Topographic modulation of soil functional indicators in shaded coffee agroforestry systems: a multivariate and...

Brazil is the world's leading coffee producer and increasingly adopts shaded agroforestry systems to enhance sustainability. However, the influence of topography on soil functionality within these systems remains insufficiently understood. This study evaluated soil physical and chemical properties across slope positions (Upper, Middle, and Lower Thirds) and depths (0-60 cm) in a shaded coffee agroforestry system using multivariate statistics and Bayesian network modeling. Results revealed that upper slope positions exhibited greater macroporosity (15-20%) and lower bulk density (1.10-1.15 g cm⁻³), whereas lower slope positions accumulated higher total organic carbon (2.5-3.0%) and microporosity (28-32%). Principal Component Analysis indicated that topography modulated soil porosity and carbon distribution, with total organic carbon (TOC) positively correlating with nutrient availability and negatively with acidity. Bayesian network analysis identified TOC as the most influential attribute, displaying the highest expected influence (1.25) and strength (1.15), along with elevated centrality in conserved environments. These results demonstrate that TOC functions as a central integrator linking soil structure, chemistry, and fertility across topographic gradients. Overall, shaded coffee agroforestry enhanced soil quality and functionality, particularly in upper slope areas, underscoring its potential for sustainable land management in tropical landscapes.