Above- and belowground biomass production in maize-tropical forages intercropping systems

Increasing food production remains a major challenge, particularly in the face of soil degradation, nutrient depletion, and the impacts of climate change. In this context, deep and abundant root systems play a pivotal role in improving soil structure, enhancing nutrient and water uptake, and increasing carbon sequestration. This multifunctionality of root systems is critical for building resilient cropping systems under climate change. This study assessed root traits and biomass accumulation in maize intercropping with tropical forages, Urochloa brizantha (palisade grass) and Megathyrsus maximus (guinea grass), to evaluate impacts on root development, distribution, accumulation, and total biomass production during a two-year field experiment in Torrinha, São Paulo, Brazil (Brazilian savanna). Conducted over two years in Brazilian savanna, the experiment compared five systems: maize, palisade, and guinea grass monocultures, and their respective intercropping with maize. Root traits (length, surface area, volume) were analyzed across vertical and horizontal soil profiles up to 1 m depth. Results showed that intercropping systems increased root length, surface area, and volume by 26–40 % compared to maize monoculture. Total biomass at 150 days after sowing was 21 Mg ha⁻¹ in intercropping systems, 17.6 Mg ha⁻¹ in maize monoculture, and up to 14.7 Mg ha⁻¹ in forage monocultures. At 250 days, forage monocultures surpassed all systems in total biomass (up to 14.5 Mg ha⁻¹), while intercropping maintained 7.7 Mg ha⁻¹. Root biomass in maize monoculture reached 1.2 Mg ha⁻¹, while intercropping systems achieved 2.3 Mg ha⁻¹, (90 % higher) and forage monocultures reached up to 4.4 Mg ha⁻¹ (270 % higher). A key finding was the superior soil exploration by intercropped systems, evidenced by 30 % of the root biomass being located in the maize inter-row zone, an area practically unexploited in the monoculture. Intercropping produced more extensive and better-distributed root systems compared to monocultures, offering potential benefits for subsequent crops with no significant penalty to maize grain yield. These findings highlight the potential of maize-tropical forage intercropping to boost belowground biomass, improve soil structure, and enhance carbon sequestration in tropical agriculture. This strategy offers a sustainable pathway to increase soil health, crop yields and resilience while supporting climate mitigation goals.