Fall-seeded cereal cover crops differ in ability to facilitate low-till organic bean (Phaseolus vulgaris) production in a short-season growing environment

Reducing tillage in organic bean (Phaseolus vulgaris) production may be facilitated by strategic use of fall-seeded cover crops. This study characterized the effects of fall rye (Secale cereal L.), barley (Hordeum vulgare L.) and oat (Avena sativa L.) cover crops on soil environment, weeds, and bean growth and development. It was repeated twice in Manitoba, Canada with cover crop type and tillage treatments in a factorial experiment. Cover crops were seeded in fall each year (2010 and 2011). Greater cover crop biomass and lower available soil N at bean planting for rye was attributed to rye spring growth. In the till managed treatment, cover crops were tilled immediately before bean planting. Cover crop management in the no-till treatment involved flail mowing (18 days after bean planting in 2011 and 11 days after bean planting in 2012) in the fall rye treatment and flaming immediately after bean planting in the frost-killed barley, oat and control treatments. Rye reduced soil temperature and early season bean development. Bean population density was unaffected by tillage or cover management despite 5604 kg ha−1 of rye biomass at planting. Green foxtail (Setaria viridis) populations were decreased with rye only in no-till plots. Dandelion (Taraxacum officinale) was unaffected by treatments, while redroot pigweed (Amaranthus retroflexus) and barnyard grass (Echinochloa crus-galli) populations were lower in no-till plots. Rye reduced weed biomass but not bean biomass at harvest; however, bean yield was lower with rye compared with other cover crops in both years. It was concluded while frost-killed cover crops did not provide sufficient weed suppression, fall rye provided too much competition against the bean crop. No-till management did not improve rye's overall effectiveness.