Adapting An Organic Rotational No-Till System for the Northern Climate of Western Canada.

In Western Canada, there has been limited research conducted on reduced-tillage grain production systems managed organically. The overall goal of the study was to adapt an organic rotational no-till system to the growing conditions of Southern Manitoba. A 2-year field study was conducted twice in Carman, MB, Canada, on an Orthic Black Chernozem soil. In year 1 (Y1), ten different combinations of various green manures (GM) species were seeded in the spring and rolled using a roller-crimper in mid-summer, at the flowering stage. The GM species tested included barley, hairy vetch, pea, oilseed radish, and sunflower, in pure stand or in mixtures. These rolled mulches were then left on the soil surface over the fall and the winter. In year 2 (Y2), spring wheat was seeded directly into these mulches (no-till). Mulches with hairy vetch (Vicia villosa) showed the most promising results. GM treatments with hairy vetch had the highest mulch biomass in September Y1 (9.1-11.5 t ha^-1), and in the spring Y2 (6.0-7.6 t ha^-1). In late-fall Y1, nitrogen content of mulches with vetch reached high levels (308 kg N ha^-1, on average), and high amount of nitrogen (93-164 kg N ha^-1) were released from these mulches over winter. Consequently, a significant increase in soil NO₃-N (0-90 cm) was observed overwinter in treatments with vetch. Green manure mulches with hairy vetch were effective at reducing weeds biomass by 50% to 90% in the no-till spring wheat, in 2011 and 2012, compared to other mulches. Organic spring wheat no-till planted into these mulches with vetch produced yields comparable to conventional rural municipality averages. In conclusion, the successful adaptation of the organic rotational no-till system to the growing conditions of Southern Manitoba reduced the need for tillage for a period of 1.5 to 2 years.