Use of ion‐exchange resin to evaluate the bioavailability of sulfur in the soil

Abstract Samples of 22 soils of the State of Sao Paulo, Brazil were collected from the 0–20 cm layer, dried, sieved, and analyzed for sulfur (S) utilizing the following extracting solutions: (a) calcium phosphate [Ca(H2PO4)2], 500 mg P L‐1 in 2.0 mol acetic acid (HOAc) L‐1, (b) 1 mol ammonium chloide (NH4C1) L‐1, (c) 0.5 mol ammonium acetate (NH4OAC) L‐1 in 0.25 mol HOAc L‐1, (d) ion exchange resin ‐ Resin 1 ‐ (2.5 cm3 of soil + 2.5 cm3 of resin in water and further extraction with 50 mL 0.8 mol NH4Cl L‐1 in 0.2 mol hydrochloric acid (HCl) L‐1), (e) ion exchange resin ‐ Resin 2 ‐ (5.0 cm3 of soil + 5.0 cm3 of resin and 25 mL 0.8 mol NH4Cl L‐1 in 0.2 mol HCl L‐1), (f) ion exchange resin ‐ Resin 3 ‐ (5.0 cm3 of soil + 2.5 cm3 resin and 25 mL 0.8 mol NH4Cl L‐1 in 0.2 mol HCl L‐1). Amounts of 2 kg of each soil, in four replicates were limed in order to reach a base saturation of 70% of the cation exchange capacity (CEC). After a period of incubation of 30 days all nutrients, except S, were added to the soil a...