Abstract
The objective of the study was to test the Shoemaker et al. (SMP), Yuan, and Woodruff methods of determining lime requirement (LR) for 23 acidic soils of Sikkim to achieve soil pH 6.0 and 5.5 (LR 6.0 and LR 5.5). The results revealed that the precision of the soil buffer pH increased as the initial buffer pH of SMP and Yuan approached the desired pH. The Yuan buffer pH was less precise among the tested buffers. The Woodruff buffer was as precise as the SMP buffer for measuring the LR 6.0 and LR 5.5. The usual SMP buffer of pH 7 .5 and Woodruff of pH 7 .0 can be used to calculate the LR values by use of linear regression equations. The SMP initial buffer pH of 5.5 gave the best result for measuring the LR 5.5 than the other methods and buffers pH. Regression equations can be used for calculating the LR rates to pH 6.0 and 5.5 for the methods and modifications tested. The incubated lime requirement (LR 6.0 and LR 5.5) was highly correlated with soil pH, exchangeable Al and total acidity.
