咸水灌溉对土壤理化性质和棉花产量的影响

Effects of saline water irrigation on cotton yield and soil physicochemical properties

水资源短缺是制约区域经济和社会发展的瓶颈,微咸水膜下滴灌是缓解农业用水短缺的有效途径之一。本文通过微咸水和咸水膜下滴灌棉花测坑试验,运用舒卡列夫分类和Piper三线图等方法研究矿化度分别为1、3、6、9、12 g/L水膜下滴灌对土壤含水率、土壤电导率(EC)、土壤八大离子、土壤溶液水化学特征、土壤pH和产量的影响,从而确定棉花适宜的灌水矿化度。结果表明:(1)当矿化度低于6 g/L时,土壤积累的盐分对棉花吸收水分没有严重影响,棉花生理生长适宜的土壤含水率应在10%~20%之间;(2)在不同矿化度水灌溉条件下,0~20 cm土壤处于积盐状态,20~100 cm土层积盐较小,且各处理0~20 cm土壤中SO4^2-、Ca^2+、K^++Na+和Cl^-含量较多;(3)随着灌水矿化度的增大,土壤中的阳离子由Ca^2+逐渐向Mg^2+和K^+变化,阴离子由SO4^2-和HCO3^-逐渐向Cl^-变化,水化学类型由SO4^2-·HCO3^--Ca^2+·K^+型逐渐向SO4^2-·Cl^--Ca^2+·K^+型演化;(4)棉花在蕾期、花铃期和吐絮期土壤pH值随矿化度的增大而增大;棉花产量随灌水矿化度的增加而减小,其中1、3、6 g/L处理下的棉花产量较高。综合各种因素后0~6 g/L是微咸水灌溉棉花适宜的矿化度。

The shortage of water resources is the bottleneck restricting the development of regional economy and society.Drip irrigation with brackish water under film is one of the effective ways to alleviate the shortage of agricultural water.Through the cotton pit test of drip irrigation under brackish water and saline water film,the effects of drip irrigation under water film with salinity of 1,3,6,9,12 g/L on soil moisture content,soil conductivity(EC),eight major ions of soil,water chemical characteristics of soil solution,soil pH,and yield were studied by means of mathematical statistics,Shukalev classification and three-line Piper diagram.Therefore,the suitable irrigation salinity of cotton can be determined.The results show that:(1)When salinity is less than 6 g/L,the accumulated salt in soil will not have a serious impact on water absorption of cotton.Soil moisture content suitable for physiological growth of cotton should be between 10%and 20%.(2)Under different salinity water irrigation conditions,0~20 cm soil is in the state of salt accumulation,while 20~100 cm soil is in the state of less salt accumulation.The contents of SO4^2-,Ca^2+,K^++Na^+and Cl^-in 0^20 cm soil of each treatment were higher.(3)With the increase of irrigation salinity,the cations in soil gradually change from Ca^2+ to Mg^2+ and K^+ and the anions gradually change from SO4^2- and HCO3^- to Cl^-and the hydrochemical types gradually change from SO4^2-·HCO3^--Ca^2+·K^+ to SO4^2-·Cl^--Ca^2+·K^+.(4)The soil pH value of cotton increased with the increase of salinity in bud stage,boll stage and boll opening stage.The yield of cotton decreased with the increase of irrigation salinity.The yield of cotton was higher under 1,3,6 g/L treatments.The optimum salinity water for cotton irrigation with brackish water is 0~6 g/L.