Similar names: mixed improved fallows, mixed intercropping, shade trees, relay intercropping

Cultivating mixed and improved fallows is a technique that aims at keeping yields high while maintaining the soil’s fertility and moisture. This can be achieved by growing two or more species in succession, sown at different times of the year on the same piece of land which positively influences each other while providing beneficial soil nutrients. This newly replenished soil should therefore never be left exposed but always covered by crops and mulch. Traditionally, farmers used to leave a section of their land to “rest” (= the fallow) for one year or more after a period of intense cultivation. This allows the soil to be covered by natural vegetation which restores nutrients, organic matter, and soil microbial activity necessary to make the soil fertile. However, with the increasing demand for resources, this practice is rarely used. To ensure long-term soil fertility, some farmers have come up with the solution of planting fallow plants, which can either be a tree, a shrub or a herbaceous cover crop – often a leguminous species, during the fallow phase. Fallow plants can then be used to: provide fodder, break cycles of pests (as some species are natural pest-repellents), attract honeybees, keep weeds away, shade crops, increase soil activity, and increase biodiversity. 

Mixed improved fallows can perform even better than having one fallow species on rotation. This is when two or more fallow species are combined with one traditional crop. Usually, one of the two fallow species grows to a tall height providing shade, while the other is usually a “nitrogen fixing” plant which restores nutrients in the soil.