绿洲防护林不同滴灌水量下土壤水盐运移初探

为了探明滴灌滴头流量一致条件下,不同灌水量处理对绿洲防护林地土壤水盐随时间分布的影响,采用30L·株-1·次-1(处理I)、40 L·株-1·次-1(处理Ⅱ)、50 L·株-1·次-1(处理Ⅲ)不同处理对比试验,在塔里木河下游喀拉米吉镇绿洲人工栽培的防护林地进行了野外滴灌监测.结果表明:①处理Ⅰ、Ⅱ、Ⅲ的剖面平均含水量分别达6.68％、8.99％、9.92％,土壤湿润锋运移的水平距离分别为58、62、74 cm,垂直深度分别为40、50、67 cm,表明灌水量决定土壤含水量的高低,灌水量增加有利于水分在水平和垂直方向的渗透.②处理Ⅰ、Ⅱ、Ⅲ的盐分锋值水平方向位置为40、52、63 cm,垂直方向为41、45、55 cm,脱盐率分别为62.2％、67.0％、76.5％,灌水量的增加有利于土壤的脱盐.③随着时间的推移,处理Ⅰ、Ⅱ、Ⅲ土壤0～60 cm主要根系分布层分别在第5天、第11天、第15天土壤贮水亏缺度达到23.91％～59.25％,33.38％～51.75％,39.69％～56.53％,表层积盐同时达到最大.本研究认为防护林地滴灌水量40～50 L·株-1·次-1、滴灌周期以11～15 d比较适宜,可为极端干旱区防护林的合理灌溉和防治土壤次生盐渍化提供科学依据,具有一定的现实意义.

The Effects of Drip Irrigation with Different Quota on the Soil Water & Salt Conditions in Oasis Shelter Forest

In order to analyze the effect of different quantities of drip irrigation on soil moisture and salinity distribution and movement at oasis shelter forest, a field experiment with different irrigation quota of 30 L per plant once (treatment Ⅰ), 40 L per plant once (treatment Ⅱ) and 50 L per plant once (treatmentⅢ) was conducted in the Kalamiji oasis shelter forest at the lower reaches of the Tarim River. The results showed that: (1) The mean soil water content in the treatment Ⅰ, Ⅱ and Ⅲ were 6.68%, 8.99% and 9.92%, respectively, the horizontal movement of the soil wetting front value was 58cm, 62 cm and 74 cm for the treatment Ⅰ, Ⅱ and Ⅲ, while the corresponding value for downward movement was 40 cm, 50 cm and 67 cm, respectively, suggesting that the increased drip irrigation volume could promote the water permeability both horizontaly and verticaly. (2) The horizontal movement of the salt front in the treatment Ⅰ, Ⅱ and Ⅲ reached 40 cm, 52 cm and 63 cm, respectively, and the corresponding downward value was 41 cm, 45 cm and 55 cm, respectively, showing that the increased drip irrigation water quantity could promote soil desalinization. (3) The water deficit in 0-60 cm soil of the treatment Ⅰ, Ⅱ and Ⅲ was 23.91%-59.25%, 33.38%-51.75% and 39.69%-56.53% at day 5, 11 and 15 after drip irrigation, respectively, and the salinization value was maximum simultaneously. We thought that a regime with 40-50 L per plant once and 10-15 d cycle could be the most suitable for drip irrigating the shelterbelt.