| Summary: | Nitrous oxide (laughing gas, N<sub>2</sub>O) is a relevant greenhouse gas. Agriculture contributes significantly to its emissions. As nitrogen fertilization has been identified as one of the main sources of N<sub>2</sub>O, controlled application and reduction of the amount of fertilizer adapted to crop demand is essential to reduce N<sub>2</sub>O emissions. This requires detailed studies of the local distribution of the N<sub>2</sub>O emission fluxes on different croplands. Consequently, frequent spatially resolved field measurements of N<sub>2</sub>O concentrations are needed. A precision in the ppb range close to the ambient N<sub>2</sub>O level of 333 ppb is necessary. Tunable laser absorption spectroscopy using quantum-cascade lasers (QCL) as a light source is an established technique for the measurement of N<sub>2</sub>O traces. We present the development and validation of a compact portable setup for on-site measurement of N<sub>2</sub>O emissions from the soil. The setup differs from previous solutions by using an interband cascade laser (ICL), which has significantly lower power consumption compared to a QCL. The portable measurement setup allows N<sub>2</sub>O emission fluxes to be determined with a precision of 3.5% with a measuring duration of 10 min. The developed system enables the detection of increased N<sub>2</sub>O emissions because of the fertilization of fields. High N<sub>2</sub>O emission fluxes are indicators of the overfertilization of the field. Directly after fertilization, N<sub>2</sub>O fluxes between 2.9 and 5.3 µL m<sup>−2</sup> min<sup>−1</sup> depending on the gas acquisition site are measured during the field tests. Over time, the fluxes decrease. The obtained results compare well with data from more precise but also more complex and maintenance-intensive instruments for atmospheric research. With this system, the soil moisture as well as the air humidity and air temperature are recorded. Strong influences on N<sub>2</sub>O fluxes by soil moisture were observed. The presented measurement system is a contribution to the establishment of mobile N<sub>2</sub>O screening systems that are robust in the field and suitable for comprehensive and routine detection of N<sub>2</sub>O emissions from soil.
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