An ammonia and greenhouse gases production of dairy cows on pasture is impossible to determine. On this account has been realized a equipment in which can be simulate ammonia and further gases release into atmosphere. Subject matter of an invention is a measuring tunnel and ventilation fan with possibility cotroled of flow rate. Like gases emission source in the measuring tunnel are 4 excretion cakes with exactly defined parameters, with total weight c.16 kg. In front of air outlet from the tunnel are located the gases sensors. During experiment time can be model except the flow rate a rainfall quantity, mechanical intervention into excretion cakes integrity, pasture harrowing and other interventions.