Competition between corn and a living mulch

Abstract

Living mulches in row crops can reduce soil erosion, conserve soil moisture and control weeds; however, unless suppressed, they may also compete with the primary crop for light, nutrients and water. Therefore, the effects of mulch suppression were assessed on the development and yields of silage corn (Zea mays L.) in Truro, NS.In 1995 and 1996, silage corn was grown in a living mulch composed of white clover (Trifolium repens L.) and mixed grasses in a 2 × 5 factorial design with eight replications. There were 2 levels of applied N: 0 and 115 kg N ha−1. The mulch was suppressed by: herbicide bands, roto-tilled strips, a combination of herbicide and roto-tillage, applied straw, and complete eradication with conventional tillage and herbicide applications (unmulched control treatment). Mulch between the corn rows was mowed several times, early in the season, to reduce competition.In 1996, the control treatment yielded 11583 kg ha−1, significantly more than 6844 kg ha−1 in the combined herbicide and rototilled treatment, but in 1995 yields were not significantly different (P > 0.05) between these two treatments. Where only one method of mulch suppression was used (either roto-till or herbicide), corn yields in plots with living mulch were reduced by 39 to 72% relative to control plots. In both years, corn yields were higher at 115 kg N ha−1 than at 0 kg N ha−1. Yields in the mulched plots were 27% lower in 1996 than in 1995, probably as a result of a late June 1996 frost. In addition to the increased risk of frost damage, the living mulch also delayed corn emergence and development. While there may be some reductions in herbicide use with living mulch, the risk in cool temperate climates of delayed development and reductions in yield may limit the use of living mulches to cool season crops. Key words: Corn, frost, living mulch, reduced tillage, soil moisture