Assessment of Soil Buffering Capacity in Benue Farmlands and its Role in Mitigating Soil Acidity

Abstract

This study assessed the buffering capacity of selected farmlands across six locations (Gwer East, Otukpo, Konshisha, Ukum, Tarka, and Oju) using physicochemical analyses and a simulated acid rain experiment. Soil samples were analyzed for pH, organic matter, cation exchange capacity (CEC), particle-size distribution, and base saturation, and buffering capacity was determined using the ΔpH method. Results showed that soils were generally slightly to moderately acidic (pH 5.20–6.85), with notable spatial variability in key fertility indicators. Organic matter (2.60–4.68%) and CEC (5.60– 11.30 cmol kg−1) were highest in Gwer East and Oju, corresponding with higher base saturation and stronger buffering capacity, while Tarka and Otukpo recorded lower values and weaker resistance to pH change. Buffering capacity ranged from high (ΔpH = 1.00) in Gwer East to very low (ΔpH > 4.0) in several locations. Simulated acid rain exposure confirmed that soils with low organic matter, low CEC, and high sand content experienced greater material loss (up to 3.19%), whereas more clay- and organic-rich soils showed reduced degradation. Correlation patterns indicated that organic matter, clay fraction, CEC, and base saturation collectively govern soil resistance to acidification. The study demonstrates that soil buffering capacity in Benue farmlands is highly variable and strongly dependent on soil composition, highlighting the need for organic matter enhancement, liming, and improved nutrient management to sustain soil quality and agricultural productivity in the region.