Abstract
The efficiencies of sulphur coated urea (SCU), urea and (NH4)2SO4 a nitrogen sources for maize and Sudan grass in a calcareous soil were compared. The apparent nitrogen recoveries by the maize crop in 80 days from SCU, urea and (NH4)2SO4 were 69·4, 36·5 and 50·4 per cent respectively. Similar trends in N recovery using Sudan grass as a test crop were observed, although recovery was lower. Sudan grass absorbed significantly larger amounts of K and Mg when SCU was used as the nitrogen source, especially at higher rates, as compared to urea. With (NH4)2SO4 and SCU as sources of uptakes of Ca and Mg by Sudan grass were similar.
