不同供氮水平对春小麦产量、氮肥利用率及氮平衡的影响

【目的】研究施氮量对春小麦产量、氮肥利用率、土壤中硝态氮累积及氮平衡的影响，旨在了解在宁夏引黄灌区减少施氮量的可行性。【方法】通过田间小区试验，设置0、120、240、360 kg/hm24个施氮量，探讨不同施氮水平对作物和环境的影响。【结果】施用氮肥可显著提高春小麦的籽粒产量、籽粒蛋白质含量及成熟期地上部总吸氮量，但过量施用氮肥对籽粒增产和蛋白质含量提高不显著。氮肥利用率随着施氮量的增加呈现降低趋势，根据差值法计算结果，当施氮量分别为120、240、360 kg/hm2时春小麦的氮肥利用率分别为27.2%、24.3%、18.2%，表明多达81.8%～72.8%的氮肥没有被作物吸收利用。氮平衡计算的结果进一步表明，未被当季小麦利用的肥料主要以无机氮的形式存在于0～150cm土层内，施氮量分别为120、240、360 kg/hm2时氮肥的土壤残留率依次为41.6%、33.1%和29.7%，而相应的表观损失率为31.2%、42.6%、52.1%。【结论】综合考虑春小麦产量、品质和环境安全，本试验条件下，春小麦的合理施氮量应控制在120～240 kg/hm2之间。

Effect of N rates on yield of spring wheat, fertilizer N recovery and N balance

【Objective】A field experiment was carried out to study the effects of N application on yield of spring wheat, fertilizer N recovery and N balance in spring wheat (Ning Chun 4) in high productivity field in Yellow river irrigation area of Ningxia province. 【Method】The experiment design was the randomized complete block with three replications, the area each plot was 32 m2 (8m×4m).Four N rates were employed (0, 120, 240 and 360 kg/hm2). 60% of N fertilizer and total P (P2O5 120 kg/hm2) and K (K2O 90 kg/hm2) was used as basal fertilizer, and 40% of N fertilizer used as top dressing fertilizer during the growth stage of jointing. 【Result】The result showed that N fertilizer expects over application significantly increased grain, protein content and total N uptake of shoot of spring wheat in maturity. The apparent N recovery of all N treatments was ranged from 18.2% to 27.2%, which decreased slightly with increasing of N application rates. The research on N balance showed that in spring wheat season, total N mineralization was 54.6 kg/hm2. The apparent N losses were 37.5, 102.4 and 187.7 N kg/hm2, or 31.2%, 42.6% and 52.1% of applied N in the treatment of N120, N240 and N360. 【Conclusion】The results of residual soil Nmin and apparent N losses showed that the amount of fertilizer N should be controlled within 120～240 kg/hm2 in middle or high fertile soil considering spring wheat yield, high efficient N use and low N losses.