Soil organic sulfur mineralization in the presence of growing plants underaerobic or waterlogged conditions

Pot culture experiments are described which attempt to identify soil organi c S mineralization and availability to plants under aerobic or waterlogged conditions. Several organic S fractions were determined using existing frac tionation techniques before and after the growth of corn (Zea mays L.) or r ice (Oryza sativa L.) seedlings for four successive harvests. Net mineraliz ation occurred in organic S fractions including hydriodic acid-reducible S, Raney-nickel reducible S and non-reducible S and all fractions decreased g radually during plant growth and decreased more in the first two harvests. The amount of S mineralized from organic S during rice growth under waterlo gged conditions was more than that during corn growth under aerobic conditi ons and this contributed to the greater amount of S taken up by rice seedli ngs. On average for the four soils tested, 70 and 82% of S taken up by four harvests of corn and rice seedlings, respectively, was derived from organi c S calculated by the difference between the S uptake by plant and the decr eased amount of inorganic sulfate in soils. All of the S fractions investig ated contributed available S for plant uptake under either aerobic or water logged conditions. (C) 2001 Elsevier Science Ltd. All rights reserved.