Enhancing soil quality in the Brazilian semi-arid through integrated livestock–forest systems: a multivariate analysis approach

Integrated systems contribute to agricultural sustainability by promoting soil quality. This study evaluated the effect of integrated livestock-forest systems (ILF) with different spacings and crops on soil quality in the Brazilian semi-arid region. The studied systems included four ILF systems: ILF with sorghum (So), forage cactus (Fc), massai grass (Mg), and buffel grass (Bg), at spacings of 7 m (S7), 14 m (S14), and 28 m (S28) between strips of native trees viz. Caatinga. These systems were compared with an area of native vegetation (NV). Soil physical [soil texture, bulk density, macroaggregates, mesoaggregates, and microaggregates], chemical [pH, P, K⁺, Na⁺, Ca²⁺, Mg²⁺, soil organic carbon (SOC), total nitrogen (TN), isotope δ13C, particulate organic matter (POM), and mineral-associated organic matter (MAOM)], and biological properties [microbial biomass carbon (MBC) and soil basal respiration (C-CO₂)] were evaluated using multivariate PCA analyses and the multivariate stability index (multi-trait stability index—MTSI). The results show that ILF systems with grasses, particularly Mg and Bg, improve soil quality by reducing the loss of SOC, MAOM, TN, and MBC after the conversion from NV. In these systems (Mg and Bg), the gains of TN, POM, and MBC were up to 11%, 34%, and 35%, respectively. SOC was the variable most correlated with other soil attributes. The MTSI analysis identified the Mg S28 and Bg S28 systems as having the best average performance and stability across multiple soil characteristics. The use of MTSI was effective in classifying agricultural systems.