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, differing in texture (sandy loam and silty loam), are frequently used for intensive crop production. Rates were estimated using a closed soil cover box technique. N2O-losses obtained were scrutinised with physical, chemical and microbiological properties of the soils as well as with climatic data. Large 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 observation, two situations 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 1 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.