Department of Soil Science and Agricultural Chemistry, Birsa Agricultural University, Kanke, Ranchi, Bihar, 834006.
A pot experiment with black gram was conducted with 21 acid sedentary soils (Alfisols) of varying pH (5.2 to 6.4) for selecting the most suitable chemical extractant for available sulphur and determine the critical limit of available S in these soils. All the extractants (except 1% NaCl and 0.001 NHCl) had significant positive correlation with the biological yield attributes of black gram. Monocalcium phosphate Ca(H2PO4)2. H2O was the best among the extractants tested and gave the highest degree of correlation with dry matter yield (r = 0.598**), S uptake in the control pots (r = 0.602**), Bray's per cent yield (r = 0.725**) and per cent S uptake (r = 0.817**) by black gram. The critical limit of available soil sulphur were 8.7 and 18.6 mg kg−1 with 0.15 per cent CaCl2 and Ca(H2O4)2H2O, respectively.
Chemical extractants, critical limit, sulphur, Alfisols, black gram
