Effects of subsoiling tillage on structure, permeability, and crop yields on compacted Solonetzic and Chernozemic dryland soils in Western Canada

Compaction induced by field wheel traffic and dense layers in the subsoil may adversely alter soil structure, impede soil aeration, restrict water infiltration and nutrient uptake, and inhibit plant root development, negatively affecting plant yields. Reclaiming compacted Chernozemic and Solonetzic soils with hardpan B horizons may be possible through subsoiling operations to loosen the soil to depth, e.g. ~0.30 m. The objective of this study was to evaluate the effect of subsoiling on soil physical properties and plant yield in wheel traffic compacted and non-compacted Chernozemic and Solonetzic soils in southern Saskatchewan Canada. Subsoiling increased air permeability in the compacted Chernozemic soil from 4.5x10-7 m sec-1 to 2.9x10-6 m sec-1. In the compacted Solonetzic soil, subsoiling significantly decreased soil cone index to 1579 kPa compared to 2376 kPa in the non-subsoiled treatment. Crop yields (hard red spring wheat, dry peas) in the two years following the treatment were similar among tillage and compaction treatments in the Chernozemic soil. However, subsoiling of the compacted Solonetzic soil resulted in a seed yield increase of canola of ~ 1000 kg ha-1 in the first year of study and no treatment effect in the second year when wheat was grown. Overall, subsoiling of the compacted soils tended to improve soil physical properties, especially in the Solonetzic soils.