title: Spatial analysis of soil organic carbon in Zhifanggou catchment of the Loess Plateau.
abstract: Soil organic carbon (SOC) reflects soil quality and plays a critical role in soil protection, food safety, and global climate changes. This study involved grid sampling at different depths (6 layers) between 0 and 100 cm in a catchment. A total of 1282 soil samples were collected from 215 plots over 8.27 km(2). A combination of conventional analytical methods and geostatistical methods were used to analyze the data for spatial variability and soil carbon content patterns. The mean SOC content in the 1282 samples from the study field was 3.08 g · kg(-1). The SOC content of each layer decreased with increasing soil depth by a power function relationship. The SOC content of each layer was moderately variable and followed a lognormal distribution. The semi-variograms of the SOC contents of the six different layers were fit with the following models: exponential, spherical, exponential, Gaussian, exponential, and exponential, respectively. A moderate spatial dependence was observed in the 0-10 and 10-20 cm layers, which resulted from stochastic and structural factors. The spatial distribution of SOC content in the four layers between 20 and 100 cm exhibit were mainly restricted by structural factors. Correlations within each layer were observed between 234 and 562 m. A classical Kriging interpolation was used to directly visualize the spatial distribution of SOC in the catchment. The variability in spatial distribution was related to topography, land use type, and human activity. Finally, the vertical distribution of SOC decreased. Our results suggest that the ordinary Kriging interpolation can directly reveal the spatial distribution of SOC and the sample distance about this study is sufficient for interpolation or plotting. More research is needed, however, to clarify the spatial variability on the bigger scale and better understand the factors controlling spatial variability of soil carbon in the Loess Plateau region.
authors.affiliation: Institute of Soil and Water Conservation, Chinese Academy of Sciences and Ministry of Water Resources, Yangling, PR China ; University of Chinese Academy of Sciences, Beijing, PR China.
authors.forename: Mingming
authors.initials: M
authors.lastname: Li
authors.affiliation: University of Chinese Academy of Sciences, Beijing, PR China ; State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau, Institute of Soil and Water Conservation,Northwest A & F University, Yangling, PR China.
authors.forename: Xingchang
authors.initials: X
authors.lastname: Zhang
authors.affiliation: Institute of Soil and Water Conservation, Chinese Academy of Sciences and Ministry of Water Resources, Yangling, PR China ; University of Chinese Academy of Sciences, Beijing, PR China.
authors.forename: Qing
authors.initials: Q
authors.lastname: Zhen
authors.affiliation: University of Chinese Academy of Sciences, Beijing, PR China ; State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau, Institute of Soil and Water Conservation,Northwest A & F University, Yangling, PR China.
authors.forename: Fengpeng
authors.initials: F
authors.lastname: Han
mesh_terms: D002244:Carbon / Q000032:analysis; D002681:China; D057231:Climate Change; D003247:Conservation of Natural Resources; D059022:Food Safety; D012987:Soil / Q000737:chemistry*
chemical_list: D012987:Soil; D002244:Carbon