Spatial variability of soil organic C and total N in a small catchment of the Loess Plateau, China

Abstract

Data from the Donggou small catchment, located in a typical wind-water erosion crisscross zone on the Loess Plateau of China, illustrate the spatial variability of soil organic carbon (SOC) and total nitrogen (STN) for the 0-0.10 m, 0.10-0.20 m and 0.20-0.40 m soil depths. Statistical analysis revealed that SOC and STN presented moderate spatial variability in the small catchment, and varied with land use. The SOC and STN contents and variations were also influenced by the five land use patterns in a complex manner. Geostatistical analysis showed that Gaussian models were the best fitting descriptors for these SOC and STN data set. The nugget-to-sill ratio ranged from 39.4-56.3% for SOC semivariograms, and 42.6-59.0% for STN semivariograms, indicating moderate spatial dependence at the three soil depths. Regression analysis indicated that land uses, topographic variables, and soil texture accounted for approximately 57.3% of the SOC variability and 70.1% of the STN variability for the 0-0.10 m soil layer. All regression models were reasonable enough to predict SOC and STN in similar loess areas. It was proposed that creating a mosaic pattern to increase spatial variation of areas by land use arrangement would be an effective management strategy to trap soil nutrients to stay in the ecosystem. Our data also suggested that more C input such as manure addition and crop residues return, and alternative cultivation practices such as application of contour cultivation and building terraces for soil erosion control would improve SOC and nutrients on the hilly areas similar to the Loess Plateau of China. © 2009 Taylor & Francis.