半干旱区施氮和灌溉条件下覆膜对春玉米产量及氮素平衡的影响

以典型半干旱区干湿砂质新成土（Ust-Sandic Entisols）为供试土壤进行田间试验，研究地膜覆盖、施氮及补充灌水量对春玉米（Zea mays L.）产量、土壤矿质氮（NO3--N和NH4+-N）及氮素平衡的影响。结果表明，0—100 cm土体范围内，随着土层加深，播前和收获后土壤NO3--N含量呈降低趋势，NH4+-N有所增加，但变幅不大；总矿质氮量（NO3--N和NH4+-N）表现为下降。说明地膜覆盖和施氮并没有使NO3--N深层累积量增加，这可能与土壤本身供氮能力严重不足有关。与不施氮相比，施氮各处理氮肥表观损失量增加；与不覆膜相比，作物氮素累积量比不覆膜显著增加（P0.05）。在低灌（80 mm）覆膜和高灌（160 mm）覆膜条件下，玉米的氮肥利用率均比不覆膜均提高了18.8%，说明覆膜低灌在相同施氮条件下，可节约80 mm灌水。但低灌（80 mm）与高灌（160 mm）不覆膜间氮肥利用率差异不显著，表明在相同施氮条件下，覆膜可有效提高氮肥利用率，减少氮素损失。综合考虑籽粒产量和氮肥利用率，“覆膜+补灌80 mm+施氮90 kg/hm2”可能为本试验条件下较优的栽培模式。

Effect of film mulching on yield and nitrogen balance of spring maize under different nitrogen and irrigation treatments in semi-arid region

A field experiment was carried out on typical Ust-Sandiic Entisols soil in semi-arid area to study the effect of film mulching, nitrogen (N) application and supplementary irrigation on spring maize (Zea mays L.) yield, soil mineral N (NO₃^--N and NH₄⁺-N) and N balance. The result showed that in the 0-100 cm soil profile, with the depth of soil layers increasing, NO₃^--N content before sowing and after harvest decreased, NH₄⁺-N increased slowly, and the total mineral N content declined (NO₃^--N and NH₄⁺-N). It indicated that film mulching and N application did not increase NO₃^--N accumulation in deep layer. This might be related to the soil’s insufficient N supplying ability. The N apparent losses increased in all the treatments under N application compared to the zero N application treatment. The crop N accumulation significantly increased (P<0.05) compared to the no film mulching treatment. In the 80 mm and 160 mm irrigation with film mulching treatments, the N fertilizer use efficiency of maize increased 18.8% compared with no film mulching. This indicated that under the same N levels, low irrigation (80 mm) with film mulching could save 80 mm water. However, the difference of N fertilizer use efficiency between 80 mm and 160 mm without film mulching was not significant. This indicated that film mulching increased N fertilizer use efficiency and decreased N losses under the same N application condition. In terms of grain yields and N fertilizer use efficiency, the recommended management practice would be “film mulching + supplementary irrigation at 80mm + N application at 90 kg/ha ” based on results of this experiment.