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N20 emissions and denitrification N‐losses. precipitation, air temperature, soil moisture, bulk density and content of mineral N were monitored in 9 different agricultural soils in 6 European countries throughout the vegetation period (April to September) 1992 and 1993. N2O emissions and denitrification N‐losses were log‐normal distributed, reflecting high temporal changes. While small flux rates (< 2 g N ha−1 d−1) were detectable every day, high rates (> 10 g N ha−1 d−1) were measured after fertilization. An attempt to relate the emission variables to climate and soil variables was made through the use of correlation analysis. The mean N20 emissions from soil were significantly correlated with the soil properties clay, organic C and mineral N content and the amount of applied mineral N fertilizer. The best prediction of the N2O emission rates (r2 = 0.734) was achieved by multiple linear regression using the soil parameter clay and mineral N. Only 50% of the observed variation could be explained by the factors Corg and mineral N, which describe the substrate availability for microbial processes. No successful statistical model was found for the prediction of denitrification N‐losses.

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This review comprises a general description of nitrogen in soil water and the use of nitrogen fertilizer. The following investigations on nitrogen leaching and transformations are described: Investigations on drainage water. Losses of nutrients by leaching in agricultural production. Influence of nitrogen fertilizer on nitrate nitrogen content in drainage water. Nitrate reduction in the subsoil. Water balance and nitrogen balance by optimum plant production. The main conclusions are that the leaching of nitrogen as nitrate mainly occurs in the autumn and winter periods as a result of biological degradation of plant residues. Increased plant covering of the soil will decrease the nitrate leaching.