广西喀斯特地区荒草地垦田的土壤肥力变化

Changes in Soil Fertility After Grassland Reclamation to Farmland in Karst Areas of Guangxi Zhuang Autonomous Region

在广西壮族自治区喀斯特地区,生态移民工程的实施致使荒草地开垦数量大幅度增加,土地的开垦必然会影响土壤的肥力质量。选择广西环江县开垦30a,15a玉米地及荒草地土壤为研究对象,基于空间代替时间的理论,探讨了喀斯特地区荒草地开垦对土壤肥力质量的影响。在利用相关系数确定评价因子权重,隶属度函数因子归一化,土壤质量综合评分法确定土壤肥力质量分值的基础上,运用Markov法对土壤肥力质量动态变化进行了评价。结果表明,荒草地开垦种植玉米后,0—100cm土层的土壤肥力质量均有下降;相比15a玉米地,30a玉米地土壤肥力质量退化程度较低,土壤肥力质量相对较好;土壤肥力质量退化与土壤深度有关,随着深度的增加退化程度减弱;人为活动的干扰使开垦初期土壤肥力质量退化严重,但是随着开垦时间的延长土壤肥力质量有所恢复。

With the implementation of the ecological migration proiect in karst area of Guangxi Zhuang Autonomous Region, a large number of grasslands were reclaimed for cultivated fields in immigration area, and land reclama- tion inevitably affected the the soil fertility. By choosing corn land of 30 years and 15 years and grassland as the research objects, we studied the influence of grassland reclamation on soil fertility based on the theory of space for time. Soil fertility was evaluated on the basis of determining weight of factors by means of the cor- relation coefficient and normalization of factors through membership function. The results showed that after grassland replaced by corn field, the soil fertility declined in 0-100 cm soil layer; The degradation of 30 years corn was less serious than that of 15 years corn, so the soil fertility of 30 years corn was better; The degradation of soil fertility related to soil depth; The degradation was most serious at the beginning of recla- mation because of the interference of human activities, but soil fertility was restored with the extension of cultivation.