Fallow is a farming technique in which arable land is left without sowing for one or more vegetative cycles. The goal of fallowing is to allow the land to recover and store organic matter while retaining moisture and disrupting pest life cycles and soil borne pathogens by temporarily removing their hosts. Crop rotation systems typically called for some of a farmer's fields to be left fallow each year.

The increase in intensive farming, including the use of cover crops in lieu of fallow practices, has caused a loss of acreage of fallow land, as well as field margins, hedges, and wasteland. This has reduced biodiversity; fallows have been the primary habitat for farmland bird populations.