Abstract
The effects were studied of adding four nitrogenous sources (100 p.p.m. N on dry soil basis) to a Bangladesh laterite (pH 4·2) lacking autotrophic nitrifiers on mineral-N changes during aerobic incubation (30°C) for six weeks. Ammonium sulphate addition depressed nitrate accumulation, suggesting that autotrophic nitrification was not operative. Although ammonium-N accounted for most of the nitrogen mineralized from the organic nitrogen sources, nitrate-N accumulated to the extent of 7·0 p.p.m. from oxamide, 19·0 p.p.m. from urea and 34·8 p.p.m. from dried blood. Results are discussed in relation to the occurrence of heterotrophic nitrification in the soil.
