Losses, through Denitrification, from Soil of Applied Inorganic Nitrogen even at Low Moisture Contents

Abstract

THE losses of nitrogen in gaseous form (oxides of nitrogen) through denitrification of inorganic nitrogen, particularly nitrate, added to water-logged soils is well known^1–3. Other workers^4–6 showed that nitrogen was lost by denitrification even from drained soils, that is, under non-water-logged conditions. These workers did not consider the effect of varying soil moisture content on the extent of denitrification, apart from ensuring that the soils were not water-logged. However, in drained soils water content may vary from, saturation (maximum water-holding capacity) down to the wilting percentage, in so far as plants are concerned, or even lower. Bremner and Shaw⁷ showed in incubation tests that a moisture content of approximately 60 per cent of the maximum water-holding capacity was critical, in that denitrification occurred only when soil moisture content exceeded this figure.