Biogas fermentation from the biological conversion of
livestock manure has received increasing attention as a
renewable source of energy (Andara and Esteban, 2002). It
is also becoming a renewable green energy trend in the development
of stockbreeding in China. Biogas residue (BR),
the solid material remaining after biogas production, is a
byproduct of the fermentation that can be used as organic
fertilizer, which can not only improve soil fertilization, but
also improve crop biomass and quality