Instrumental Odour Monitoring Systems (IOMS) are employed for continuous objectified technical olfaction. However, the reference for odour perception is the human nose, surpassing technology with outstanding sensitivity and selectivity for many compounds. In order to achieve comparable results, IOMS have to fulfil manifold requirements, resulting in considerable effort in engineering and cost. One-size-fits-all solutions are unlikely to function properly but are nevertheless marketed as the resulting performance is difficult to assess.

   In the course of the publicly funded research project SEPEG (sensor networks for the objective perception of odour sources, BMBF FKZ 01IS17087) all aspects of a complete IOMS solution are scrutinized in their respective context. A main focus of the project is on field test evaluation in real installation situations. Two installation sites have been equipped with networks of real-time IOMS devices.

   Nitrogen is used in agriculture to fertilise croplands. During the spreading of fertilisers, a substantial part of Nitrogen is lost by volatilisation of ammonia (NH3). These emissions are responsible for unpleasant odours but are also mainly precursors of particulate matters (PM). In Europe, agriculture is one of the main source of nitrogen-composed PM. There is a need to collect more emissions data to understand better this activity impact.

   Measurement techniques of NH3, used for ambient air quality monitoring, are expensive and heavy to manage for the agricultural sector. Other techniques less expensive, like passive sampling, are also used to estimate ammonia flow, but these devices are not adapted for continuous monitoring. For this reason, we decided to customise a common e-nose device to detect ammonia emissions from fertilised grasslands. The sensor array was built using six commercial metal oxide semiconductor sensors. The sensors were inserted radially and evenly into a small size cylindrical PTFE chamber. Four of the selected sensors were sensitive to ammonia, one was sensitive to VOC and the last one was for combustible gas.