氮肥调控与地表覆盖对旱地冬小麦氮素吸收 及残留淋失的影响

【目的】针对西北旱区水分缺乏和氮肥施用不合理的问题，探索作物增产与水肥高效的施肥与栽培模式，以指导旱地农业生产。【方法】通过在黄土高原旱地进行的长期田间定位试验，研究早春追肥、氮肥调控、垄覆沟播、播种密度、夏闲期秸秆覆盖等措施对作物产量与氮素利用，以及收获后土壤硝态氮残留，夏闲期残留硝态氮淋溶和土壤氮素矿化的影响。【结果】旱地早春追肥、氮肥调控+早春追肥、氮肥调控+垄覆沟播、氮肥调控+垄覆沟播增密处理小麦产量比农户常规施肥分别提高15.7%、22.2%、38.6%和24.8%，作物氮吸收增加25.0%、32.0%、36.4%和6.4%，氮素收获指数提高3.8%、3.3%、5.7%和6.8%，当季硝态氮残留减少30.9%、20.0%、59.5%和68.2%，夏闲期硝态氮向60 cm以下土层的淋溶减少27.5%、24.6%、42.3%和24.3%。【结论】渭北旱区早春追肥、氮肥调控+早春追肥、氮肥调控+垄覆沟播和氮肥调控+垄覆沟播增密在提高冬小麦产量的同时，促进作物氮的吸收，减少肥料氮的残留，其中氮肥调控+垄覆沟播结合夏闲期秸秆覆盖，在增加土壤保水蓄水的同时，避免硝态氮向深层淋失，效果更好。

Effects of Nitrogen Fertilizer Regulation and Soil Surface Mulching on Nitrogen Use by Winter Wheat and Its Residue and Leaching in Dryland Soil

【Objective】Since water deficiency and unreasonable nitrogen (N) fertilization are the key factors impacting crop production in dryland area of Northwest China, it is of great importance to work on fertilization and cultivation management for increasing crop yield, water and fertilizer efficiency in this area.【Method】Long term field experiments were carried out to study the effects of topdressing at early spring, N fertilizer regulation, ridge-mulching and furrow seeding, seeding density and straw mulching during summer fallow on winter wheat yield, N uptake, residual nitrate-N after crop harvest and its leaching, and soil N mineralization during summer fallow.【Result】Results showed that compared with conventional fertilization, topdressing at early spring, N fertilizer regulation and topdressing at early spring, N fertilizer regulation and ridge mulching with furrow seeding, N fertilizer regulation and ridge mulching with furrow seeding at high seeding density increased winter wheat yield by 15.7%, 22.2%, 38.6% and 22.4%, N uptake by 25.0%, 32.0%, 36.4% and 6.4%, and N harvest index by 3.8%, 3.3%, 5.7% and 6.8%，but decreased residual nitrate-N in current season by 30.9%, 20.0%, 59.5% and 68.2%, and also decreased leaching of nitrate-N to deep soil layers below 60 cm by 27.5%, 24.6%, 42.3% and 24.3% during summer fallow. 【Conclusion】Thus, topdressing at early spring, N fertilizer regulation and topdressing at early spring, N fertilizer regulation and ridge mulching with furrow seeding, N fertilizer regulation and ridge mulching with furrow seeding at high seeding density increased winter wheat yield while promoting plant N uptake and decreasing residual nitrate-N in Weibei arid areas. The practice of N fertilizer regulation and ridge mulching with furrow seeding combined with covering soil surface by straw mulching during summer fallow increased the water storage in summer fallow while preventing nitrate-N leaching to deep soil, thus is recommended in dryland area of Northwest China.