Biogas yielding potential of sorghum as affected by hybrid and plant density

Abstract

Biogas production from crop biomass is a promising renewable energy source, whose importance has increased in northern European countries through the use of maize. Sorghum crop, however, offers great morphological diversity including traits such as Brown Mid Rib (BMR), stay-green, dry pith, high sugar content. All these traits are associated with high biomass yields that can potentially be used for biogas production while remaining compatible with food security. This experiment aimed to estimate the biogas and methane production potential of three sorghum biotypes under two contrasting planting densities. The results showed significant effects of hybrid on all variables studied. No significant interaction between Hybrid × Density was detected for any of the variables mentioned, except for total soluble solids, so the performance of hybrids was averaged across densities for most traits. Both the conventional photosensitive morphotype and the silage type showed the best performance in biomass yield, which positively influenced the potential yield of biogas and methane. The BMR morphotype and maize recorded the highest values for specific biogas (Y_B) and methane yields, partly due to their low lignin content and high grain proportion. A significant positive association was found between NDF digestibility and Y_B. Based on the results, it is concluded that sorghum is an excellent alternative for biogas and methane production, capable of successfully complementing maize crop.