Soil sulfur supply assessment using anion exchange resin strip-plant root simulator probe

A new soil test method for determining soil available sulfur (S) using an a nion exchange resin strip, a specially pretreated anion exchange membrane e ncased in a plastic applicator-Plant Root Simulator Probe, was evaluated. S amples of 18 China soils were collected from the 0-20 cm layer, dried, siev ed, and analyzed for available S using four chemical extracting solutions: 0.01 mol calcium chloride (CaCl2) L-1, 0.01 mol calcium dihydrogen phosphat e [Ca (H2PO4)(2)] L-1, 0.016 mol potassium dihydrogen phosphate (KH2PO4) L- 1, and 0.5 mol sodium bicarbonate (NaHCO3) L-1 (pH 8.5). Available S in soi ls was also extracted by a resin strip method with 24-hour and 2-week buria l times. Pot experiments were conducted to compare plant response to determ ined soil-available S. Results showed that soil-available S extracted by th e resin strips at 24 hour and 2 week burial times was significantly correla ted with S extracted by the chemical methods, especially highly and signifi cantly correlated with available S by 0.01 mol Ca (H2PO4)(2) L-1 (r(2) = 0. 725*** and r(2) = 0.600***) and 0.016 mol KH2PO4 L-1 (r(2) = 0.706*** and r (2) = 0.540***), respectively. Resuits also showed significant correlation between S availability by the resin strips at the two burial times and plan t S uptake (r(2) = 0.594***, r(2) = 0.401** for corn and r(2) = 0.773***, r (2) = 0.546*** for rice). Furthermore, results showed significant correlati on bt tween determined S by the resin strip at the 24 hour burial time and relative dry matter yield for corn (r(2) = 0.494**) and rice (0.687***), re spectively. An anion exchange resin strip was found to be a suitable altern ative method in the evaluation of S bioavailability in soils.