Field Studies of the Soil Atmosphere Ii. Occurrence of Nitrous Oxide

Summary Studies were made of the seasonal changes in the occurrence of nitrous oxide in the atmosphere of two clay soils. During the winter of 1971‐2 the nitrous oxide concentrations at both sites were in the range 20‐50 ppm. Levels increased with rising soil temperatures in spring, the mean values reaching 50‐170 ppm in May; some individual samples contained 1500‐6500 ppm. The level of nitrous oxide was inversely related to the oxygen content of the soil atmosphere and was also correlated with the nitrate and nitrite concentration of the soil water, but could not be correlated with either the proximity of field drains, soil moisture content or rainfall.