SULFUR SOIL TESTING

A wide range of extractants have been used to extract S from soils but correlations with plant response have generally been poor. Direct evi dence that ester sulfates contribute to plant S supply lead to the dev elopment of the 0.25 M KCl extract heated at 40 degrees C for 3 hours. Sequential extraction showed that this extractant removed 5.9% of est er sulfates from unfertilised soil. Support of the efficacy of the ext ract was obtained using specific radioactivity data from plants and so il extract.