Nitrous oxide emissions from two sites in Southern England during winter 1981/1982

Nitrous oxide fluxes from soil surfaces were measured during winter 1981/82 on two fallow sites, a loamy sand and a clay loam, that had been watered to field capacity and fertilised at the rate of 200 kg N ha −1 on the 5 October 1981. Highest fluxes were obtained in the sampling period immediately after fertiliser application. They were in the range 3.5–20 g N 2 ON ha −1 day −1 on the loamy sand, and declined rapidly from a peak of almost 165 g N 2 ON ha −1 day −1 on the day following fertiliser application on the clay loam. The temperature during this period was in the range 6.5 to 14°C. As soil temperature declined during the sampling periods in December (−2 to 3°C) and February (4.5 to 6.5°C) and nitrate was leached in the subsoil, N 2 O evolution became very low (<1 g N 2 ON ha −1 day −1 ). Rainfall over the whole sampling period from early October to mid‐February was 282 mm. On both sites there was a very high degree of variability within the sites at any sampling time.