Impact of coal mining subsidence on computed tomography (CT)-measured soil macropores of cultivated land in northern China

Qiang Zhang1, Xiaoming Guo1, 2*, and Lin Liu3
Understanding and quantification of the spatial variation and the primary factors that affect soil macropore distribution is helpful to restore soil water and productivity of cultivated land. However, the information of spatial distribution and influencing factors of soil macropores in coal mining subsided areas is still scare. We investigated the soil physicochemical properties and computed tomography (CT)-measured pore parameters at different slope positions and slope aspects (shady slope and sunny slope), and quantified the contribution of influencing factors of soil pore using the model of principal component analysis with multiple linear regression (PCA-MLR). The results showed that pH, electrical conductivity and total P had significant difference between two slope aspects, and the contents of quartz, feldspar, calcite, clay, organic matter and Na ion exhibited significant difference among three slope positions. The number of soil macropores (64.23 ± 50.38), macroporosity (4.09 ± 5.36%), roundness rate (0.85 ± 0.03), and connectivity density (1.04 ± 0.63 cm-3) showed obvious spatial variations in the subsided area. The soil macroporosity on the shady slope was significantly higher than that on the sunny slope. The number of macropores and macroporosity at the top slope position were significantly higher than those at the middle and bottom slope positions. The PCA-MLR model estimated that the factors of soil particle composition and organic matter contributed 43% and 24%, respectively, to the distribution of soil macroporosity. In conclusion, coal mining subsidence had directly and indirectly significant impacts on the spatial distribution of soil macropores. The findings of this study are critical for developing strategies for the conservation of soil water through regulation of soil macropore conditions in mining subsided areas.
Keywords: CT scanning, slope aspect, slope position, soil macropores, subsided areas.
1Henan Polytechnic University, Institute of Resources & Environment, Jiaozuo 454003, China.
2China University of Geosciences, State Key Laboratory of Biogeology and Environmental Geology, Wuhan 430078, China.
3China Geological Survey, Nanjing Center, Nanjing 210016, China.
*Corresponding author (guoxiaoming@hpu.edu.cn).