基于秸秆带状覆盖技术模式的西北内陆灌区春麦田节水机制研究

Due to low rainfalls and high evaporation in the inland irrigation regions in northwestern China, straw mulching still needs to settle the conflict of water saving and moisture conservation with the crop failure caused by temperature reduction when being popularized and applied as an efficient green agronomic water-saving measure in the local place. Regulating the water temperature of the soil partially, the bundled straw mulching technology effectively handles the conflict between water saving and temperature reduction, thus saving water and increasing benefits simultaneously in crop production. Therefore, in this program this technology pattern was introduced in spring wheat fields in the inland irrigation regions in northwestern China. A systematic study was conducted on the spatial and temporal changes and differences in the soil moisture of different soil layers in the mulching belts and the planting belts in different periods and years. Then, the water saving and moisture conservation effects of this technology were revealed. A study was performed on the influences of this technology pattern on soil water storage capacity, evaporation, infiltration moisture storage rate, granular structure, porosity, and other physical soil properties in the mulching belts and the planting belts as well as its relationship with soil moisture. Then the water saving and moisture conservation ecological mechanism of this technology was uncovered. Another study was carried out on the influences of this technology pattern on dry matter accumulation, yield, farmland water consumption, and water utilization efficiency above the ground, and an in-depth discussion was had on the correlation of these indicators with group water utilization and soil water temperature. Then detailed explanation was provided for the mechanism of how spring wheat fields saved water and increased benefits when applying the bundled straw mulching technology. The results of this program will further enrich the theories of mulching oasis irrigation regions for water conservation and benefit increase and also promote the innovations of the local straw mulching agronomic water-saving technology.

西北内陆灌区低降水高蒸发，而秸秆覆盖作为一种绿色高效农艺节水措施，在当地推广应用尚需解决节水保墒与降温导致减产二者间的矛盾。秸秆带状覆盖技术对土壤水温进行局部调控，有效控制了秸秆覆盖节水与降温的矛盾，进而实现作物生产节水增效。因此，本项目在西北内陆灌区春麦田引入该技术模式，系统研究该技术模式下覆盖带与种植带在不同时期与年限以及不同土层的土壤水分时空变化差异，明确该技术模式的节水保墒效果；研究该技术模式对覆盖带与种植带土壤温度、土壤贮水量、蒸发量、团粒结构、孔隙度等土壤物理性状的影响及其与土壤水分的关系，揭示该技术模式节水保墒的生态机制；研究该技术模式对地上部干物质积累、籽粒产量、农田耗水、水分利用效率的影响，深入探讨各指标与水分利用及土壤水温动态的相关关系，阐明秸秆带状覆盖技术模式下春麦田节水增效的机理机制。项目成果将进一步丰富绿洲灌区覆盖节水增效理论，促进当地秸秆覆盖农艺节水技术的创新。

研发能协调秸秆覆盖保墒与降温的矛盾限制的新型秸秆覆盖种植技术，已成为西北内陆灌区发展秸秆覆盖种植这一绿色农艺节水措施亟待解决的问题。秸秆带状覆盖技术对土壤水温进行局部调控，有效控制了秸秆覆盖节水与降温的矛盾，进而实现旱地作物生产节水增效。本项目在西北内陆灌区春麦田引入该技术模式，研究该技术模式下西北内陆灌区春麦田节水增效的机理机制，为西北内陆灌区秸秆覆盖技术的优化和推广提供理论与实践依据。通过4年定位试验得到重要结论如下：.1、西北绿洲灌区，秸秆带状覆盖降低春小麦生物量6.1%，提高收获指数5.4%，保持产量三要素与CK无显著差异，取得与露地条播相当的产量潜力。2、秸秆带状覆盖提高春小麦拔节前土壤温度，降低春小麦拔节后土壤温度。同时，秸秆带状覆盖通过调节土壤热量传导性能，减弱土壤高温点热量传导，加快土壤低温点热量传导，平抑全生育期土壤温度的波动。3、秸秆带状覆盖改善春小麦全生育期土壤墒情，减小棵间蒸发量及棵间蒸发量占耗水比重，显著降低生育期耗水量，最终显著提高水分利用效率2.1%~4.2%。4、秸秆带状覆盖显著改善春小麦植株水分状况，降低生育期植株水分变异。植株水分与土壤水分呈显著正相关，且受90m以下土壤水分影响明显，而与土壤温度呈显著负相关。5、秸秆带状覆盖显著提高了＞0.25mm的大粒径机械稳定性团聚体含量，降低了土壤容重显著，增加了土壤总孔隙度，秸秆带状覆盖改善了与土壤水分保蓄相关的土壤物理性质，提高土壤贮水量。6、秸秆带状覆盖显著降低覆盖带土壤蒸发，提高秸秆覆盖带土壤贮水量，保持较高的土壤水势，最终增大土壤水分从秸秆覆盖带向小麦种植带的潜在运移量，全生育期潜在运移量达74.9~82.0 mm。.总之，秸秆带状覆盖通过改善土壤团粒结构，降低土壤容重，增加土壤孔隙度，优化土壤水温环境，提高覆盖带向种植带的土壤水分转移，降低农田耗水，保证春小麦产量，实现春小麦生产节水增效。秸秆带状覆盖是一种节水增效，利于西北绿洲灌区农业可持续发展的种植方式。