Effects of Topography and Land Use on Soil Organic Carbon in Hilly Region of Loess Plateau

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National Natural Foundation of China (Nos. 41701603, 41601092), Shaanxi Provincial Technology Innovation Guidance Project (No. 2017CGZH-HJ-06)

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    【Objective】As an important component of agricultural soil a major element for plant growth, soil organic carbon (SOC) plays an important role in the earth ecosystem. Huge amounts of organic carbon are stored in the soil, and even a minor change in soil carbon could significantly change the concentration of CO2 in the atmosphere, which drives global climate change. How SOC is distributed and stored is a very important factor affecting soil quality and SOC fixation.【Method】In this study, soil samples were collected from 5 soil layers in each of the 0~100cm soil profiles distributed in a 150m rectangular grid pattern in fields different in slope position (slope top, upper slope, middle slope, and down slope) and in land use (cultivated land, forest land, grassland, shrubland, terrace) in the Wangmaogou watershed of the Loess Plateau. A total of 1080 soil samples were gathered for analysis of how topographies and land use patterns infuence on content and distribution of SOC via Kriging interpolation.【Result】 Among the slope positions, the upper slopes were the highest, (4.49g•kg-1) and followed by the middle slopes (4.30g•kg-1), the down slopes (3.97 g•kg-1)and slope tops (3.34 g•kg-1) in average SOC content of the 0~100cm soil profiles, while among the land use patterns. the forest land (4.31 g•kg-1) was the highest, and followed by the terraced field (4.25 g•kg-1), grassland (4.12 g•kg-1), shrub land (3.82 g•kg-1) and cultivated land (3.47g•kg-1). Obviously the forest land, terraces, grassland and shrub land was 24.2%, 22.4%, 18.7% and 10.1%, respectively, higher than the cultivated land. SOC in the topsoil was more susceptible to environmental factors, like terracing and some other soil erosion control practices, which can obviously sequestrate SOC in the deep soil layers (>20 cm). Variance component estimation shows that interactions between land use, topography, depth, land use and topography had extremely significant influences on spatial distribution of SOC content (P <0.01). Topography contributed the most to total SOC, reaching 32.50%. And interactions between land use & topography explained 7.4% of the variability of SOC. Spatially, SOC was distributed in patch and increased with depth in the watershed, and turned to be homegeneeous in distribution. 【Conclusion】All the findings in this study may serve as theoretical foundations for water and soil conservation and evaluation of carbon sequestration effects.

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ZHANG Yi, LI Peng, XIAO Lie, ZHAO Binhua, SHI Peng. Effects of Topography and Land Use on Soil Organic Carbon in Hilly Region of Loess Plateau[J]. Acta Pedologica Sinica,2019,56(5):1140-1150.

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  • Received:July 09,2018
  • Revised:May 10,2019
  • Adopted:June 19,2019
  • Online: July 03,2019
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