活化微咸水膜下滴灌土壤水盐运移与棉花生长特征研究

Slight saline water utilization is one of main approach to solve the problem of water resource shortage. There exist is some salt in slight saline water and soil quality and crop growth will be affected when the slight saline water is used to irrigate farmland. It is one important measure to develop scientific regulation method of soil water and salt in order to safely use slight saline water to irrigate farmland. In the project, the methods of theoretical analysis, experimental study and mathematical model are adopted. Physical and chemical feature of magnetic and ionizated slight saline water will be analyzed and the evaluation indexes of activated slight saline water physical and chemical property will be put forward. The suitable infiltration equation and dynamic estimation method of parameter of soil water and salt transport will be established based on the analysis of effects of activated slight saline water on soil physical and chemical properties and soil water and salt transport. The suitable stress coefficients of water, salt and fertilizer will obtained through analysis of soil water and salt transport and cotton growth properties under the activated slight saline water drip irrigation that the soil surface is covered with plastic film mulch. The controlling salt accumulation role of combined approach of the activated slight saline water irrigation, chemical amelioration and salt controlling method between plastic film mulch will be evaluated. The cotton growth model for activated slight saline water drip irrigation with plastic film mulch will be developed considering the role of chemical amelioration and controlling salt method between the plastic film mulch in order to provide the theory and method for safe using of slight saline water and maintaining soil productivity.

随着淡水资源短缺，微咸水开发利用成为缓减水资源供需矛盾的主要途径之一。由于微咸水中含有盐分，影响土地质量和作物生长。因此，发展科学土壤水盐调控方法是实现微咸水安全利用的重要内容。本研究将采用理论分析、试验研究和数学模型相结合方法，在分析磁化水和去电子微咸水理化特征的基础上，提出活化微咸水理化特征评价指标。通过分析活化微咸水对土壤理化特征和水盐运移特征影响，构建适合活化微咸水入渗数学模型，以及水盐运移动力参数确定方法。通过系统研究活化微咸水膜下滴灌土壤水、盐、肥运移和棉花生长特征，提出适合活化微咸水灌溉的水、盐、肥胁迫系数表达式。将活化微咸水灌溉与化学改良和膜间控盐方法相结合，对控盐效果进行综合评价。在综合分析活化微咸水膜下滴灌土壤水盐分布与棉花生长特征基础上，构建活化微咸水膜下滴灌棉花生长模型和土壤水盐调控综合方法，为微咸水安全利用和保障土地生产力提供理论依据和方法。

发展科学土壤水盐调控方法是实现微咸水安全利用的重要内容。本项目采取室内外试验、理论分析和数学模型相结合的方法，在分析活化微咸水理化特征及其对土壤理化特征和水盐运移的动力特征影响机制的基础上，揭示活化微咸水膜下滴灌对土壤水盐分布、棉花生长和水肥利用效率影响机理，提出活化微咸水理化特性的综合评价指标，阐明活化微咸水膜下滴灌与土壤水盐调控措施耦合效应，构建了活化微咸水膜下滴灌棉花生长综合模型，为微咸水高效利用和发展土壤水盐肥综合调控措施提供理论依据。主要成果如下： .（1）分析了不同活化处理对微咸水表面张力、溶解氧、电导率和pH等理化特征的影响，筛选出了关键影响指标，提出了以表面张力相对减少量作为活化微咸水的理化特性的定量评价指标。.（2）研究了活化微咸水对一维土壤水盐运移及土壤水力参数的影响，结果表明在磁场强度为0.28 T时，吸渗率和饱和导水率均达到最小值，磁场强度为 0.3 T 时磁化水盐分淋洗效果最好；微咸水经过磁化处理后，Brooks-Corey模型形状系数n相对减小，而进气吸力hd相对增大，土壤饱和扩散率Ds与起始扩散的土壤含水率均所增加。.（3）研究了活化微咸水对膜下滴灌土壤水盐肥分布及棉花生长特征的影响，结果表明活化微咸水灌溉能够有效的增强土壤的持水和保水能力，促进棉花根系对水分的吸收，提高棉花出苗率，增强盐分的淋洗能力；活化微咸水灌溉棉花产量提高了5%~10%，水分利用效率提高了10%~15%，去电子微咸水灌溉棉花增产效果最好，3000Gs磁化微咸水灌溉水分利用效率最高；活化微咸水灌水量为320 m3/亩、施氮量为300 kg/hm2时，对应的棉花最高产量为420.95 kg/亩。（4）研究了活化微咸水膜下滴灌与土壤控盐措施的协同效果研究，结果表明磁化微咸水膜下滴灌下石膏施量为0.4kg/m2，PAM施量为1kg/亩能够有效调控棉田水盐环境同时获得最高产量；活化微咸水棉花生长模型能够较好的模拟不同活化微咸水处理下棉花各生长指标随生育时间及有效积温的生长过程。