SOIL SULFUR SUPPLY ASSESSMENT USING ANION EXCHANGE RESIN STRIP-PLANT ROOT SIMULATOR PROBE

Abstract

A new soil test method for determining soil available sulfur (S) using an anion exchange resin strip, a specially pretreated anion exchange membrane encased in a plastic applicator-Plant Root Simulator Probe, was evaluated. Samples of 18 China soils were collected from the 0–20 cm layer, dried, sieved, and analyzed for available S using four chemical extracting solutions: 0.01 mol calcium chloride (CaCl2) L−1, 0.01 mol calcium dihydrogen phosphate [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 soils was also extracted by a resin strip method with 24-hour and 2-week burial times. Pot experiments were conducted to compare plant response to determined soil-available S. Results showed that soil-available S extracted by the resin strips at 24 hour and 2 week burial times was significantly correlated with S extracted by the chemical methods, especially highly and significantly correlated with available S by 0.01 mol Ca (H2PO4)2 L−1 (r2=0.725*** and r2=0.600***) and 0.016 mol KH2PO4 L−1 (r2=0.706*** and r2=0.540***), respectively. Results also showed significant correlation between S availability by the resin strips at the two burial times and plant S uptake (r2=0.594***, r2=0.401** for corn and r2=0.773***, r2=0.546*** for rice). Furthermore, results showed significant correlation between determined S by the resin strip at the 24 hour burial time and relative dry matter yield for corn (r2=0.494**) and rice (0.687***), respectively. An anion exchange resin strip was found to be a suitable alternative method in the evaluation of S bioavailability in soils.