How Intra-Aggregate Soil Pores Under Different Soil Managements Are Influenced by Wetting and Drying Cycles

Wetting and drying cycles (WDC) are one phenomenon that affects soil pore architecture. This study analyzed changes in the pore architecture of subtropical soil under no-tillage (NT), conventional tillage (CT), and forest (F) after WDC application. Three-dimensional X-ray microtomography images of soil aggregate samples (2-4 mm) subjected to 0 and 12 WDC were analyzed. The results showed that WDC did not affect (p>0.05) the imaged porosity, number of pores, fractal dimension, tortuosity, and pore connectivity for the dif-ferent soil management types. To analyze the permeability and hydraulic conductivity of the soil pore system, the most voluminous pore (MVP) was examined. No differences were observed in the imaged porosity, fraction of aggregate occupied by the MVP, connectivity, tortuosity, hydraulic radius, permeability, and hydraulic conductivity between 0 and 12 WDC for the MVP. Comparing soil management types after 12 WDCs, for example, F samples became more porous than CT and NT samples. In contrast, the pore system of NT samples became less complex and more tortuous than CT and F samples. Although the porous architecture, at the intra-aggregate pore scale, proved structurally stable some in-sightful trends suggest that CT may be associated with a less efficient transport of fluids and physical quality.