膜下滴灌暗管排水规律及土壤脱盐效果试验研究

Experiments on drainage rule and soil desalination effect under mulched subsurface pipe drainage

为了探索膜下滴灌盐碱地在灌溉过程中暗管排水规律及土壤脱盐效率,设计了一种暗管排水模型试验装置系统来探究灌溉过程中暗管排水规律和排盐效果.试验通过控制灌水时间、灌水量、观测并记录暗管出水时间、排水流量、排水矿化度、土壤盐分剖面等指标,分析灌溉排水过程中暗管排水流速和排水矿化度特征以及各土层土壤脱盐效率.结果表明:经过3次灌水淋洗试验后,暗管排水流速最终趋于1.5~3.5 L/h稳定范围,排水矿化度稳定在20~40 g/L内;0~40 cm土层脱盐率高达85%,0~80 cm土层土壤脱盐率为80.5%,两暗管中间位置处脱盐率最小分别为57.96%,56.73%,69.29%,暗管上方脱盐率最大分别为71.73%,73.34%,84.26%,暗管排盐量占0~80 cm土层总盐分含量的28.9%,其余盐分被淋洗到了80 cm土层以下.

To investigate soil desalination effect and rules of subsurface pipe drainage in a saline-alkali field under drip irrigation mulched during irrigation process,a well-controlled experimental system was designed to simulate the soil desalination process and identify the effect of soil desalination under surface drip irrigation and subsurface pipe drainage conditions.Drainage and soil salinity distribution characteristics were analyzed by controlling irrigation time and quota and recording the water outflow time,drainage duration,drainage flow rate,drainage water mineralization level and soil salinity profile.The results show that the drainage velocity ultimately tends to be in the range of 1.5-3.5 L/h and the salinity of drainage varies in the ranges of 20-40 g/L after three irrigation leaching experiments.The desalination rates are as high as 85%and 80.5%in the 0-40 cm and 0-80 cm soil layers,respectively.The minimum salt rejection rates in the middle of two concealed pipes are 57.96%,56.73%,and 69.29%,respectively,but the maximum salt rejection rates above the pipes are 71.73%,73.34%,and 84.26%.The amount of salt discharged from the concealed pipes accounts for 28.9%of the total salt content in the 0-80 cm soil layer,and the rest of the salt is rinsed below the 80 cm soil layer.