栗钙土不同土地利用方式下土壤活性碳酸钙

Active carbonate of chestnut soils in different lands

土壤活性碳酸钙是指土壤中不稳定的、处于自由态、易发生化学反应的那部分碳酸钙。研究用KMnO4滴定法测定了内蒙古栗钙土的活性碳酸钙质量分数,目的是分析土地利用方式对土壤活性碳酸钙的影响。结果表明:201个土壤样品中活性碳酸钙质量分数的均值为20.57g·kg-1,变幅为0.63～135.59g·kg-1;不同土地利用方式下土壤活性碳酸钙质量分数的大小顺序为:退耕地>锡林草地>乌盟草地>耕地;不同土地利用方式下土壤活性碳酸钙质量分数与碳酸钙质量分数均呈现极显著正相关关系;退耕地、乌盟草地、锡林草地的土壤活性碳酸钙质量分数分别与pH以及土壤粘粒质量分数呈现极显著正相关关系,而耕地的则未达到显著性水平,说明土地利用方式影响了土壤中碳酸钙的活性。土壤总碳酸钙质量分数(n=201)、pH(n=198)和粘粒质量分数(n=191)分别可以解释活性碳酸钙73%、13%和27%的变异。碳酸钙活度指数(CAI)包括了碳酸钙质量分数、pH和粘粒质量分数(CAI=pH+0.01wCaCO3+0.11wClay),是基于每个变量对活性碳酸钙的相对影响而构建的,可以解释活性碳酸钙36%的变异(n=191)。

Soil active carbonate i.e.carbonate reactivity is unstable,free,quantity of reactive carbonate.Active carbonate content in chestnut soils of Inner Mongolia was determined by KMnO4 titration methods.The aim of this investigation was to study the effect of land use on active carbonate.These soils were represented by lands （cropland,grass-replanting cropland,Xilin grassland and Wumeng grassland） sampled in Wulanchabu County and Xilin River Basin.The result indicated that the mean content of active carbonate is 20.57 g·kg-1,ranged between 0.63 and 135.59 g·kg-1,with the order of grass-replanting croplandXilin grasslandWumeng grassland cropland.Statistical evaluation of the data revealed a highly significant positive correlation exited between active carbonate content and the carbonate content in different lands.The active carbonate content was significant positive correlated with pH and clay fraction in soils of grass-replanting cropland and grassland,but that of was poorly correlated in soils of cropland.The carbonate content,pH and clay fraction explained 73%,13% and 27% of the variability in the active carbonate content,respectively.A carbonate activity index （CAI） that combined all measurements （CAI=pH＋0.01wCaCO3＋0.11wClay） was developed based on the relative effects of each measure-ment on the active carbonate content and explained 36% of the active carbonate.