The highest cumulative biogas yield for 60-day digestion was obtained in B group, which was 23.2%
higher than that of A group, 29.1% higher than H group and also 40.7% higher than I group. The result
indicates the biogas yield of anaerobic digestion of the pretreated corn stover mixed with cow dung is
higher than that of the untreated ones mixed with cow dung, and higher than that of the untreated ones
alone, also higher than the cow dung alone. The biogas yield of the pretreated corn stover mixed with
cow is higher than the pretreated ones with the sludge.