Pore characteristics of mollisol argillic horizon under simulated freeze-thaw cycles

Taking the cropland soil in mollisol region of northeastern China as the test object, we used simulated freeze-thaw combined with computerized tomography (CT) scanning to study the effects of freeze-thaw cycles on pore characteristics of argillic horizon by quantifying and analyzing the number, average area and roundness of pores. The study was aimed to provide scientific evidences for understanding the mechanism of soil erosion in the region. Results showed that freeze-thaw cycles reduced the number and area of pores in both undisturbed soil and remoulded soil to different degrees and their minimum values appeared after three freeze-thaw cycles. Freeze-thaw cycles significantly affected soil pores with the diameter ≥5 mm. Initial water content during freeze-thaw cycles had less effect on the pore characteristics of argillic horizon in remoulded soil compared with undisturbed soil. Responses of pore characteristics to simulated soil freeze-thaw cycles confirm the effects of seasonal freeze-thaw cycles on argillic horizon, which then induce soil erosion and accelerate the development of gully.