滴灌条件下干旱区农田水盐运移及调控研究进展与展望

以滴灌为代表的节水灌溉技术在我国干旱区大面积推广应用,提高了水肥利用效率,也改变了农田水盐运移模式。一方面,地下水位下降,土壤水与地下水之间的联系减弱,减少了潜水蒸发带来的盐分,使得土壤盐碱化减轻;另一方面,由于缺乏洗盐水量,导致积累在土壤表层的盐分不能及时淋洗入深层,表层土壤盐碱化加重。本文通过回顾滴灌技术在干旱区的应用和研究,系统分析了滴灌条件下干旱区农田土壤水盐运移特点和盐分累积规律,概括了不同作物的水盐响应特征,总结了不同滴灌条件下的土壤水盐数值模型,归纳了目前常用的土壤水盐调控方法。在此基础上提出了需要进一步研究的问题和方向,包括:进一步揭示滴灌条件下土壤水盐运移及累积特征,科学制定农田水盐调控方案;进一步揭示作物水盐耦合响应动力学机制,科学确定调控阈值;发展具有我国自主知识产权的水盐运移和作物生长耦合模拟软件;构建基于生态格局的农田排水和区域盐分处置模式。

Review on water and salt transport and regulation in drip irrigated fields in arid regions

Drip irrigation, one of advanced water-saving irrigation technologies, has been widely applied in the arid regions of China. It can enhance the efficient use of water and fertilizer and therefore increases crop yield. However, it also changes the distribution and accumulation pattern of salt. On one hand, the phreatic evaporation can be reduced due to dropping down of groundwater table and thus soil salinization is alleviated. On the other hand, few water is applied with irrigation and thus salt tends to accumulate in the surface soil layer due to lack of leaching water. To address this emerging issue of soil salinization, an at-tempt was made in this paper to rigorously review:(1) water and salt migration and especially soil salt ac-cumulation under drip irrigation, (2) features of crop responses to water and salt stress, (3) numerical models of soil water and salt movement, and (4) measures for soil water and salt regulation. Based on the extensive literature review, several research tasks associated with drip irrigation were identified:(1) to fur-ther explore characteristics of water and salt migration and accumulation and to develop sustainable opera-tion schemes for field water and salt management under varied climatic and geologic settings, (2) to ex-plore coupled responses to water and salt stress for different crops and corresponding threshold values for management, (3) to develop the numerical software for coupled water/salt movement and crop growth, and (4) to develop ecological pattern based modes on farmland drainage and regional salinity disposal.