石膏改良苏打碱土.Ⅰ.经济改良层石膏用量的确定

Gypsum application in amelioration of soda-alkaline soil.Ⅰ.Determination of economical application amount

石膏可以改良盐碱土,室内土柱淋洗试验是验证其改良效果的方法之一。本文将石膏计划改良层定为40cm,计算的定量石膏与0～10cm土层混匀后,装填0～40cm土柱于室内进行分次淋洗试验,将收集的滤液测定溶液离子组成并换算成盐分,应用推理计算法分析石膏溶解、转化、渗漏情况,以及石膏与碱性盐及交换性钠镁作用量。结果表明:将石膏与表层0～10cm土层混匀条件下,4次灌水后,0～40cm的土层物理通透性改善,渗透时间变小,pH由9.25降到8.20,碱化度均基本达到10,而且还有残余石膏,应用推理计算法得出,最经济纯石膏理论改良用量为0.05t·hm-2。

Applying gypsum can ameliorate saline-alkali soil,and soil column leaching experiment is one of the methods to verify the amelioration effect.In this study,the ameliorating soil layer was defined as 0-40 cm,and an indoor soil column leaching experiment was conducted.The 0-10 cm soil layer was thoroughly mixed with the calculated amounts of gypsum,and the filtrate was collected to determine the ionic composition which was then converted into salt.Reasoning calculation method was adopted to calculate the amounts of applied gypsum in the processes of dissolution,transformation,and leakage as well as the amounts of the applied gypsum acted with alkaline salts and exchangeable sodium and magnesium.The results showed that after four times of leaching,the physical and chemical conditions of the soil column improved remarkably,infiltration time reduced,soil pH value decreased from 9.25 to 8.20,and soil exchangeable sodium percentage basically reached to 10.There still had some gypsum left.Theoretically,the most economical application amount of gypsum for the amelioration of soda-alkaline soil was 0.05 t·hm-2.