黄土高原南部春玉米地膜栽培的水肥效应与氮肥去向

在黄土高原南部采用田间小区和微区试验，研究了春玉米地膜栽培下氮肥-水分-产量关系与氮肥去向。结果表明，相同施肥条件下地膜栽培(N120C)比平作栽培(N120UC)增产显著(46．7％)，施用氮肥显著地发挥了地膜的增产潜力，处理N120(尿素氮120kg·hm^-2)、N180(尿素氮180kg·hm^-2)和N120M(尿素氮120kg·hm^-2+有机肥氮60kg·hm^-2)，籽粒产量比对照CK(不施氮)分别增产41．8％、43．9％和34．7％，地膜栽培或施用氮肥都极大地改善了玉米水分生产效率(WUE)和降水利用率(RUE)，试验中N120C比N120UC水分生产效率提高57．9％。降水利用效率提高54．5％；处理N120、N180和N120M比CK处理WUE分别提高38．4％、47．4％和32．4％，RUE分别提高42．3％、43．9％和34．7％，由于供试有机肥是半腐解的牛粪，比尿素氮素供给迟缓，所以对玉米产量和WUE提高幅度小，试验水分测定反映出，玉米利用的水分73．0％～83．7％来自降雨，表明决定春玉米产量的关键水分是生育期降水，玉米地膜栽培对氮肥去向有微弱影响，相对于平作玉米，氮肥总的回收率差异不大，但氮肥利用率下降7．3个百分点，土壤残留率上升6．4个百分点，土壤当季残留氮主要集中在0～20cm，不会发生向深层大量的淋溶和累积。

Effect of plastic-film mulch on water and nitrogen use by spring maize and on fate of applied nitrogen in the southern Loess Plateau

The relationships between nitrogen and yield and between water and yield, and the fate of nitrogen under plastic film mulching for spring maize were studied with field plots and microplots in the southern Loess Plateau. The results showed that plastic-film mulching (N120C) could increase maize yield by 46.7%, comparing with no-mulching(N120UC) in same rate of fertilizer. The maize yield potentiality of mulching might be played fully, comparing with CK (no nitrogen), treatments N120 (urea nitrogen 120 kg.hm-2), N180 (urea nitrogen 180 kg.hm-2) and N120 M (urea nitrogen 120 kg.hm-2 + organic manure nitrogen 60 kg.hm-2) could raise grain yield by 41.8%, 43.9% and 34.7%, respectively. Mulching planting raised water use efficiency (WUE) by 57.9%, and raised rainfall use efficiency (RUE) by 54.5%. N120, N180 and N120M improved WUE by 38.4%, 47.4% and 32.4%, respectively, and improved RUE by 42.3%, 43.9% and 34.7%, respectively. Because the organic manure applied was not fully rotted cattle dung, which supplied available nitrogen slowly than urea, it raised yield and WUE to a low extent. Meanwhile, the experiment showed that 73.0%-83.7% of water used by maize from rainfall, which indicated that the key water to determine maize yield was rainfall in spring maize growth period. Mulching planting for maize had little impact on the fate of nitrogen fertilizer. The total recovery of nitrogen had little difference, NUE decreased 7.3%, and residual N in soil raised 6.4%, comparing with N120UC. A great part of the residual N was in 0-20 cm of soil, and no risk occurred for nitrogen leaching and accumulation to deeper soil layers in the first growth season.