Denitrification in some tropical soils

Abstract

Denitrification has been studied in a range of near-neutral Ghanaian soils. The technique used was to add nitrate, alone or with glucose, to 10 or 15 g. samples and incubate at 30° C. and 70 or 160% of the water holding capacity. Changes in the nitrate and total nitrogen contents were then determined over a period of 14 days. Only small or non-significant losses of nitrogen occurred in the unsaturated soils, but larger and rapid losses were observed in the saturated samples. In the samples from under standing forest or old grassland denitrification proceeded without addition of a carbonaceous substrate, but a small addition was required in the cultivated and young grassland soils. The amount needed was much less than has been shown necessary for an equivalent nitrogen loss in a number of temperate zone soils. Evidence was obtained that nitrification and denitrification could proceed simultaneously in the same sample. It is c6nsidered that this supports the concept of a micro-mosaic of aerobic and anaerobic spots in a wet soil.