水肥条件与稻草还田对土壤供氮及水稻产量的影响

通过2年田间裂区试验,研究了不同灌溉和施肥条件下,稻草还田对土壤供氮特征及产量的影响。结果表明：（1）上年晚稻稻草还田提高了来年早稻期间土壤NH4^＋-N浓度;配施氮肥后,新鲜早稻稻草还田也增加了晚稻期间土壤NH4＋-N浓度,但在不施氮肥情况下,淹水灌溉稻草还田处理的土壤NH4^＋-N浓度要低于移走稻草处理,间歇灌溉下稻草还田处理的土壤NH4^＋-N浓度仍高于移走稻草处理。（2）稻草还田能促进水稻中后期植株对氮素的吸收及生物量的累积。（3）稻草还田能增加水稻产量,早稻增产幅度为6.85%,晚稻为8.17%;施用氮肥后稻草的增产效应要显著高于不施氮肥,早、晚稻增产分别为9.18%和5.83%。稻草还田主要通过影响有效穗数来影响产量。水稻生长季节、灌溉模式和施肥条件对稻草还田的增产效应存在交互作用,早稻的最佳处理组合为“连续淹灌＋稻草还田＋配施氮肥”,晚稻的最佳处理组合为“间歇灌溉＋稻草还田＋配施氮肥”。

Effects of rice straw incorporation on soil nitrogen supply and rice yield under different irrigation and fertilizer regimes

Two-years field experiment was conducted to study the effects of rice straw incorporation on soil N supply ability and rice grain yield under different irrigation and fertilizer regimes.The study showed:(1) In early rice,straw incorporation increased soil NH4 -N,no matter whichever irrigation regime or N level was adopted.In later rice,straw incorporation still added soil NH4 -N with N supply,however,with N omission,soil NH4 -N was decreased under flooding irrigation while increased under intermittent irrigation after straw added.(2) Straw incorporation increased plant N uptake and above-ground biomass in the later growth of rice.(3) Straw incorporation increased grain yield.The grain yield was enhanced 6.85% in early rice,8.17% in later rice,9.18% with N supply and 5.83% with N omission.More panicles was the main reason that rice grain yield increased after straw returned.In early rice,it was the treatment"continuous flooding straw incorporation N supply" whose grain yield was the most;while it was the treatment "intermittent irrigation straw incorporation N supply" whose grain yield was the most in later rice.