Spatial variability of soil attributes and risk of phosphorus loss in different soil classes of the Potengi River Basin, Brazil.

The spatial variability of soil attributes plays an important role in hydrological processes, soil fertility, and environmental conservation in tropical semiarid regions. Texture, organic matter (OM), and available phosphorus (P) directly influence nutrient dynamics and the risk of phosphorus export to water bodies. This study analyzes the spatial distribution of soil texture, OM, and P in different soil classes of the Potengi River Basin (PRB), assessing their relationship with weathering and phosphorus mobility. A total of 110 soil samples were collected from different pedological classes, following standardized physical and chemical analysis methods. The data were spatially interpolated using the IDW method in ArcMap 10.8, and statistical analyses, including correlation, principal component analysis (PCA), and two-way cluster analysis, were applied to identify distribution patterns. The results revealed a predominance of sandy soils, moderate OM levels, and high phosphorus content. PCA identified two soil groups: Group 1, composed of more developed soils with higher clay and OM content, and Group 2, consisting of less developed soils with a higher risk of phosphorus export. The negative correlation between P and clay content emphasized the influence of texture on nutrient retention and mobility. This study highlights the relevance of spatial analyses for soil quality assessment and provides essential insights for sustainable land management strategies aimed at mitigating diffuse phosphorus pollution in semiarid watersheds.