Cropping diversity and input use affect weed competition
Of the various pests affecting crop growth weeds are among the most visible and potentially the most damaging. Changing markets, higher input costs and technological change are having a profound impact on weed management decisions in Western Canada. While the decision to change management practices can be immediate the long term agronomic consequences of adopting a farm management system are not well understood. One objective of a long term study, established at Scott in 1995, was to investigate the impact of 3 levels of inputs and 3 levels of cropping diversity on in-crop weed competition. Weed biomass used as an indicator of weed competition, was found to be largely a function of input level decisions and the interaction of weed control operations with precipitation timing. Greater weed biomass in an Organic input system could be linked to a limited number of early season tillage operations occurring over a short window of opportunity near the time of seeding. Herbicides applied later in the growing season in the Reduced and High input system effectively delayed weed growth and reduced weed biomass. Weeds in the Organic input system tended to respond to June-July precipitation while weed growth in the Reduced and High input system increased as July precipitation increased. Differences between cropping diversities were less pronounced showing similar weed biomass trends over time.
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