Zero-tillage influence on canola, field pea and wheat in a dry subhumid region: Agronomic and physiological responses

Abstract

Field trials were conducted over 4 site-years in southern Manitoba to compare the response of Katepwa wheat, Westar canola and Victoria field pea to zero tillage (ZT). The experimental design was a split plot with tillage system as the mainplot (ZT vs. conventional tillage (CT)) and crop species as the subplot. All crops received protection from insect, weed and disease pests. Tillage system had only a limited impact on crop dry matter accumulation or grain quality. Where differences were observed, crop performance was enhanced under ZT. Seasonal evapotranspiration (ET) was either reduced or unaffected by ZT, while ET efficiency (ETE: kg ha−1 mm−1 ET) was either increased or unchanged by the shift from CT to ZT. Higher ETE under ZT was attributed to less soil water evaporation. Significant tillage system × crop species (T × S) interactions for growth parameters, ET and ETE indicated that field pea often benefitted more than wheat or canola from ZT. A significant T × S interaction at one of the four sites indicated that water extraction between 30 and 90 cm was higher for pea and canola in the ZT compared with CT treatment, while soil water extraction by wheat was reduced under ZT. At a second site, lower ET for all three crops under ZT was attributed to reduced water use between 90 and 130 cm. Despite some effects of ZT on crop growth and water use, no significant tillage, T × S, or site × tillage interactions were observed for grain yield. It was concluded that under the conditions of this study (i.e. precipitation and temperature conditions close to the long-term average), Westar canola, Victoria field pea and Katepwa wheat were, for the most part, equally suited to ZT production. Key words: Soil water extraction, evapotranspiration efficiency, crop quality, grain yield, canopy development