Pore Characteristics of Gelic Leptosol on Qinghai-Tibet Plateau Based on X-Ray Computed Tomography and its Relationship with Soil Moisture

Abstract

Soil moisture is of great concern in many fields such as hydrology, agriculture and geology. Soil pores are crucial channel of soil water flow. Previous studies on soil pores are insufficient, and the interaction mechanism between soil pores and soil moisture is not clear. In order to solve this problem, this paper chooses Gelic Leptosol in the middle of Qinghai- Tibet Plateau as the research object. Soil samples were collected in May and August 2021. The depth is 50 cm. Soil pore parameters were obtained by X‑ray computed tomography and Image J software. Based on the objective characterization of soil pore parameters and local natural conditions, the soil moisture absorption equation proposed by Taylor et al was improved. The equation of soil dehumidification is proposed. The relationship between soil pore parameters and soil moisture absorption capacity and dehumidification capacity was established, and the interaction mechanism between soil pore and soil moisture was obtained. It is found that the pores of Gelic Leptosol gradually decreases from the inside to the outside, and mainly develops to the horizontal direction. The number of small flat independent pores accounted for the majority. The ability of moisture absorption is stronger than that of dehumidification. Soil moisture is concentrated at 20-35 cm. The accuracy of the new formulas is 92.45%. This study makes up for the short plates in the high mountain water tower area and provides a basis for the study of the relationship between soil moisture and soil porosity in the world. The important role of soil pore structure in studying the mechanism of soil-vegetation interaction and evaluating soil water conservation was emphasized.

Keywords: Leptosols, Pore characteristics, Soil moisture, X-ray computed tomography, Moisture absorption ability, Moisture dehumidification ability