Soil Mineralizable Sulphur: A Sulphur Availability Index

摘要

Forms of sulphur (S) and S supplying capacity of Mollisols of low, medium and high category of available S, were investigated from tarai region. One hundred and twenty surface-soil samples were collected, and grouped into low (A), medium (B) and high(C) available S content. Among 120 samples, 10 representative soils were selected and analyzed for their physico-chemical properties. The soils were neutral in reaction; EC ranged from 0.43 to 1.26 dSm; and organic carbon content ranged between 7.2 and 36.1 g kg~(-1). Available S in soil ranged from 6.25 to 36.25 mg g~(-1); organic-S and inorganic-S ranged from 362 to 538 mg kg~(-1) and 278 to 1178 mg kg~(-1), respectively. Sulphur mineralization study indicated that mineralization increased up to the 10th week and then declined. Highest amount of mineralizable -S content was obtained at the 8th week in all the three groups of soils. Order of S-mineralization was found as group C > group B > group A. The maximum cumulative S-mineralization was noticedin group B soil. Group C soil did not show a consistent pattern.