增加而降低。施氮量越大，土壤硝态氮累积越多，且在垂直方向上施氮300kg·hm^-2时土壤硝态氮累积下界面由60cm土层下移到200cm深处，施150kg·hm^-2时土壤硝态氮累积下界面由60cm土层下移到140cm深处。随施氮量的增加，产量先增后降，施氮300kg·hm^-2时氮肥利用率和氮素残留率分别为21．14％和73．84％，而施氮150kg·hm^-2时分别为25．80％和51．93％，两个施氮处理间氮肥利用率差异不显著（P〉0．05），而氮素残留率差异达到极显著水平（P〈0．01）。可见，适量施氮有利于垄作春小麦生长，而过量施氮不仅会导致小麦减产，而且会使大量氮素残留在土壤中，从而加大硝态氮淋溶及污染地下水的危险性。

In Hexi oasis irrigation district, we studied the soil water nitrogen dynamics and absorption and utilization of ridge culture spring wheat at different nitrogen that soil water content continuously decreased during the growth application rate. The results showed period. With the increasing of nitrogen level, soil water content and NO3-N accumulation amount in 0-200 cm soil depth decreased and increased, respectively. Wheat yield increased at first and then decreased with the increase of N application amount. Accumulated NO3-N in soil went down to the soil layers of 140 cm and 200 cm from 60 cm soil layer under the N levels of 150 and 300 kg ·hm^-2, respectively. Nitrogen use efficiency and N residual ratio were 25.80% and 51. 93% under the N level of 150 kg·hm^-2,and were 21.40//00 and 73. 84% under the N level of 300 kg ·hm^-2. Nitrogen use efficiency and N residual ratio had insignificant and significant differences between the two treatments, respectively. Therefore, suitable nitrogen is benefit for wheat growth, excessive nitrogen applicate make yield decreased and residual increase the risk of undergroud water pollution.