盐渍化灌域不同尺度土壤可溶性物质源汇转化迁移分异规律与驱动机制

Under varying meteorological conditions，water scarcity and soil salinization will restrict the sustainable development of agriculture. For water-saving and salt controlling, to know how the salts distributed and what the mechanism of the soluble substances migrating are essential with using drip irrigation and subsurface drainage. The purpose of this project is to analyze the interrelations among irrigation and drainage water quantity and quality, change characteristics of soil water and soluble substances, salinity distribution in salt-tolerant crops, groundwater level and quality within a saline area. Stable isotope tracer technique is also to be used to reveal soil salinity circulation path, the sources and proportion of the nutrient of nitrogen, and the driving mechanism of soil soluble substances transportation with different scales. Applying the model to simulate and analyze the change patterns of soil moisture-salt-nutrient under different irrigation and drainage ways, to discover how the salined wasteland affect the farmland on their behaviors of moisture and salts. As a result, a reasonable scheme of irrigation and drainage for salined farmland should be proposed and , and "where is salt going" should be revealed quantitatively as well from crop plant, field to agricultural canal scale, which can also be a scientific basis for the study and monitoring of ecological environment effect caused by water-saving irrigation and drainage , and for preventing soil salinization in irrigation area.

在变动的气象条件下，水源不足和盐碱化问题制约着盐渍化灌区农业的持续发展。在节水控盐的目标下，随着灌区滴灌及暗管排水的普及，盐渍化土壤的水盐时空分布及可溶性物质迁移变化规律的驱动机制尚不清楚。本项目针对这种变化环境下，以盐渍化土壤试验区为研究对象，分析灌排水量及水质、土壤水及可溶性物质的变化特征、耐盐作物的盐分分布，地下水位及水质等相互关系及水盐养分时空变异规律。利用稳定同位素示踪技术探讨不同尺度盐渍化土壤盐分的循环路径，养分氮的来源与比例问题，土壤可溶性物质迁移分异规律的驱动机制。利用模型模拟分析不同灌排模式下盐渍土壤的水盐养分变化规律，探明盐荒地对农田水盐动态及盐分调控的影响，提出合理的盐渍化农田灌排调控方案，定量的从作物植株、田间、农渠尺度揭示土壤的“盐分去向”问题。为灌区实施节水灌排技术引起的生态环境效应研究，监控及预防土壤盐渍化提供一定的科学依据。

本文针对河套灌区五原县不同灌排模式、不同程度盐渍化农田为研究对象，分析土壤水及可溶性物质的变化特征、养分氮的来源与比例问题，利用模型模拟分析不同灌排模式下盐渍土壤的水盐养分变化规律。初步用稳定同位素（δ13C、δ15N）探讨了不同类型盐碱地碳氮自然同位素的分布运移规律。后针对不同程度盐渍化农田，识别影响土壤水盐、氮素分布的主要盐分离子，同时利用氮同位素示踪技术，探讨收获后盐氮交互作用下向日葵对肥料氮的吸收利用，残留和损失特性，并分析残留氮肥的后效影响，最终得出了不同程度盐渍化农田的适宜施氮水平。为探明盐渍化灌区不同灌排模式下土壤盐分及离子迁移及聚集规律，分别对“滴灌+明沟排水”与“黄灌+暗管排水”模式下农田进行土壤水盐监测与灌排水量监测，分析不同灌排模式下农田土壤盐分迁移分布规律，利用均衡分析探讨土壤盐分和盐分离子积盐及脱盐特征，得出了滴灌与明沟排水模式、黄灌与暗管排水模式下土壤水盐运移机理及土壤积盐的主控离子。基于Hudrus-2D模型模拟不同灌排模式下农田土壤水盐及其盐分离子的迁移情况，并利用水盐平衡原理估算不同灌排模式下农田水分与盐分的积累情况，为灌区实施节水灌排技术引起的生态环境效应研究，监控及预防土壤盐渍化提供一定的科学依据。