填闲种植和施氮量对旱作冬小麦农田土壤水分及作物产量的影响
Effects of cover crop and N fertilization on soil moisture and crop yield in a dryland winter wheat field

田间试验研究了填闲种植和施氮对旱作冬小麦农田土壤水分和作物产量的影响。试验设双因素处理随机区组设计，填闲作物采用黑麦草单播（R）、长武怀豆单播（S）、黑麦草与怀豆混播（SR）以及裸地休闲（NC），氮肥水平设0、60、120 kg·hm-2三个水平。结果表明，与裸地休闲相比，长武怀豆单播和与黑麦草混播夏闲期降水贮存效率分别降低了9.2%和7.7%，小麦播前土壤含水量减少了19 mm和15 mm，进而导致后续小麦产量的显著下降；而黑麦草单播对土壤水分和后续小麦产量没有显著影响；种植小麦前施加氮肥可以提高粮食作物产量、收获指数和千粒重，同时可增加次年填闲作物生物量，但会加速土壤水分消耗、降低降水储存效率。从土壤水分和作物生产角度考虑，旱作冬小麦种植系统休闲期间可以考虑种植黑麦草以增加覆盖，提高肥力，但不建议填闲种植耗水量较高的怀豆等作物。
A field experiment was carried out to study the effects of cover cropping and N fertilization on soil water and crop yield of dryland winter wheat. Five treatments including cover crops (ryegrass, Changwu cowpea, ryegrass mixed with Changwu cowpea, and fallow) and N fertilization (0, 60, 120 kg·hm-2) were included in a randomized complete experimental design. Compared with the fallow plot, multiple cropping of cowpea and ryegrass significantly impacted the precipitation storage efficiency decreased by 9.2% and 7.7%， respectively, soil water content before planting wheat decreased by 19 mm and 15 mm respectively, that resulted in significant decrease in wheat yield. However, ryegrass did not significantly affect the precipitation storage and water content. Application of N fertilizer before planting increased wheat production and also cover crop’s biomass but decreased soil water and precipitation storage efficiency. It is concluded that ryegrass can be used as a cover crop to increase soil coverage and fertility for the monoculture system of winter wheat in the dryland areas.