Extent and implications of weed spatial variability in arable crop fields

The integration of technologies and principles to assess, manage, and evaluate spatial and temporal variability has enabled the site-specific application of variable rates of agrochemicals. It is referred to as precision management. This article concerns with the potential of precision management for weed control. Weeds are heterogeneously distributed and show different levels of spatial aggregation. A better understanding of weed patchiness is necessary for precision weed management. Studies reviewed in this article showed that significant reduction in the amount of herbicide can be achieved when the spatial variability of weeds is taken into account. It is often difficult, however, to obtain information on the spatial distribution of weeds with accuracy because it depends on monitoring techniques, scales of observation, and statistical methods applied. We conclude that the precision application of herbicides is one approach to managing weeds and it will be possible to achieve a drastic reduction in herbicide applications by using a combination of several different types of weed control strategies. Not only farmers with large fields but also those with small fields should have better access to information on spatial variability to make decisions for weed control.