"滴灌小麦免耕复播青贮玉米"氮素周年高效利用机制研究

North Slope of Tianshan Mountain is a typical area where the heat resource is "superabundant for single cropping, insufficient for double cropping". But with the development and application of drip irrigation and no-till planting technology, the drip irrigated wheat and no-till cultivation system was implemented, hereinafter referred to as "Double Drip Irrigation" Mode. In order to make clear the nitrogen residual of former crop how effect on later crop's growth and yield in drip irrigation of wheat and no-till silage corn "double drip irrigation" cultivation system, this research took 3 factors as treatments, i.e. nitrogen application account, processing time and application proportion, and got the optimal former crop nitrogen fertilization scheme. On this basis, setting nitrogen application amount, processing time and proportion of later crop, silage corn, to observe the nitrogen balance, plant dry matter accumulation and yield components in the system, so as to make certain the later crop nitrogen solution, and then optimize the "double drip irrigation" cultivation system of nitrogen. Combined field experiment with micro area test, soil nitrogen transformation became clear in the optimum nitrogen fertilizer of "double drip irrigation" cultivation system, so as to explore the mechanism of efficient anniversary utilization of nitrogen fertilizer under the precondition of high yield, high efficiency, and maintaining soil fertility to get to increase nitrogen use efficiency, reduce environmental pollution aims. This will be helpful to "double drip irrigation" sustained high-yield cultivation system, efficient utilization of resources, food security guarantee, promoting agriculture and animal husbandry combination, and also provide the theoretical support for the local agricultural modernization.

天山北坡属典型"一熟有余、两熟不足"地区，滴灌技术配合免耕播种技术的开发应用，实现了滴灌小麦免耕复播（简称"双滴"栽培）。本项目通过在前茬设不同施氮量、追肥时间次数和比例3因素处理，后茬青贮玉米不施氮肥，以明确滴灌小麦免耕复播青贮玉米"双滴"栽培体系中前茬氮素残留对后茬作物生长和产量的影响，明确最优前茬氮肥施用方案；在此基础上，对后茬作物青贮玉米设不同施氮量、追肥时间次数和比例处理，观察整个体系氮素平衡、植株干物质积累和产量构成，明确后茬作物补充施氮方案，进而优化"双滴"栽培体系施氮方案；通过大田试验和微区试验结合，明确优化施氮方案下"双滴"栽培体系肥料氮去向、土壤氮的转化，从而探索该体系氮肥周年高效利用的机制，实现在高产、高效、维持地力前提下提高氮素利用率、减少环境污染的目标，这将有助于"双滴"栽培体系的持续高产、资源高效利用、保障粮食安全、促进农牧结合,为当地农业现代化提供理论支撑。

新疆地域辽阔，光、热、土地资源丰富，是全国粮食战略后备基地，也是全国4大奶源带之一。新疆天山北坡在小麦收获后有90-105天作物生长期和相应光热资源，麦后免耕滴灌复播青贮玉米是解决粮饲争地、突破农牧结合瓶颈、实现新疆农业现代化的有效途径。但在生产实践中，复播青贮玉米施肥仍参照春播玉米，现有研究则主要侧重从产量和作物生物性状、生理指标来看肥料配比效果，从免耕复播氮素的周年高产、高效、维持地力的机理角度探索仍有待深入。.本项目通过前茬滴灌小麦设不同施氮量、施氮频次和比例处理，根据春小麦生长、叶面积指数、干物质积累、产量和产量构成因素等方面，明确了最优前茬氮肥施用方案为360 kg•hm-2。在此基础上，对后茬作物青贮玉米设不同施氮量、施氮频次、比例，观察整个体系氮素平衡、土壤氨态氮、硝态氮时空分布、植株氮素积累与分配，明确后茬作物补充施氮方案为337.5 kg•hm-2。通过大田试验和微区试验相结合的手段，明确优化施氮方案下复播体系适当增加施氮量可促进小麦植株各器官及全株对氮素的吸收和积累，周年优化施氮方案主要通过提高叶、穗全氮含量、减少气态损失来提高土壤氮素和肥料氮素的利用率，促进作物生长和产量提高。但通过高通量测序探索发现，前茬施肥处理微生物多样性均低于未施肥处理；施肥处理的微生物多样性随施氮量增加而上升，差异性均不显著，脲酶活性未施肥处理低于施肥处理，随前茬施氮量的增加而上升，差异均不显著。有待进一步探索。.本项目研究结果的利用将有利于减少氮肥施用量，实现在高产、高效、维持地力的前提下提高氮素利用率、减少环境污染，有助于滴灌春小麦-青贮玉米种植模式获得持续稳定高产和资源的高效利用，为当地农业持续高效发展提供理论与技术支持，同时，对保障地区粮食安全和新疆稳定、提高农民收入、改善民生等方面做出贡献，对实现农业产业结构调整，促进畜牧业和第三产业发展，推动农业现代化进程也有帮助。