Roots to Riches: Unearthing the Synergy of Intercropping, Microbial Interactions, and Symbiotic Systems for Sustainable Agriculture: A Review

Intercropping, especially legume-cereal systems, is a mixed farming approach that can improve agricultural resilience by addressing challenges such as soil degradation, biodiversity loss, and global change, all while promoting the sustainable production of protein-rich and nutritious food. However, its adoption in industrialized countries remains limited due to economic and technical challenges, as well as a fragmented understanding of soil–plant-microbe interactions, which hinders its complete optimization. This article provides an overview of the current situation and future perspectives on the importance of legume–cereal intercropping, with examples such as common bean–maize, soybean–maize, alfalfa–corn–rye, and legumes–pulses–little millet systems. These combinations highlight how intercropping can improve nutrient cycling, increase root growth, forage and grain yield, suppress soil-borne diseases, and promote soil microbial population and enzymatic activity. While it offers environmental benefits, practical challenges such as system design, management complexity, and cost-effectiveness must be addressed to encourage wider adoption. In preparing this review, we synthesized studies published between 2000 and 2025, with a particular emphasis on recent research from China and Southeast Asia. We also considered broader intercropping contexts, including energy crops, agroforestry systems, rice paddy co-cultures, and phytoremediation approaches. The review also highlights legume–cereal as a solution to sustainable soil management, ecosystem health, and the potential for increased nutritional food production in developed countries.