First results of tall tower based nitrous oxide flux monitoring over an agricultural region in Central Europe

Nitrous oxide is one of the atmospheric greenhouse gases whose amount is significantly influenced by human activity. Its major anthropogenic sources are the agricultural soils but the emission is known only with large uncertainty yet. The paper presents a tall tower based measuring system installed in Hungary, which is designed for the long-term monitoring of nitrous oxide emission of a regionally typical composition of agricultural fields by means of eddy covariance technique. Due to the careful calibration of the gas analyzer applied the measuring system is also suitable for the recording of the atmospheric concentration of nitrous oxide on the globally compatible scale (WMO X2006A). The paper reports the results of the first two years of the monitoring program, which is the first of its kind in Central Europe. For the period of July 2015-June 2017 the concentration measurements indicate an increasing trend of 0.91 nmol mol−1 year−1 with an average concentration of 330.64 nmol mol−1. During the two years of the project, the monitoring system recorded a total of 441 ± 195 mg N2O-N m−2 nitrous oxide emission with late spring/early summer maximum. The measurements also revealed the episodic nature of the emission typically triggered by major precipitation events.