不同灌水频率条件下设施土壤水盐运移特征

Effects of Irrigation Frequency on Water and Salt Movement in Greenhouse Soil

为了寻求防治设施土壤次生盐渍化的最适灌水频率,通过野外调查与室内土柱模拟试验相结合的方法,分析了不同灌水频率条件下设施土壤剖面水分、盐分及主要离子的变化特征。结果表明,各灌水处理土壤剖面水分变化主要集中在0~20 cm深度土壤,30和40 cm深度土壤为土壤水分的"过渡层",提高灌水频率可使上部土壤含水量增高至0.36 cm^3·cm^(-3)。当灌水总量一定时,1次·(5 d)^(-1)处理不利于土壤剖面水分蓄存。1次·(5 d)^(-1)处理对土壤剖面盐分的淋洗效果优于其他处理,但其质量中心深度为23.71 cm,存在返盐风险。就1次·(5 d)^(-1)处理而言,除对Na+淋洗率较低外,其余离子的淋洗率均高于其他处理,其中NO_3^-淋洗率可达65.68%。根据各灌水处理土壤剖面中的水盐分布状况,提出1次·(10 d)^(-1)为此次试验条件下的最适灌水频率。

In order to explore the most suitable irrigation frequency that could prevent secondary salinization of the soil in greenhouse,field investigations and an indoor soil column simulation experiment were carried out and variation of soil moisture,soil salt and some other major ions in soil profile were monitored and analyzed relative to irrigation frequency.Results show that variation of soil water content with irrigation frequency occurred mainly in the 0-20 cm depth soil. The30 and 40 cm depth soil were soil water transition layers. Increased irrigation frequency could increase soil moisture content in the top soil layer up to 0. 36 cm3·cm-3. When the total volume of irrigation water was set,Treatment one time·（ 5d）-1,that is,irrigation conducted once every 5 days,was not conductive to moisture storage in the soil profile,but conducive to salt leaching,and better than any other treatments in this effect. However,in this case the mass center was at23. 71 cm in depth,posing a risk of salt uprising. Treatment one time·（ 5 d）-1was higher than all the other treatments in leaching rate of all the ions,except Na＋,and the leaching rate of NO3-could reach as high as 65. 68%. Based on the data of distribution of water and salt in soil profiles of all the treatments,Treatment one time·（ 10 d）-1or irrigation once every10 days is considered to be the most suitable irrigation frequency under the conditions of this experiment.