渭北旱塬不同施肥与覆盖栽培对冬小麦产量形成及土壤水分利用的影响

 【目的】研究不同施肥和覆盖栽培模式对渭北旱塬旱地冬小麦产量和水分利用的影响。【方法】通过田间试验，研究测土推荐施氮、顶凌追肥、垄覆沟播、秸秆还田覆盖等措施对冬小麦产量、生物量、收获指数、水分利用效率及土壤水分周年变化的影响。【结果】旱地早春追肥使冬小麦增产6%—14%，水分利用效率提高7%—10%，达到12.2—13.6 kg?hm-2?mm-1；“减氮+垄覆沟播”增产达15%—41%，水分利用率提高10%—30%，达到12.2—16.5 kg?hm-2?mm-1。主要原因是，通过测土优化氮肥用量，采用基肥﹕追肥（3﹕1）方式，并与起垄覆膜栽培措施相结合可促进冬小麦利用深层土壤水分，提高冬小麦抽穗开花期植株含水量和成熟期的生物量及收获指数；虽然生育期耗水增加，但水分利用效率也提高。而单纯减少氮肥用量，不利于水分利用效率的提高；夏季垄上覆膜沟内覆盖作物秸秆可提高休闲效率，利于土壤水分恢复，实现土壤水分周年平衡和旱地小麦可持续增产。【结论】优化施氮结合垄覆沟播是黄土高原渭北旱地小麦增产增效的栽培模式。

Effects of Different Fertilization and Mulching Cultivation Methods on Yield and Soil Water Use of Winter Wheat on Weibei Dryland

【Objective】 Research on effects of fertilization and mulching cultivation patterns on yield and water use of winter wheat is recognized to be of great significance in increasing crop yield and water and nutrient efficiency on Weibei dryland.【Method】Field experiments were carried out to study the effects of recommended N fertilization based on soil test, topdressing, ridge-mulching and furrow seeding, and covering soil surface by retention of wheat straw during summer fallow on winter wheat yield, biomass, harvesting index, water use efficiency and annual changes of soil water.【Result】 Results showed that compared to local farmers’ cultivation mode (apply all the fertilizers to soil once before seeding), topdressing of partial N fertilizer (25% of total) in dry-land region increased winter wheat yield by 6%-14% and WUE by 7%-10%, with WUE reaching 12.2 kg?hm-2?mm-1 to 13.6 kg?hm-2?mm-1; ridge-mulching and furrow seeding combined with N reduced topdressing increased winter wheat yield by 15%-41% and WUE by 10%-30%, and the WUE were as high as 12.2 kg?hm-2?mm-1 to 16.5 kg?hm-2?mm-1. Optimizing nitrogen fertilizer application by 1/4 nitrogen fertilizer being topdressed and at the same time using the ridge-mulching and furrow seeding was found to be able to enhance deep soil water usage by winter wheat, increase water content of winter wheat at heading stage and then enhance the biomass and harvesting index at harvest. This method led to a higher soil water consumption over the whole growing season, but the water use efficiency was also increased due to much more increase of grain yield. However, only reducing nitrogen input did not increase the water use efficiency. Nitrogen reduced topdressing combined with ridge-mulching and furrow seeding also increased soil storage of rainfall water during summer fallow and the summer fallow efficiency, by covering furrow soil surface by retention of wheat straw and keeping the ridge mulched plastic film during summer fallow. This method  achieved annual soil water balance and was proved to be able to sustainablely increase winter wheat yield.【Conclusion】Optimizing nitrogen application combined with ridge-mulching and furrow seeding was showed to be the cultivation and fertilization method to increase yield and water use efficiency for winter wheat growing in Weibei dryland area on the Loess Plateau.