Legume-grass intercropping systems improve soil health and plant nutrition

Abstract

Abstract Background and aims Intercropping legumes and grasses presents a sustainable strategy to improve soil fertility, enhance crop productivity, and strengthen food security in low-input agricultural systems. This study investigated the effects of intercropping Vigna unguiculata with Eragrostis curvula on soil bacterial communities, extracellular enzyme activities, nutrient dynamics, and plant growth kinetics and nutrition. Methods Pre- and post-harvest soil samples were analysed for chemical and biological properties, and plant samples were assessed for growth and nutrient uptake. Results Intercropping resulted in a shift in soil bacterial composition, favouring phosphorus (P)-solubilising taxa such as Burkholderia and Pseudomonas , while reducing soil enzymes activities, including N-acetylglucosaminidase, β-glucosidase, nitrate reductase, and acid and alkaline phosphatases. Despite lower enzymatic activity, intercropped soils showed increased P and nitrogen (N) concentrations. Vigna unguiculata belowground biomass increased and established associations with P-solubilising bacteria from the Pseudomonas and Paenibacillus genera, which enhanced plant P concentrations, and P use efficiency. Eragrostis curvula showed variable growth across soil types but demonstrated increased reliance on atmospheric N, higher plant N concentrations, and improved uptake of soil-derived N. Intercropped V. unguiculata , increased reliance on atmospheric N, nodule weight, plant N concentrations, and specific N utilisation rates. Conclusions These findings highlight the potential of V. unguiculata and E. curvula intercropping to improve soil health, boost crop nutrition, and reduce dependency on external inputs, offering a viable solution for sustainable agriculture in resource-constrained environments facing challenges of climate change and soil degradation.