Analysis of the Process of Applying Molasses to Grass and Clover Green Fodder in Terms of Silage Quality for Biogas Plants

Silage used in biogas production is one of the main sources of substrate for anaerobic digestion in agricultural biogas plants. However, it is advisable to use plants with high dry matter and sugars content, which can increase biogas efficiency. The study aimed to analyze the effect of selected parameters of the molasses application process to green fodder during its harvesting with a compacting baler on the quality of the obtained haylage. Molasses was applied during the harvesting of semi-dried green fodder in the following variants: before the pick-up and after the pick-up of the round baler in the amount of 5% dry matter. The ensiled raw material was a mixture of red clover and perennial ryegrass, which was characterized by an average dry matter content of 65%. The lowest coefficient of variation of reducing sugar content was found in silage from shredded plants with molasses applied before the cutting unit, which is 27.5%. The bales of green fodder obtained from whole and shredded plants with molasses applied before the cutting unit had the highest average reducing sugars content, respectively: 9.65 g·dm-3 and 9.24 g·dm-3. The quality of haylage was assessed based on the Flieg–Zimmer scale. All analyzed fodders received the maximum number of points and were classified as very good. The highest lactic acid content in the amount of 54.66 g·kg-1d.m was found in haylage from shredded plants with molasses applied before the cutting unit. The pH value of the assessed fodders ranged from 5.43 to 5.53 and was characteristic of preserved fodders with a dry matter content of over 600 g·kg-1d.m. It was found that both the fragmentation of plants and the place of application of molasses to the green forage during harvesting with a round baler affect the amount and distribution of molasses in the bale and the lactic acid content in the haylage.