Long-term agroforestry effects on soil CO2 and NO emissions in the Brazilian semiarid region

Abstract

The Brazilian semi-arid region is highly vulnerable to climate change. This study evaluated greenhouse gas fluxes and soil properties under different land uses in this region. Agroforestry systems, agro-silvopastoral (AGSP) and silvopastoral (SILV), a traditional agricultural system (TR) characterized by slash-and-burn followed by fallow, and natural vegetation (NV) on Luvissolos were compared. C-CO₂ and NO-N fluxes were measured during the rainy and dry seasons using static chambers coupled to a portable gas analyzer. The total organic carbon (C) and nitrogen contents of the soil were determined, as well as gravimetric moisture, soil density, and particle density, enabling the estimation of total porosity and water-filled pore space (WFPS). During the rainy season, all managed systems showed higher WFPS than NV. In the dry season, water retention decreased in TR. C-CO₂ fluxes were higher in TR during the rainy season (51.33 mg m⁻² h⁻¹), while agroforestry systems and NV had the lowest emissions in both seasons. NO-N emissions were detected only during the rainy season, with higher values in NV (92.06 μg m⁻² h⁻¹). Agroforestry systems exhibited greater stratification and surface accumulation of C. The resilience index indicated that SILV had the greatest potential to restore C stocks at all depths, while AGSP showed lower resilience in deeper layers. In general, agroforestry systems, especially SILV, demonstrated greater potential to stabilize greenhouse gas fluxes and increase C storage in the soil. These systems can contribute to climate change mitigation and sustainable soil management in semi-arid environments.