Apr 15, 2020 · When the ratio of cattle manure to sludge is 2:1, the methane content will be stable between 45 and 51.4% in the first 130 days, and then slowly decrease. When the ratio of cattle manure to sludge is 3:1, the methane content will rise slowly in the first 120 days, and reach the maximum value of 55% on the 140th day, and then keep stable.