Weed populations in a field are relatively constant from year to year whereas insect and disease outbreaks, although they can have dramatic effects, can be sporadic.
Crop rotation can be a valuable part of an integrated weed controls strategy. Rotation regularly changes the crop, soil preparation practices, subsequent soil tillage, and weed control techniques in a field. All of these affect weed populations. Weed populations utilize specific ecological niches that are similar to the crops on which they proliferate, or they take advantage of conditions associated with that crop.
Diverse crop rotation creates an unfavorable environment for specific weeds and thus delays or deters the adaption of that population to the agroecosystem. Crop rotation is a preventive tactic that reduces the weed seedbank size and diversity.
Summer annual weeds, for example predominate on a corn/soybean rotation because both crops and weeds are summer annuals. This is because crops rotation provides continuous and evenness of a wider diversity of species is favored.
Weed control by crop rotations
