Enhancing Grass and Maize Silage: Role of Silage Additives and Environmental Implications for Biogas Production

Silage additives enhance forage preservation and resource efficiency by reducing dry matter (DM) losses and limiting aerobic spoilage. This study evaluated crop-specific lactic acid bacteria (LAB) inoculants by comparing treated (T) silage with untreated (U) controls for maize and grass. Silage quality was assessed using nutritional, fermentation, and microbial indicators, alongside aerobic stability (ASTA) and biogas yield. Additionally, a carbon footprint (CF) assessment, based on primary data from a farm in northern Germany with background datasets, quantified the implications for the biogas-to-electricity pathway. Two scenarios were modelled, with Scenario II accounting for changes in soil organic carbon (SOC). LAB additives improved preservation, with DM losses decreased from 18.48% in untreated grass (UG) to 13.17% in treated grass (TG) and from 21.53% in untreated maize (UM) to 5.21% in treated maize (TM). ASTA increased to 223 h for TM and 218 h for TG, alongside a lower presence of yeasts and moulds. In Scenario I, CF decreased by 5.00% for TG (293.53 g CO2-eq kWhel−1) and 6.89% for TM (229.05 g CO2-eq kWhel−1). Under Scenario II (including SOC), TG showed a value of 135.43 g CO2-eq kWhel−1, and TM 321.48 g CO2-eq kWhel−1. Overall, the additive improved silage stability and reduced climate impacts.