Variation in Soil Physicochemical Properties Associated with Topography in Acidic Soils of Southern Zacatecas, Mexico: Implications for the Application of Soil Amendments

The abundant rainfall and rugged topography characteristic of southern Zacatecas promoted soil leaching. This differentiation in soil physicochemical properties, driven by leaching, results in higher-altitude areas having soils with high sand and aluminum (Al3+) content. The influence of altitude and soil units on acidity levels and the quantity of amendments required for the study region (the municipality of Momax) was determined. Samples were collected from sixty-one agricultural sites, based on pH data reported by INEGI in 1979 and variance estimated from an interpolated map. Principal component analysis was used to divide the samples into four contrasting groups. Group 4 exhibited the highest values for clay, organic matter, exchangeable cations, and cation exchange capacity (p < 0.05). Group 1 and 2 served as a transition zone; Group 3 showed the lowest pH values (mean of 4.7) (p < 0.05) and the highest levels of sand (65.5%), aluminum (0.83 cmol kg-1), and hydrogen (0.09 cmol kg−1) (p < 0.05). Given that 80% of the study area contains exchangeable aluminum, it is necessary to implement a future technological intervention plan, incorporating this study’s recommendations, as well as, the possibility of reducing cost by applying less CO3 amendment rates within a range from 0 to 1.76 t ha−1.