We can often see in agricultural plants that the upper layers of silage are visibly different from the layers below them. The goal of the work was to submit evidence that in different depths under the cover sheet, the silage has different quality and different aerobic stability. In the depth of 15 cm, the average temperature was 19.1°C and the pressure 0.9 mPa; in the depth of 45 cm, the temperature was 20.3°C and the pressure 1.32 mPa. In the depth of 0 to 15 cm, the dry matter was 36.3 % and the contents of starch 34.2 % in dry matter; in the depth of 16 to 45 cm, the dry matter was 34.0 % and the contents of starch 36.3 % in dry matter. When measuring the aerobic stability, it turned out that in the silage from the depth of 0 to 15 cm, the temperature rose by less than 2°C, as compared to the laboratory temperature, during whole 5 days of measurement. In the silage from the depth of 16 to 30 cm, the temperature rose by 2°C in 56 hours; in the silage from the depth of 31 to 45 cm in 78 hours. The study shows that the closer to the surface the silage is, the lower is its quality; it contains less nutrients needed for the development of microorganisms.