Integrating corn–brachiaria intercropping for enhanced soil carbon sequestration and sustainable agriculture in the cerrado

Intensive corn silage production in tropical regions, particularly within Brazil’s Cerrado, often leads to rapid soil degradation due to excessive nitrogen removal, biomass extraction, and consequent depletion of organic matter. In the absence of sustainable management practices, these systems suffer declines in fertility and resilience that undermine long-term productivity. This study investigates whether intercropping corn with Brachiaria grass (Urochloa ruziziensis), combined with strategic nitrogen fertilization, can improve soil structure, enhance soil organic carbon stocks, and stimulate microbial activity while maintaining high silage yields. A two-year field trial was conducted on a Cerrado Oxisol to compare a corn-brachiaria intercropping system with conventional monoculture corn silage under five nitrogen regimes: ammonium nitrate, inhibitor-treated urea, regular urea applied at 220 kg N/ha, a control without topdressed nitrogen, and a zero-nitrogen treatment. Soil health was evaluated by measuring bulk density, total organic carbon, and microbial activities, while corn silage yield served as an indicator of overall system productivity. Statistical analyses were performed using analysis of variance (p < 0.05) and Tukey’s test for multiple comparisons, and a multivariate approach employing principal component analysis (PCA) was applied. An initial correlation matrix was generated in RStudio to identify the most relevant variables, and the centroids parameter was used to cluster treatments within a two-dimensional space. Results revealed that intercropping markedly improved both the physical and biological attributes of the soil. Notably, bulk density exhibited an inverse relationship with microbial biomass and carbon fractions, including light fraction carbon and total carbon, indicating that high bulk density in compacted soils hinders microbial activity and degrades organic carbon quality. PCA uncovered complex interactions among treatments, with brachiaria-intercropped systems showing a 21% increase in carbon stock relative to monocropping (28 g/kg versus 23 g/kg) and enhanced light carbon levels, while nitrogen fertilization, particularly with ammonium nitrate and inhibitor-treated urea at 220 kg N/ha, was positively associated with microbial biomass. By increasing soil organic matter, stabilizing aggregates, and fostering a vigorous microbial community, the corn-brachiaria intercropping system represents a scalable, climate-smart strategy that mitigates soil degradation, boosts long-term carbon sequestration, and reinforces agroecosystem resilience against climate variability. These findings support Sustainable Development Goals 2 and 13, offering a compelling model for regenerative farming in tropical regions, providing a promising pathway to reconcile high-yield production with environmental stewardship and sustainable agricultural practices. This innovative approach transforms soil management by integrating ecological principles with agronomic productivity and inspires research on sustainable, carbon-positive agriculture.