Crop rotation has long been considered one of the simplest and most effective tools for managing
weeds. In this paper, we demonstrate how crop rotations can be strategically arranged to harness a
novel mechanism of weed suppression: weed-weed competition. Specifically, we consider how crop
stacking, or increasing the number of consecutive plantings of a single crop within a rotation, can
decrease the size of the weed seed bank, by forcing weeds to compete with each other in similar
environments for longer periods of time, while still reaping the traditional benefits of crop rotation.
Using an annual plant model, we investigate the theoretical effects of stacked crop rotations on weeds
that have different life-history strategies and phenology. Our results show that when weeds compete
within a season, stacking can reduce the weed seed bank compared to rotations without stacked crops.
Although more research is needed to fully understand the effects of crop stacking on other aspects of
the system, such as insect pests and diseases, our research suggests that crop stacking has the potential
to improve weed suppression without additional inputs, and their associated costs and externalities.
More generally, improving management by changing the temporal arrangement of disturbances is a
novel, process-based approach that could likely be applied to other weed management practices, such
as mowing and herbicide application, and which could involve mechanisms other than weed-weed
competition. Leveraging this new application of existing ecological theory to improve weed
management strategies holds great promise.