thus improving the natural fertility of the soil. CRA-W teams have been conducting crop combination trials incorporating leguminous plants.
Crop combination consists of cultivating several species mixed together on a plot. Although widespread until the 1950s, cereal/protein-based crop combinations fell into disuse with the development of modern agriculture.
Nowadays, this practice is used in organic farming because it is beneficial to crop rotation management and is also arousing interest among traditional farmers. Although it is more complicated to manage for farmers and downstream sectors, it provides a strategy for improving the resilience of crops, especially in low-input systems.
Firstly, crop combination generally leads to a stable yield over time, thanks to the complementarity between species with respect to growth factors such as light, water, and nutrients.
Secondly, in the special case of the cereal/protein-based crop combination, weed control is achieved using cover species sown with an appropriate density.
Thirdly, such combinations provide resistance to disease and pests, acquired through a physical barrier to airborne diseases, due to the lower density of each species and the choice of resistant varieties.
Fourthly, from an environmental point of view, a cereal/protein-based crop combination can have a direct beneficial effect as an additional nitrogen and pollen source. Finally, by reducing the phytosanitary pressure, it also has an indirectly positive effect on pollinators, for example.
As part of the SymBIOse project, the investigations are specifically targeted at three leguminous plants: protein peas, faba beans, and lentils. This prioritisation is based on the scale of the challenges faced by the different sectors, a lack of knowledge, and the technical obstacles associated with these species. For research purposes, a “crop succession” trial designed to compare the effect of intensifying rotated leguminous plants on telluric diseases was carried out by planting successions of crops and pure intercrops (single species) or combined crops (several species mixed). Several varietal and seed density trials were set up to determine the impact of these cultivation parameters on flowering, yield or soil contamination on the plot. Finally, trials conducted on micro-plots will make it possible to test the response of innovative crop combinations to challenges specifically related to the synchronicity of ripening for harvesting, maintaining, or improving yields or even the feasibility of sorting.
Funding: Interreg V project partially subsidised by CRA-W, Feder and SPW (DGO3). Convention 1.2.219 SymBIOse