The feasibility of an open chamber technique for measuring CH[4] emissions from farm scale pig slurry (PS) and pig solid manure (PSM) storages was examined. Emission rates were over-estimated considerably when the ratio between the area of the inlet and outlet ports was below 5 and 8 for chambers operated on PS and PSM, respectively. A first-order equation describing the chamber ventilation rate necessary to obtain steady state conditions showed high correlation with experimental data. For ventilation rates of 2-3 cm min[-1] steady state was established after 40-54 min. The CH[4] emission from PS was controlled by the transfer resistance in the liquid phase leading to a low effect of wind speed