On the basis of model concepts on physical gas exchange a technique was developed for studying the complex interrelationships existing between the characteristics indicating the suitability of a particular material for ensilage and the specific local conditions for silage making at the farm and in a silo. (degree of anaerobic conditions). Conclusions were drawn as to quantitative relations existing between the thickness of the marginal layers of a silage stack that are subject to losses and the compaction of the silage material and the sealing of the silage top during the periods of filling and storage. On the basis of these considerations limits are given for minimum filling of a silo per day of ensilage as depending on the compactness of the consolidated fresh or wilted silage material. Data are given for silage losses at the edged of the silage stack.