Temporal changes in N₂O-losses from two arable soils

N2O-loss rates from two soils were measured over a continuous observation period of 2 years. The two soils (sandy loam and silty loam) are frequently used for intensive crop production. Rates were estimated using closed soil cover box technique. Information obtained were compared with physical, chemical and microbiological properties of the soils as well as with climatic data. High temporal changes in N2O emission rates were found. The data were approximately log-normal distributed. In spring maximal values of 20 g N2O-N ha(-1) d(-1) were observed. According to this observations, two scenarios associated with high flux rates could be distinguished: 1. N2O production by soil at spring thaw and 2. N2O production within one week after N-fertilizer application. For both soils equal N2O losses were found, which are adequate to 2 kg N2O-N ha(-1) per year. From this data was calculated that N2O losses ranged from 0.8-1.5 % of the applied fertilizer N.