桂林喀斯特地区干湿循环过程中土壤水含量的空间变异

[目的]研究桂林喀斯特地区干湿循环过程中土壤水含量的空间分布变化,为解决该地区农田水土流失及农作物防旱抗旱提供理论依据.[方法]选取种植有大豆、梨树和甘蔗3种不同农作物的耕作地为试验地,分析3种试验地在干湿交替条件下土壤表层0~6 cm土壤水含量的空间变异,并利用地统计方法研究不同土地利用方式下的土壤空间分布变异.[结果]大豆、梨树和甘蔗3种试验地的土壤质地差异不显著(P>0.05),土壤容重表现为梨树地最小,但土壤有机质含量和总孔隙度均以梨树地最高.3种试验地湿润阶段的土壤水含量是干旱阶段土壤水含量的2~3倍.在整个干旱—湿润循环过程中,3种试验地的土壤水含量均表现为梨树地>甘蔗地>大豆地,土壤水含量空间分布比为37.18%~95.99%,呈中等偏上的空间相关性,说明试验地的空间分布在一定范围内表现稳定,但因不同的土地利用方式存在一定变异性,变异强度也因其耕作方式或管理方式的不同而异.[结论]桂林喀斯特地区土壤自身具有维持其土壤水含量空间分布稳定的能力,但耕作方式、灌溉等人为因素在一定程度上会削弱土壤水含量的空间稳定性.

Spatial variation of soil water content under drying and wetting cycle in karst area of Guilin

[Objective] In this study,spatial variation of soil water content under drying and wetting cycle in karst area of Guilin was investigated to provide theoretical reference for solutions to soil and water loss and crop drought resistance in the area.[Method] Three plots cultivated with soybean,pear trees and sugarcane were investigated to analyze the spatial variation of soil water content in upper soil layer(0-6 cm) under alternate drying and wetting conditions,and the variation of soil spatial distribution under different land use patterns was studied by geostatistical method.[Result] The difference in soil texture among the three plots was not significant(P＞0.05).Pear tree plot presented the lowest soil bulk density,but the greatest soil organic matter content and total porosity.The soil water content of these three plots during wet stage was nearly 2-3 times of the soil water content during dry stage.During the whole drying and wetting cycle,soil water contents of the three plots were pear tree plot＞sugarcane plot＞soybean plot.The proportion of spatial distribution of soil water content was 37.18％-95.99％,presenting a medium-high spatial correlation.It referred that the spatial distribution of plots was stable within a certain range.However,as different land use patterns resulted in certain variation,the variation intensity depended on tillage method or management mode.[Conclusion]The soil in karst area of Guilin has the capacity to maintain stability of spatial distribution in soil water content which can be weakened by human factors such as tillage method and irrigation to a certain extent.