Novel seedling substrate made by different types of biogas residues: Feasibility, carbon emission reduction and economic benefit potential

High-value utilization of biogas residue is essential to drive the development of the biogas industry. This study investigated the feasibility of total or partial replacement for peat (100%, 75%, 50%, 25% and 0%) by corn straw biogas residue and dairy manure biogas residue in growth media for tomato and pepper seedlings. The experiment was arranged in a completely-randomized design, tomato and pepper seeds were sown into each media and grown under commercial nursery conditions until they reached commercial transplant size. The results showed that growth of tomato and pepper was reduced in media containing corn straw biogas residue. However, tomato and pepper seedlings growing in a media of 50% dairy manure biogas residue were considered to be the most satisfactory. The results of the bacterial community analysis showed that the highest abundance of Anaerolineaceae was found in CS100 that meaning immaturity. Furthermore, for a biogas plant with a daily biogas production of 10,000 m3, biogas energy utilization and biogas residue substitution for peat could reduce 439,437 kg/year of CO2 equivalent emissions and arouse 3300,000￥benefit per year by replacing peat. Thus, partial replacement of peat by dairy manure biogas residue as a growth media could be promoted for its wide environmental and economic benefits.