Field Measurements of Natural and Fertilizer-Induced N2O Release Rates from Soils

The influence of the soil on atmospheric N2O was studied by In-situ measurements in 1976–1979 at several field stations near Mainz, Germany, where different soil types were located. Measurements were carried out using the closed chamber method and applying stainless steel capillaries allowing soil air sampling down to 60 cm depth. The N2O In soil was found to be produced and consumed simultaneously In the uppermost soil layer resulting In a net flux of N2O with release rates of 0.5–16 μg N2O–Nm−2h−1 on unfertilized natural as well as agriculturally used soils. After fertilization with mineral fertilizers the N2O release rates increased to values ≤43 μg N2O–Nm−2h−1. The total amount of fertilizer-N released Into the atmosphere as N2O was determined to be 0.01–0.05% for nitrate and 0.03–0.09 % for ammonium fertilizer.