Forms of sulphur in relation to soil properties and sulphur availability to rice in old alluvial soils of Bihar

摘要

Surface soil samples from 20 sites in old alluvial belt of south Bihar plain were analysed for soil properties, forms of S and available S, with a number of extractants. Most of the total -S was present in organic form and ranged from 297-1352 (av.912) mg kg~(-1), organic -S from 291-1342 (av. 903) mg kg1 and sulphate -S 3.3 - 18.3 (av. 9.9) mg kg~(-1). Total -S was positively and significantly correlated with organic-S (r=0.999~(**)), sulphate=S (r=0.545~*) and water soluble -S (r=0.463~*). Organic -S was positively and significantly correlated with sulphate-S (r=0.535~*) and water soluble-S (r= 0.455~*). Similarly, sulphate-S was found to be significantly correlated with water soluble-S (r=0.848~(**)). This indicates the existence of dynamic equilibria among the different forms of S. Of the other soil properties, EC exhibited significant positive correlation with water soluble-S (r=0.576~(**)) and sulphate-S (r=0.529). CEC, clay, silt and silt + clay showed significant positive correlation with organic-S and total-S having r- values 0.699~* and 0.698~*, 0.895~(**) and 0.893~(**), 0.657~(**) and 0.659~(**) and 0.902~(**), and 0.902~(**) respectively. The available -S (extracted by different extractants) showed significant positive correlationwith water soluble-S and sulphate-S. A step down multiple regression analysis revealed that sulphate-S followed by water soluble-S pools contributed dominantly towards the various crop parameters.