盐碱土沙穴种植微咸水滴灌土壤水盐运移分异规律与作物响应

The alkali-saline land improvement and brackish drip irrigation is the major requirements in the drought and salinization irrigation. So, to seek a kind of new technology which not only can improve saline-alkali farmland but also no use membranes to control salt accumulation under brackish water irrigation technology is a new research subject. This project, based on the difference of the matrix suction between different soil texture and capillary effect, carry out water salt migration regularity and crop growth response under sand-filled pit (artificial binary soil structure) plantation in the salt soil. Through the two-dimensional soil bin test, to disclose soil water infiltration, evaporation and the salt accumulation characteristics and crop root system distribution response mechanism under the condition of different irrigation water quality drip irrigation; Through simulating soil column experiment, to carry out the influences of groundwater depth on salt and water movement of sand-filled pit structure soil and the crop root system response mechanism; Using simple lysimeter the influences of different water quality of drip irrigation on evapotranspiration mechanism and crop growth mechanism research of tomato in sand-filled pit plantation. At the same time, To find soil hydraulic parameters estimation model under the sand-filled pit plantation condition. Through the different simulation of model for different drip irrigation water quality to find appropriate sand structure and suitable buried depth of groundwater. Then, the mechanism of water-saving and control salt using brackish drip irrigation and saline-alkali soil improvement with sand-filled pit plantation will be established. This will perfect the brackish water irrigation and sand-filled pit plantation of saline-alkali soil technology. At last, the results will provide for theoretical and technical support of brackish drip irrigation in the saline-alkali soil and membrane pollution control based on sand-filled pit plantation .

盐碱地改良与微咸水滴灌是干旱盐渍化灌区面临的重大需求，寻求一种既达到盐碱地改良又减膜抑盐的微咸水滴灌技术是一个新的课题。本课题利用不同质地土壤之间基质吸力和毛管作用的差异，开展盐碱土沙穴种植下人工二元结构土壤水盐运移规律和作物响应研究。通过二维土槽实验，揭示人工二元结构不同水质滴灌条件下土壤水分入渗、蒸发、盐分集聚特征与作物根系分布响应机制；通过模拟土柱开展地下水潜水蒸发对沙穴种植土壤水盐运移的影响及作物根系响应机制；利用简易蒸渗仪开展番茄沙穴种植不同水质滴灌对蒸发蒸腾影响机理和作物生长机制研究；探求沙穴种植条件下土壤参数估算模型，通过模型模拟寻求不同滴灌水质条件下适宜的沙穴土质结构与适宜地下水埋深，揭示沙穴种植土壤进行盐碱地改良和微咸水滴灌的节水控盐机理，完善微咸水滴灌沙穴种植盐碱地水盐调控机理与技术，为盐渍化灌区微咸水滴灌及薄膜污染控制、盐碱地沙穴种植改良技术的应用提供理论与技术支撑。

为了探明盐碱土沙穴种植微咸水滴灌土壤水盐运移分异规律与作物响应机制，以河套灌区代表性盐渍土壤为研究对象，通过试验与模型模拟相结合的方式研究微咸水滴灌沙穴结构土壤水盐运移机理及作物根系响应机制，进行室内入渗试验以分析微咸水矿化度对土壤入渗特性、水盐空间分布的影响，结合室外蒸渗试验以探讨该灌区不同质地盐渍土壤水热盐迁移规律、加工番茄水分耗散特征、生长发育、产量及品质的影响。研究发现，（1）提高灌水矿化度可显著提高均质土壤湿润体积，湿润锋迁移距离与入渗时间具有显著乘幂关系，符合非线性kostiakov入渗公式。（2）沙土粘粒含量较少，灌水矿化度差异对沙土导水率影响较小，灌水矿化度与垂直方向土壤湿润范围成正比，但3 g/L灌水处理会破坏黏壤土中的团粒结构。（3）微咸水灌溉均质土壤可以有效降低表层0-5 cm深度处土壤含盐量，20 h再分布后仍存在轻微的淋盐效果；沙穴结构经过20 h再分布后对土体湿润面积显著增大，作用范围可达到20 cm以下深度的黏壤土部分，2 g/L和3 g/L处理盐分累积深度可达25-30 cm。（4）灌水通量、灌水浓度以及沙穴规格对土壤水盐运移规律影响显著，在实际应用中推荐灌水矿化度不超过基底土壤的60%，可较好控制沙穴处根区土壤盐分高峰值。. 综上所述，微咸水对沙穴结构土壤水分入渗起到促进作用，3g/L微咸水能够提高沙穴结构下粉壤土及黏壤土异质土壤交界深处含水率且积盐效果不显著，提升脱盐区域范围；沙穴结构可有效改善河套灌区黏壤土种植番茄在根层土壤的水热盐环境，促进番茄生长发育进程，达到增产提质的目的。研究结果对微咸水资源实施灌溉的可实施性及开拓盐渍土资源的发展潜力具有积极意义。