Winter cover crops to reduce herbicide inputs in maize crops

A field study was undertaken in 2016/17 to evaluate the effects of winter cover crop residues on the emergence and growth of in situ weeds, required herbicide inputs and yields of maize (Zea mays) in comparison to a winter fallow. Weed ground cover at maize canopy closure was 81-85% less than the winter fallow in plots with Italian ryegrass (Lolium multiflorum), oats (Avena sativa) and prima gland clover (Trifolium glanduliferum) residues and 57% less in faba bean (Vicia faba). Ryegrass and oats residues maintained ground coverage of >70%, while clover had only 6% at canopy closure, but suppressed weeds similarly. In the absence of herbicides maize silage yields in plots with cover crop residues were similar to those in herbicide treatments, although maize establishment and growth was slower in oats and ryegrass.