Soil physical quality varies among contrasting land uses in Northern Prairie regions

•Soil quality indicators differed across cropland, pasture and native grasslands.•Native grasslands had greater soil quality than pastures and annual croplands.•Soil fractal aggregation and S-index were strong indicators of land use impacts.•Medium-size soil porosity was greater under perennial versus annual vegetation.•An interplay between management and regional gradients impacts soil quality. Conversion of native grassland to other agricultural land uses can alter soil properties such as organic matter, but little is known about how this impacts soil physical quality indicators in the mixedgrass and aspen parkland natural subregions of the Canadian prairies. This study evaluated soil physical properties in three land use systems (native grasslands, introduced pastures and annual croplands) at seven sites across south-central Alberta, Canada. Hydraulic conductivity (K), pore size fractions and S-index were derived from moisture retention curves measured using a HYPROP system. Fractal aggregation was determined from the mass-diameter relationship of soil aggregates (0.25–8cm diameter) using 3D laser scanning. All our results, except for K, showed a consistent trend of soil quality differences in the following ranking: native grassland>introduced pasture>annual cropland. Relative to croplands, introduced pastures led to an increase from 9 to 12% in medium-size pores (as median volume fraction of 9–50μm diameter), whereas this pore fraction in native grassland was 19% (Ps