不同矿化度咸水梯次入渗滨海盐土的土壤水盐运移规律及机制

The fresh water shortage is the main constraint for the saline-alkali soil reclamation, and the utilization of the saline water resources in saline area is increasingly draw attentions. Based on the rule of separation of saline water and fresh water during the saline water freezing and melting, the technique of freezing saline water irrigation provide an remarkable effect to the saline soil reclamation. While it is a complexed process during the saline ice melting and infiltration, and the continuous infiltration process of meltwater with different salinity and volume into coastal saline soil is occurred. And it is not clear of the soil water and salt movement and the interaction of saline water with soil properties during continuous infiltration of different saline water into saline soils. Focus on the above problem, the lab soil column model experiments and field experiments will be conducted in this project, and the research contains as follows: 1) The soil water and salt movements and model analysis during continuous infiltration of different saline water. 2) The interaction mechanism of saline water with soil structure, chemical properties during continuous infiltration of different saline water. 3) The effect of irrigation by saline water with different salinity on saline soil improvement. This research has important guiding values for revealing the principle of reclamation saline soil by freezing saline water irrigation and saline soil reclamation by saline water utilization.

淡水资源匮乏制约盐碱地的改良利用，盐碱区丰富的咸水资源的利用日益受到重视。基于咸水结冰融化咸淡水分离原理，研发的冬季咸水结冰灌溉改良盐碱地技术效果明显。但咸水结冰融水入渗是一复杂过程，涉及了不同矿化度和水量的融水梯次入渗滨海盐土，而对于不同咸水梯次入渗下滨海盐土的水盐运移规律及咸水与土壤相互作用机制尚不明确。本项目针对以上问题，拟通过室内土柱模拟试验和田间试验相结合的方法，重点研究：1）不同矿化度咸水梯次入渗滨海盐土下土壤水盐运移过程及模型分析；2）不同矿化度咸水梯次入渗滨海盐土下土壤物理结构、化学性质及相互作用机制；3）不同矿化度咸水灌溉下的改土效应。以上研究对揭示咸水结冰灌溉改良盐碱地原理和咸水利用改土具有重要的指导意义。

淡水资源匮乏制约盐碱地的利用，盐碱区丰富的咸水资源利用日益受到重视。基于咸水结冰融化咸淡水分离原理，研发的冬季咸水结冰灌溉改良盐碱地技术效果明显。但上述咸水结冰融水入渗过程复杂，涉及了不同矿化度和水量的融水在滨海盐土的梯次入渗，本项目针对上述关键过程，开展了室内土柱和田间试验，发现咸水梯次入渗过程中，土壤团聚体的平均质量直径（MDW）显著提高，且初期梯次显著高于其他处理，也是使得上一梯次的咸水能够显著提高下一梯次的入渗率，且主要发生在梯次入渗的初期阶段；咸水梯次入渗和咸水冰融水入渗的土壤水盐剖面分布基本一致，其中咸水矿化度越高，越有利于土壤盐分淋洗，且盐分淋洗过程主要发生在初期；田间采用咸水梯次灌溉能够达到与咸水结冰灌溉相似的土壤盐分淋洗效果，结合地表覆盖能够达到春季土壤盐分的淋洗，春季土壤盐分在4g kg-1以下，实现了油葵正常生长，产量达到100kg/亩以上，多年咸水梯次灌溉后土壤饱和导水率显著提高，土壤容重和SAR显著降低；此外对咸水梯次入渗对苏打碱土的入渗特征和盐分淋洗深度影响最大，其次为滨海盐土，最后为硫酸盐土，上述研究结果探明了不同矿化度咸水梯次入渗对滨海盐土的入渗、淋盐和理化特性的影响机制；明确了咸水梯次灌溉下滨海盐土的理化特性、作物生长和水盐运移的变化规律，为进一步揭示咸水结冰灌溉改良盐碱地原理和咸水利用改土提供了依据。