等温与非等温条件下水盐运动特征的比较

Comparison Analysis on Water and Salt Movement Characteristics under Isothermal and Non-isothermal Conditions

近年来新疆地区覆膜种植技术在大面积推广,其中关于覆膜条件下土壤中的水盐运动机理以及覆膜抑盐的机制等关键性科学问题,还需进一步研究。以新疆盐碱土为对象,基于入渗结束后湿润深度不同的等温再分布与非等温全覆膜蒸发的同步实测资料,对比分析了两者的土壤含水量剖面特征,结果表明,两者水分运动引起的含水量剖面差异基本不大,说明全覆膜对于节水有重要意义;基于水分运动特征,含盐率和盐分浓度差异也基本不大,表明温度势梯度对水盐运动的影响不明显。由于土表全覆膜时由水汽散失产生的水分损失量极小,因此相对于裸土蒸发而言,土壤中的盐分上行受到抑制;土表返盐量小,说明全覆膜对抑制土表积盐有同样重要的意义。在上述研究对比的基础上分析了剖面含盐率和盐分浓度与垂向位置和入渗深度的定量关系。本文的研究揭示了地膜覆盖节水特征和抑制土表积盐机制。

With the widely extension of plastic mulch technique in Xinjiang region, the key problems, such as water and salt movement characteristics in isothermal and non-isothermal condition and the mechanics of plastic mulch technique which can prevent soil slat from moving to surface layer, haven't been probed moredeeply. Based on the experimental data of isothermal redistribution and evaporation with entirely plastic mulch of Xinjiang salinized soil for the same period, after infiltration with different wetting depths, their characteristics of soil water content profiles have been compared, and the results shows a little difference, which showed plastic mulch's significance on water saving; Base on that, the soil salt content and soil salt concentration profile are compared and shows a little difference too, which indicated that temperature gradient had no obvious influence on soil water and salt movement and showed plastic mulch's significance on anti-salinization. Later, the functional relations of soil salt content as well as soil salt concentration with vertical position and infiltration depth were developed. The researches in this paper showed the characteristics and mechanics of plastic mulch which preventing soil salt from moving to soil surface.