江西省耕地土壤有机碳空间变异的主控因素研究

准确地获取省域尺度下土壤有机碳空间变异的主控因素对土壤碳调控以及全球环境保护具有重要意义。本文基于江西省2012年测土配方施肥项目采集的16 582个耕地表层(0~20 cm)土壤样点数据,探讨江西省耕地表层土壤有机碳空间变异的主控因素。运用普通克里格法、单因素方差分析与回归分析方法对比地形因子、耕地利用方式、成土母质、土壤类型、灌溉能力和秸秆还田方式对江西省土壤有机碳空间分布的影响。结果表明:(1)江西省土壤有机碳含量在5.22~40.31 g/kg之间,平均值为17.90 g/kg,变异系数为31.01%,呈中等程度的变异性。(2)经半方差分析,土壤有机碳的变程为30.6 km,空间自相关范围较小;块金效应值为12.49%,表明土壤有机碳空间变异受结构性因素影响大于随机性因素。(3)在空间分布上,高值区主要分布在萍乡市、新余市、南昌市、抚州市与景德镇市。(4)回归分析与单因素方差分析结果表明,地形因子、灌溉能力、成土母质、耕地利用方式、土壤类型和秸秆还田方式对土壤有机碳空间变异影响均显著(P0.05),但影响程度不一。秸秆还田方式对土壤有机碳空间变异的独立解释能力最高,为38.9%,是江西耕地表层土壤有机碳空间变异的主控因素。

Study on Main Controlling Factors of Spatial Variability of Farmland SOC in Jiangxi Province

Accurately accessing spatial variability of farmland SOC and its main driving factors at provincial scale has great influence in regulating soil carbon and environmental protection. The spatial variability of farmland SOC of Jiangxi Province and its controlling factors were quantitatively studied based on 16 582 farmland topsoil samples(0-20 cm) collected in 2012 with the methods of ordinary kriging, variance analysis and regression analysis. The results showed that farmland SOC ranged from 5.22 to 40.31 g/kg, with an average of 17.90 g/kg and the coefficient of variation of 31.01%. The range of farmland SOC was 30.6 km, the nuggest/still ratio were 12.49%, indicating the structural factors played a more important role in the spatial variability of SOC than stochastic factors.The high value of SOC are mainly distributed in Pingxiang, Xinyu, Nanchang, Fuzhou and Jingdezhen.Terrain factors, irrigation capacity, parent material, farmland-use type, soil type and straw returning patterns had significant impact on the spatial variability of SOC(P<0.01), but the influence degrees were different, in which straw returning pattern could explain 38.9% of SOC spatial variability and could be regarded as the main controlling factor of spatial variability of farmland SOC in Jiangxi Province.