Development of pore structure and related driving factors following land‐use change by dual‐scale x‐ray tomography

Abstract

AbstractLand‐use conversion has a great impact on soil pore structure. However, the variation of pore structure and the related driving factors following land‐use conversion are still in need of further interpretation. In this study, the pore structure of millimetric intact aggregates as well as centimetric undisturbed soil cores collected from paddy fields (PF) and vegetable fields converted from paddy fields for 5 years (VF‐5), 13 years (VF‐13), and 20 years (VF‐20) was quantified by dual‐scale x‐ray tomography. Results revealed that the pore structure at the aggregate and soil core scales responded differently after the paddy fields were converted to vegetable fields. Imaged porosity and pore connectivity of aggregates increased slightly following land‐use conversion. Those properties increased significantly within soil cores. Compared with the paddy field aggregates, the porosity of elongated pores with larger diameters markedly increased in vegetable field aggregates, suggesting an enhancement in the accessibility of air, water, and nutrients. At the soil core scale, the alteration of pore structure was mainly attributed to the shift of the soil environment, the change of tillage operation, and the plantation of different crops. The shift of rice to vegetable plantation significantly altered the length and tortuosity of the intermediate branch pores. Importantly, the land‐use change created a more drainable pore structure due to the significant increase of pore connectivity at the soil core scale, which is suitable for vegetable plantations. These findings are crucial for evaluating and interpreting the microscale pore structure change following land‐use conversion.