水肥条件与稻草还田对土壤供氮及水稻产量的影响

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

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"。

Twoyears 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 aboveground 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.