Agronomic management strategies for optimising biogas yield in lignocellulosic energy crops

Lignocellulosic energy crops are promising feedstocks for anaerobic digestion, but their biogas potential depends on biomass productivity, composition and digestibility. This systematic review evaluates the effects of agronomic management on biomass production, feedstock quality and biogas/methane yield in lignocellulosic energy crops and identifies key research gaps. A systematic literature search was conducted in the Scopus database for English-language journal articles published from 2005–26, using predefined Boolean terms covering lignocellulosic energy crops, anaerobic digestion/biogas production and agronomic management. Following screening and eligibility assessment, 89 studies were included in the qualitative synthesis. The evidence indicates that nutrient management, irrigation, planting density, harvest timing and frequency and genotype selection strongly influence biomass yield and feedstock characteristics, thereby affecting methane production. Optimised nutrient management can improve biomass productivity and substrate quality, whereas excessive nutrient inputs may reduce nutrient-use efficiency and adversely affect digestion performance. Harvest timing is critical because increasing biomass yield with maturity may be associated with greater lignification and reduced digestibility. Ensiling, pretreatment and co-digestion can further improve feedstock accessibility and methane recovery. However, evidence remains heterogeneous, with limited integration of agronomic performance, methane productivity, environmental impacts and economic feasibility. Future research should prioritise standardised methods, long-term field-to-digester studies and integrated environmental and economic assessments. Overall, coordinated optimisation of agronomic practices and anaerobic digestion is essential for sustainable biomethane production.