Dinâmica da matéria orgânica do solo em sistemas de integração pecuária-floresta na região semiárida do Ceará, Brasil

Abstract

Although considered a natural solution to mitigate climate change, carbon sequestration in the Brazilian semi-arid region presents challenges. Due to its unique climatic and environmental characteristics, carbon sequestration (C) is more complex, which raises questions about the sustainability of agricultural development in the region. This study investigated the effects of integrated livestock-forest (ILF) systems with different spacings and crops on C storage, microbial activities, and soil quality in the semi-arid region of Ceará. The systems studied included agroforestry systems with sorghum (So), forage cactus (Fc), massai grass (Mg), and buffel grass (Bg), with spacings of 7 m (S7), 14 m (S14), and 28 m (S28) between strips of native vegetation (STN). After 6 years, soil samples were collected up to a depth of 0.5 m. The results showed that the conversion of Caatinga to ILF systems, particularly those with massai and buffel grass, has the potential to increase total soil organic carbon (SOC) and nitrogen (TN) stocks, the fractions of minerals-associated organic matter (MAOM) and particulate organic matter (POM), microbial biomass carbon (MBC), enzymatic activities, and the microbial quotient, resulting in positive impacts on soil quality. Moreover, the S28 and S14 spacings were the most promising for increasing SOC, POM, and MAOM fractions. While S7 showed a greater contribution to the maintenance of soil biomass and microbial activity. These results highlight the role of integrated systems in the maintenance and recovery of SOC, contributing to the adoption of more sustainable and efficient agricultural practices in the Brazilian semi- arid region.

Keywords: soil carbon, Caatinga, nature-based solution.