Capacity and intensity soil aeration properties affected by granulometry, moisture, and structure in no-tillage soils

- Soil pore system functioning and airflow are affected by soil deformation.
- We studied soil air permeability in Oxisols and Ultisol managed under no-tillage.
- Soil compaction reduced primarily air-filled porosity and pore continuity.
- Increased soil wetness, degree-of-compactness, and clay decrease air permeability.
- Soil intensity properties are best descriptors of time-variable soil aeration status.

Soil surface is the locus of complex apportioning of mass and energy reaching the Earth. Pore system functioning of the surface soil, particularly airflow within the soil matrix, is affected by soil deformation. Our objective was to evaluate the effect of soil structure, moisture, and granulometry on soil aeration properties of three Oxisols and one Ultisol managed under no-tillage. Undisturbed samples (572), collected from loose (0.00-0.075 m) and compact (0.075-0.15 m) soil layers, were capillary saturated for 24 h and equilibrated to nine water tensions, from 1 to 500 kPa, to determine capacity (bulk density, volumetric moisture, air-filled porosity, and degree-of-compactness) and intensity (air conductivity and permeability, blocked porosity, and pore continuity) soil physical properties related to aeration; whereas disturbed soil samples were used for soil granulometry analysis. Soil granulometry, moisture, and structure (soil compaction) affect aeration capacity and intensity properties. Regardless of soil wetness, soil compaction reduces air-filled porosity, pore continuity, and air permeability. As soil moisture decreases, air permeability increases because of greater amount and continuity of soil pores available for air flow, and this increase in permeability is greatest in sandy-textured soil compared with clay-textured soils. Intensity properties are better descriptors of the time-variable aeration status of long-term no-tilled soils.