Ground covers are an additional tool for growers; they can improve soil structure, fix atmospheric nitrogen, attract beneficial insects, improve pollination, etc.
The most common mixtures for providing organic matter and nitrogen to the soil are made up of grasses and legumes in an 80-20 ratio. They are considered green manures because of the amount of biomass they produce in short periods of time and the nitrogen they provide thanks to the legumes and the symbiosis with bacteria of the Rhizobium genus.
Sometimes mixtures of plants that produce a lot of flowers are sown between crop rows or in the margins. Mixtures of species with staggered blooms are chosen to attract and provide refuge for pollinators and other beneficial insects. These biodiversity structures in the form of flower bands have positive effects on pollination and on the survival of colonies of natural enemies of certain pests.
Some species such as crucifers (or brassicas) are used as biocides to reduce populations of certain nematodes, fungi and soil bacteria, and even prevent the germination of certain adventitious plants. One of the mechanisms, known as biofumigation, is the production of toxic substances generated by the decomposition of these plants.
