Accession of SO2-4 sulfur from Tongan rainfall

Abstract

Accession of SO42- S from rain in Tonga has been assessed as approximately 6 kg S ha-1 year-1 from analysis of rainwater collected at three sites on two islands over a period of 365 days. The accession is of similar magnitude to crop removal of soil S. This accounts for the absence of S deficiencies in crops grown on andesitic soils which, on the basis of low to very low levels of adsorbed sulfate and low plant yields in glasshouse trials, were considered S-deficient. From consideration of ion ratios, it was established that sea spray/marine aerosol is the major source of SO42- S in Tongan rainwater.