Tillage Effects on Soil Thermal Properties in a Semiarid Cold Region

Tillage and residue management may sufficiently alter soil thermal properties in cold, semiarid regions, causing significant changes in crop growth. Soil thermal diffusivity ( D b ) and heat flux density ( J s ) were measured in conventional tillage (CT), no‐tillage (NT), and modified no‐tillage where surface residue was pushed away from a 7.5‐cm zone above the planting row (MNT) on a Donnelly silt loam (Typic Cryoboralf) in northern British Columbia during barley ( Hordeum vulgare L.) growing seasons of 1992 and 1993. The D b for 0‐ to 30‐cm depth ranged from 0.00126 to 0.00194 m 2 h ‐1 in NT, 0.00129 to 0.00196 m 2 h ‐1 in MNT, and 0.00133 to 0.00199 m 2 h ‐1 in CT during the two growing seasons. Differences in D b were highly related to soil water content, where soil water in NT ≥ MNT > CT during most of the growing season. Mean diurnal temperature at 5‐cm depth during the first 3 wk after planting in 1992 was 12.4°C in MNT, 11.2°C in NT, and 13.3°C in CT. Mean of maximum soil heat flux at 5‐cm depth was lower by 10.0 W m ‐2 in MNT and by 20.7 W m ‐2 in NT than in CT in 1992 and it was lower by 23.7 W m ‐2 in MNT and by 34.7 W m ‐2 in NT than in CT in 1993. Seed‐row residue removal in MNT increased soil temperature, maintained soil water similar to NT, and led to increased seed‐zone heat flux density.