Enhancing Plant Biodiversity, Soil Health and Agroecosystem Resilience: The Role of Cereal-Legume Crop Rotations

Agroecosystems must maintain high productivity over time and contribute to restoring the biodiversity and functionality of soils while agroecosystems yield the food we eat; however, the diversity related to food and agriculture has been shrinking. With this systematic review, the narrative and evidence map synthesized existing evidence about how cereal-legume rotations (as a form of diversifying crop diversity) could improve the diversity and function of the plant and functional aspects of biodiversity while restoring the soil health and agroecosystem resilience. A PRISMA 2020 report has been created alongside this work. This evidence will be used to understand improvements in soil physical and biological traits, nutrient cycles, and biologically fixed N, regulated pests/diseases/weeds, productivity and yield stability, environmental efficiency, and outcomes. In addition, several pieces of evidence were included and explained concerning the N cycle in cereal-legume rotations. When used compared to monoculture cereal systems, cereal-legume rotations lead to improved soil structure, activity, and nutritional status (N fixing) and may decrease pests and disease; these conditions often promote a better harvest or lead to higher and/or more stable productivity. Crop residue-based SOC increases are generally moderate in duration and degree. The increase in microbial biomass occurred more quickly over the years. For the environment, cereal-legume rotations generally achieve a lower total environmental efficiency due to lower N fertilizer inputs (N fixing), which means a lower C footprint per ton of production of crops, yet this strategy can also cause some environmental consequences, such as increasing N2O emissions (due to over N fixing), which cause global warming and nitrate leaching when N is fixed in excess, not coupled with crop requirements, creating pollution. The rotation is context-dependent, so each site-specific system needs to be analyzed to improve trade-offs to yield, productivity, and environmental conservation.