Journal of Advances in Biology & Biotechnology

Agricultural specialisation has increased the efficiency of producing a narrow set of commodities, yet it has also simplified biological processes that maintain soil function and has concentrated production, market and dietary risks. Crop diversification is therefore promoted as a means of restoring soil health while strengthening food and nutrition security. The relevant evidence, however, spans agronomy, soil ecology, food systems and nutrition, and the strength of the causal links differs markedly across these domains. This critical narrative review integrates evidence on temporal rotations, cover crops, intercropping and farm-level crop portfolios, with particular attention to the mechanisms connecting diversification to soil organic matter, aggregation, nutrient cycling, microbial communities, water regulation, crop productivity, yield stability, household access to food and dietary quality. The evidence is strongest for improvements in below-ground biological activity, aggregate stability, resource-use complementarity and production resilience when diversification increases functional contrasts among crops and is sustained for sufficient time. Average yield effects are generally neutral to positive, but vary with crop identities, baseline management, climate, soil properties and the treatment of non-harvested cover crops in productivity calculations. Nutrition effects are less direct. More diverse production can broaden food availability and reduce seasonal or market risk, yet household dietary gains are often small after controlling for market access, income, land, livestock and other determinants. Soil-health improvements support nutrition primarily by stabilising production and livelihoods rather than by automatically translating into more diverse diets. The principal weakness in the literature is a fragmented causal chain: soil studies rarely measure food-access or dietary outcomes, while nutrition studies often use crop counts without measuring soil functions or long-term productivity. Effective diversification therefore requires context-specific design, enabling markets, seed systems, knowledge, labour arrangements and policies that reward ecosystem services without sacrificing household income. Future research should combine long-term field experiments with farm-economic and dietary measurements, use functional rather than purely taxonomic diversity indicators, and test distributional outcomes across gender, farm size and market environments.