Effect of tillage on selected soil biochemical characteristics in a coarse- and medium-textured soil in southwestern Saskatchewan
Characterization of soil organic matter is valuable for identifying the overall quality of soils. Crop management will influence soil quality. Some changes may become apparent more quickly than others and may depend upon soil texture and environmental conditions under which production is conducted. We assessed the impact of tillage [no-tillage (NT) vs conventional mechanical tillage (CT)] and fallow frequency [continuous wheat (Triticum aestivum L.)(Cont W)vs fallow- wheat (FW)] on selected soil quality attributes on a Hatton fine sandy loam soil at Cantuar and a silt loam soil at Swift Current, in semiarid southwestern Saskatchewan. Measurements made in the 0-7.5 cm depth at 4-year intervals after the study was initiated are discussed. In the coarse-textured soil, significant treatment effects on total organic C and N were only observed after 11-12 years. In the coarse-textured soil, labile organic constituents, such as C and N mineralization (Cmin and Nmin showed treatment effects in 7 years, but microbial biomass-C (MB-C) and specific respiratory activity (SRA) (ratio &&B-C) only showed significant effects after 11 years. In the medium-textured soil, total organic C and N and MB-C were not significantly affected by treatment even after 12 years, and Cmin and SRA were only significantly affected after 12 years; Nmin was affected after 8 years. In the coarse-textured soil, soil quality attributes were generally greater in no-tillage (NT) systems than in conventional mechanical tillage (CT) or minimum tillage (MT), and greater in Cont W than in F-W systems. However, in the medium-textured soil, tillage did not influence the soil quality attributes, but cropping more frequently resulted in higher Cmin, Nmin, and SRA. In both soils the response of the labile soil attributes was generally a function of crop residues returned to the land. Of the soil quality attributes tested, Cmin and Nmin were the most sensitive to the agronomic treatments. More research is required to determine why changes in soil quality become apparent more quickly in the coarser-textured soil.
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