EVALUATION OF TWO BUFFERING METHODS FOR ESTIMATING SOIL BUFFERING CAPACITY AND LIME REQUIREMENT IN FACULTY OF AGRIC EXPERIMENTAL FARM, UNIBEN

ABSTRACT

Determining Lime Requirement (LR) and Soil Buffering Capacity (SBC)is important in adjusting soil pH to a desirable level, the study aim at evaluating two buffer methods for estimating soil buffering capacity and lime requirement in faculty of Agric Experimental Farm, UNIBEN. The study was conducted in soil samples collected at 0-15 and 15-30 cm soil depths from Agric experimental farm (AEF), some physical and chemical properties were determined using standard laboratory procedure while the LR was determined by using Ca(OH)2 titration method (CaHTM) and Shoemaker equilibration method (SEM). The Ca(OH)2 titration method involved titrating duplicates of 5 g soil samples with increasing amount (0, 1.5, 2, 2.5, 3 ml) of 0.022 M Ca(OH)2 and the pH recorded after shaking after for 1 hour. The CaCO3 equivalent of the Ca(OH)2 added was calculated in ton CaCO3/ha. A buffer curve was constructed as pH versus ton CaCO3/ha to access the varying impact of 0.022 M Ca(OH)2 of the pH on the soil solution in buffering capacity was determined by taking the slope reciprocal of the buffer curve. The shoemaker equilibration method involved equilibrating 10 g of soil which with 20 ml shoemaker buffer solution for 10 minutes and pH of the soil-shoemaker suspension was determined using a pH meter, the lime requirement was extrapolated from the scale of shoemaker buffer method. The LR from both methods were compared to determine the suitability of each method to determine LR in the study area. The results of the soil were predominantly sandy and falls into the loamy sand classification. Sand, Silt and Clay have mean values 865.40, 40.00 and 94.60 gkg1 respectively. The pH, OC, TON and Av.P had mean values of 4.96, 12.71 gkg1, 0.64 mgkg1 and 3.21 mgkg1 respectively. CEC, ECEC, BS have mean values of 2.18 Cmolkg1 m, 3.41 Cmolkg1 and 62.05 % respectively. In estimating the LR using the CaHTM was not significantly different from the shoemaker method (SMP), the SMP and CaHTM had mean LR value of 4.66 and 5.72 ton CaCO3/ha. The SBC have mean values of 0.44 and 0.39 considering the CaHTM.