土壤干燥化背景下黄土丘陵区农田覆盖措施土壤水分特征及评价

Soil cover is an indispensable technology for dryland agriculture to conserve soil water, as water is the core factor of agricultural production in rain-fed farming. Soil desiccation problems caused by excessive evaporation or losses of soil water, seriously restricts effective soil water cycle. The lack of effective cover measures for sustainable development threatens regional ecological and food security..This project base on the locating observation for mulch film, mulch straw and cover crop. using continuous monitoring soil moisture data, the spatial and temporal variation characteristics of soil water under the cover measures, reveal covering measures on soil desiccation response; Based on soil water balance principle, combining with the indices such as weather, crop growth, analysis cover measures under the soil water consumption and supply and its use of depth, under the change mechanism of soil water under cover measures; Through the quantitative evaluation model of soil water deficit, the paper expounds cover measures of soil water deficit condition, adapted to regional coverage measures are discussed. The results of the study has important theoretical and practical significance on loess area and similar areas cover measures of soil water utilization and management, prevention and cure of soil desiccation and cover measures of continuous application.

覆盖措施是旱地农业不可或缺的技术之一，土壤水是旱区农业生产的关键因子，而土壤水不合理利用严重制约着土壤水的良性循环，阻碍农业生产，并威胁区域生态和粮食安全。. 本项目拟以黄土丘陵区露地栽培，地膜全覆盖、秸秆全量覆盖和覆盖作物等栽培措施的定位观测为基础，利用连续监测土壤水分数据，阐明覆盖措施下土壤水分时空变化特征，揭示覆盖措施对土壤干燥化的响应；基于土壤水分平衡原理，结合气象、作物生长等指标，分析覆盖措施下土壤水的消耗与补给及其利用深度，探明覆盖措施下土壤水的变化机理；通过土壤水分亏缺定量评价模型，阐述覆盖措施土壤水分亏缺状况，探讨与区域相适应的覆盖措施。研究结果对黄土区以及类似地区覆盖措施下土壤水的利用和管理、土壤干燥化的防治和覆盖措施的持续应用具有重要的理论和实践意义。

土壤水库是黄土高原旱作农业持续发展的关键因子，土壤深层土壤水分的储存是调节植物生长最重要的资源，地膜覆盖等栽培技术能够显著增加作物生产力，但在干旱背景下覆盖措施对作物生产力的增加是否引起土壤水环境的退化需要进一步研究。本研究建立黄土高原旱地土壤水土资源可持续利用定位试验，阐述了连续地膜覆盖增加了表层土壤水分，生产过程中产生了一定的低湿度土壤层次。阐明了半干旱区连年地膜覆盖不会像林草地产生下伏土壤干化层，揭示了玉米地土壤水分变化主要集中在0-220cm的土壤层次。阐述了连年地膜覆盖能够引起轻微的土壤水分亏缺和干燥化，地膜玉米比地膜小麦更加明显。阐述了光合有效辐射、平均气温、降雨量、风速与土壤日蒸散量具有显著的正相关。阐述了降解膜、一季膜、双季膜对土壤水分及作物产量的影响规律。揭示了地膜覆盖、免耕＋秸秆覆盖、免耕+覆盖作物和休耕等模式显著提高土壤含水率和降雨保蓄率等指标。揭示了免耕+覆盖作物处理显著增加了作物产量，提高了水分利用效率。揭示了免耕+秸秆覆盖和免耕+覆盖作物处理改善了土壤质量。阐述了不同耕作栽培措施土壤团聚体稳定性特征及其与土壤物理和化学性质的关系。设计研发了螺旋式取土器、土壤环境自动监测系统，实现了农田土壤环境的实时监测。提出了原状土样测定多项土壤物理性质的方法和土壤团聚体不同组分用单位体积含量表述的新指标。项目为区域降雨资源的高效利用、农业绿色发展提供了理论依据，总结的农田土壤质量提升等管理技术在区域新推宽幅梯田和农业绿色生产中得到了应用。同时项目采集了大量水分、养分、微生物和作物产量等数据，还未进行系统的分析，后期将会进一步梳理总结凝练成果。