点源入流测量条件下水质对盐碱土入渗性能的影响

应用土壤入渗性能自动测量装置,采用无压点源入流测量方法,在4种不同水质条件下(蒸馏水;钠吸附比为5(mmol/L)0.5,电导率分别为2.5、5.0、10.0ds/m),研究灌溉水矿化度对盐碱土壤入渗性能的影响规律。结果表明:1)点源入流方法可以避免雨滴打击以及快速湿润土壤所引起的土壤物理结构破坏,完整地测量出灌溉水质单因素下的土壤入渗率。2)提高灌溉水的矿化度可以增加土壤入渗能力,但随着灌溉水矿化度的增加,土壤入渗能力提高的速率逐渐降低。3)入渗初期,最大湿润深度和累积入渗量均随时间呈幂函数增长,随着入渗趋于稳定二者均随时间近似呈直线关系增长,且最大湿润深度和累积入渗量均随着矿化度的提高而增加。4)连续入渗4h后,3种含盐水的累积入渗量均大于蒸馏水,最多约达蒸馏水的2倍。试验结果对盐碱地水盐管理具有指导意义。

A point source method for determining the effect of water quality on soil infiltration capability

An automatic soil infiltrability measurement system was applied to measure infiltration processes in laboratory to study the influences of water quality on saline-alkali soil water infiltration by using point source infiltration method.Distilled water and other three irrigation water qualities of EC=2.5, 5.0, 10.0 ds/m at SAR=5 (mmol/L)^0.5 were adopted in the experiments .Results indicated that the measurement was capable of measuring the complete infiltration process and the method could avoid the soil physical structure damage caused by raindrops hit and fast wetted soil.High salinity of irrigation water was beneficial to soil water infiltration.But the increasing rate of infiltration gradually decreased with the increase of EC.The relationships among infiltration time, maximal vertical wetted distance and accumulated infiltration were a power function at the beginning of infiltration.Both the maximal vertical wetted distance and accumulated infiltration increased with the increasing of salt concentration.After 4 h of irrigation, all the accumulated infiltrations of the three saline water levels were greater than that of the distilled water, which the highest being about 2 times of the distilled water.The research results should be significant to salt management for saline-alkali soil.