MEASUREMENT OF AMMONIA EMISSIONS AFTER LIQUID MANURE APPLICATION .1. CONSTRUCTION OF A WINDTUNNEL SYSTEM FOR MEASUREMENTS UNDER FIELD CONDITIONS

A windtunnel system is presented applicable for measuring ammonia emissions under field conditions. With this system two objectives are achieved: 1. No alteration of the microclimatic conditions in the testing area 2. Reliable determination of the volumetric air flow and the ammonia concentration The use of a transparent foil, the precise adjustment of the flow velocity to the windspeed outside, and the constant cross-sectional area over the whole length of the tunnel are the most important constructional details of the system.