Field evidence on nitrogen losses by denitrification

Abstract. Evidence based on observations of colour, growth and measurements of stem nitrate on carrots and sugar beet, colour and yield of grass, and of yield of wheat in different areas of Britain showed that growth and yield may have been substantially reduced in the wet summer of 1985 due to deficiency of nitrogen following large losses by denitrification. An account of die processes involved is given, together with observations and tests on affected soils. These were compared with field measurements of denitrification also made in 1985, under barley.
Examination of climatic data suggests that there were several periods in May, June, July and August when the soils close to the surface would have been saturated for days on end, and in the presence of many tine roots typical of crops at that time of year, the onset of an anaerobic state and accompanying denitrification would have been highly likely. The field evidence in 1985 suggests that nitrogen losses may have been much higher than those reported previously from research station investigations.