渝东南农田土壤有机碳空间分布特征及影响因素

为评价区域农田土壤肥力及优化农业生产管理措施,选取渝东南地区黔江区为研究区域,基于重庆市测土配方施肥的615个表层(0~20 cm)土样数据,运用地统计学和地理信息系统(GIS)相结合的方法分析黔江区土壤有机碳(SOC)的空间分布特征及其影响因素。结果表明,研究区土壤表层SOC含量为13.27 g·kg^-1,变异系数为31.44%,具有中等程度的空间变异且空间自相关范围较大。块金效应为45.59%,空间分布受结构性因素和随机性因素的共同影响。研究区SOC分布呈斑块状,总体表现为东高西低。方差分析和回归分析表明,成土母质、土壤类型、土地利用方式及坡度、坡向对SOC的空间分布的影响极显著(P<0.01),土壤质地、海拔高度的影响显著(P<0.05)。随着海拔的增加,土壤中SOC含量也逐渐增加。而随着坡度增加,土壤中SOC含量呈先降低后增加的趋势。本研究结果为渝东南农田SOC管理及农作物合理施肥提供了理论依据。

Spatial Distribution Characteristics and Influence Factors of SoilOrganic Carbon in Farmland in Southeast Chongqing

In order to evaluate soil fertility of regional farmland and optimize management measures of agricultural production, Qianjiang District in Southeastern Chongqing was selected as the study area, on the basis of analytic data of 615 topsoil (0-20 cm) samples’ analytic data collected from the area, using geostatistical methods and geographic information system(GIS) together to analyze the spatial distribution characteristics and its influencing factors of soil organic carbon (SOC). Results show that SOC content in the study area is 13.27 g·kg^-1and has a variation coefficient of 31.44%, with moderate spatial variability and its spatial auto-correlation is larger. The nugget-to-sill ratio value is 45.59%, and both structural factors and random factors influence its spatial distribution. The SOC distribution in the area is plaque-like and the value in the east is higher than that in the west. Variance analysis and regression analysis show that parent materials, soil types, land use types, slope and aspect have significant influences on spatial distribution of the SOC(P<0.01), while soil texture and altitude have notable influences on spatial distribution of the SOC(P<0.05). As the altitude increases, the SOC content in the soil also increases. For the slope increases, the SOC content in the soil has a trend of decreasing first and then increasing. The results of this study provide a theoretical basis for farmland SOC management and rational fertilization of crops in southeastern Chongqing.