Modified no-till and crop sequence effects on spring wheat production in northern Alberta, Canada

In recent years, crop rotation and no-till farming have become common practices in Alberta and are widely recommended to maintain and/or enhance soil quality for sustained crop production, and improve environmental quality. This study was undertaken to evaluate the effects of canola (Brassica rapa L.) and field pea (Pisum sativum L.) as replacements for summer fallow on wheat (Triticum aestivum L.) production, and to determine the role of tillage (no-till versus modified no-till) on crop production on an Albright silt loam (Mollic Cryoboralf) near Beaverlodge, Alta. Spring wheat was grown for 2 years of the 3-year cropping cycle. Crop sequences studied were: canola–wheat–wheat (CWW), field pea–wheat–wheat (PWW) and fallow–wheat–wheat (FWW). The control was continuous wheat, i.e. wheat–wheat–wheat or monoculture wheat (MW). In modified no-till sweeps attached to the seed drill pushed crop residues aside from the centre 7.5 cm of the seed row. Wheat yield following field pea increased by an average (1997–1999) of 10.5% as compared to monoculture wheat. Our data showed no measurable effect of canola on succeeding wheat yields as compared to monoculture wheat. Wheat yields following fallow were intermediate between the CWW and PWW cropping systems. Residue management through the modified no-till system resulted in a warmer seedbed during spring and improved wheat production in all crop rotations studied, especially the first succeeding wheat. Modified no-till also resulted in higher yields of canola but not pea. Our data indicate that in a 3-year rotation with wheat the preferred break crop would be field pea for the cold semi-arid region of Alberta, Canada.