Tillage Effects on Thermal Conductivity of Two Soils in Northern British Columbia
- R. H. Azooz and
- M. A. Arshad
Tillage management practices may affect crop growth, in part by altering soil thermal properties. Effects of long-term conventional (CT), no tillage (NT), and modified no tillage (NTR: NT with surface residue pushed away from a 7.5-cm zone over the seed rows) systems on soil thermal conductivity (K) and water content (θ) were evaluated on Donnelly silt loam and sandy loam (Typic Cryoboralfs). Measured K (M1) was compared with calculated K using the McInnes equation (M2) and a modified McInnes equation (M3, which included additional soil properties). The K in both soils increased with an increase in soil θ; the differences among the tillage systems decreased as the soil dried. Soil K for the silt loam was 0.81 (θ = 0.13 m3 m−3), 0.83 (θ = 0.14 m3 m−3), and 0.84 W m−1 K−1 (θ = 0.15 m3 m−3) in CT, NTR, and NT, respectively, at 25 d after planting in 1992 (a dry year). It was 1.13 (θ = 0.42 m3 m−3), 1.53 (θ = 0.50 m3 m−3) and 1.55 W m−1 K−1 (θ = 0.57 m3 m−3) in CT, NTR, and NT, respectively, at 47 d after planting in 1993 (a wet year). Soil K for sandy loam was significantly lower than for silt loam. Soil K measured by M1 and calculated by both the M2 and M3 methods were highly correlated. However, the calculated K values were somewhat improved, although not significantly, with the M3. Mean K was lower by 0.133 W m−1 K−1 in M2 and by 0.045 W m−1 K−1 in M3 than in M1 under CT on silt loam. Increased soil water storage under long-term NT produced a greater thermal contact area and, consequently, a significantly greater K under NT and NTR than CT.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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