Balancing productivity and emissions: the role of Tithonia diversifolia in tropical silvopastoral system

Abstract

Approximately 22% of total anthropogenic greenhouse gas (GHG) originate from agriculture and livestock. Therefore, finding alternatives to mitigate these emissions is crucial for the sector. GHG emissions and soil parameters were quantified in an exclusive grass system (EGS) and a silvopastoral system (SPS) over one year in southeastern Brazil, utilizing Tithonia diversifolia. Our objective was to assess in both EGS and SPS the microclimate conditions, GHG emissions, emission intensity, inorganic nitrogen, carbon stock, and fractionate soil organic matter. Four grazing cycles were conducted over one experimental year to measure GHG fluxes, including methane (CH₄), nitrous oxide (N₂O), and carbon dioxide (CO₂), from the soil, employing the static chamber technique linked to a cavity ring-down spectroscopy (CRDS) analyzer. Soil samples were collected at the end of the experimental period. Treatments were assigned using a completely randomized design with four replicates. GHGs were expressed in CO₂ equivalent (CO₂eq). The soil temperature in the SPS was 0.6 °C lower than in the EGS (p = 0.024). Soil carbon variables did not show significant differences between systems. Cumulative emissions in CO₂eq were comparable among treatments but varied across cycles (p < 0.001). Emission intensity (mg CO₂eq kg⁻¹ accumulated forage mass) was lower in SPS than in EGS (p = 0.002). The absence of discernible differences in GHG emissions and soil carbon variables between systems may be attributed to the short-term establishment period. The intensification of the pasture system emerges as a crucial factor in achieving climate change mitigation, and the utilization of T. diversifolia in SPS appears as a promising alternative to increase productivity without increasing emissions.