## 3 Results and Discussion  
The results of the temperature measurements are graphically represented in Figures 2 and 3. Figure 2 shows the temperature dynamics of the control without silage additive (treatment CON) and the temperature dynamics in the silage treated with the chemical additive (treatment CHEM). Figure 2 also represents the buckets including silage treated with the biological additives (B1 and B2). Each graph shows the means calculated from the hourly average of the original data of three buckets per variation. At the beginning of the experimental period, a lag time (T0-phase; cf. [15]) of 24 h can be observed in which the temperature of the control does not rise significantly. Afterwards, the temperature starts rising slowly. Therefore, the statistical analyses did not show any significant differences between the temperatures of the sensors in the control in the first 48 h. These findings are consistent with the data shown in Figure 2.  
Figure 3: Means of gas concentrations of samples taken from buckets of the control variation at two sampling points (A and B); CON = control group, HD = high density, LD = low density. Figure 2: Temperature means per sensor, obtained from hourly average of temperature data measured in different treatments; CON = control group, CHEM = silage treated with the chemical additive, B1 = silage treated with biological additive 1, B2 = silage treated with biological additive 2, HD = high density, LD=low density. Figure 3 graphically visualises the gas concentrations and shows that there is nearly no oxygen inside the untreated silage at the time of opening, but the CO\({}_{2}\) content is much higher than in the surrounding air. After opening, O\({}_{2}\) diffused into the buckets during the T0-phase while CO\({}_{2}\) flowed out. When the temperature started rising at the beginning of the T1-phase, 24 h after opening (cf. [15]), the oxygen content of the buckets decreased. This fact underlines that microorganisms start to change their metabolism and use oxygen as a direct response to an anaerobic phase. Once they have changed their metabolism from anaerobic to aerobic, the oxygen is consumed by microbial respiration, which is accompanied by a temperature rise. The low-density variation of treatment CON became significantly warmer than the high-density variation. Figure 3 shows that oxygen diffused into the low-density buckets much faster than into the high-density buckets. The maximum O\({}_{2}\)-Konzentration in the lower part of the LD buckets of treatment CON is reached after 14 h, whereas the maximum O\({}_{2}\) concentration in the lower part of the HD buckets of treatment CON is reached after 60 h. This can be reasoned by the fact that the low-density buckets include a much higher void volume holding a higher capacity for entering gas. In contrast to this, the higher density of the HD buckets represents a stronger barrier against incoming air. [PERSON] et al. [17], observed a longer period of aerobic stability in mechanically-processed corn silages compared to unprocessed variations. They justify this finding by the fact that the processed variation has a greater wet pack density and, therefore, excludes oxygen. These findings are consistent with the findings at hand. As the data of treatment CON shows, sensor 1 measured higher temperatures than sensor 2 which, in turn, measured higher temperatures than sensor 3 in the HD and LD variation. These results underline previous findings by [PERSON] et al. [15] and Figure 3 shows the reason for this fact: less oxygen is reaching the deeper parts of the buckets (sampling point B) than the parts of the silo directly near the face. Additionally, more CO\({}_{2}\) accumulates in the deeper silo areas. This is underlined by the results of the statistical analysis which showed the temperature measured by sensor 1 to be higher (\(p<0.001\)) than the temperature measured by sensors 2 and 3 in the HD variation during the period beginning in hour 48 of the experiment.