Zero-tillage establishment of alfalfa and meadow bromegrass as influenced by previous annual grain crop

Abstract

Conventional forage establishment techniques (i.e. preseeding tillage) can result in soil erosion and inefficient water use during the establishment period, and may result in poor plant establishment. Using a zero-tillage (ZT) system may overcome these limitations. The first experiment, conducted under favourable post-seeding moisture conditions, compared establishment, plant development, growth, and dry matter production of alfalfa (Medicago sativa L.) and meadow bromegrass (Bromus biebersteneii Roem and Shult.) under ZT and conventional tillage (CT) following three different annual crops. Significant previous crop × tillage system interactions in both years, indicated that forage crop establishment and dry matter production were lower under ZT than CT when the preceding crop was wheat (Triticum aestivum L.), however, no significant differences were observed when the preceding crop was either field pea (Pisum sativum L.) or canola (Brassica napus L.). Significant previous crop × forage species interactions for crop establishment indicated that while alfalfa was unaffected by previous crop type, emergence of meadow bromegrass was reduced when wheat was the previous crop. Significant previous crop × tillage system interactions for plant development indicated that development of both forage species was temporarily delayed under ZT when wheat was the previous crop. No treatment effects were observed for year after establishment dry matter production. A second experiment, conducted under conditions of post-seeding drought, assessed the impact of spring wheat straw management on establishment of alfalfa and meadow bromegrass under CT and ZT. Superior establishment of both alfalfa and meadow bromegrass under ZT was attributed to higher levels of soil water under ZT. Straw management (removal vs. returned to land) had no effect on either forage species. Results of these studies indicate that ZT is a feasible alternative for establishing forage crops, even where levels of previous crop residue are very high. Key words: Direct-seeding, straw management, wheat, canola, field pea, Haun stage, forage