How many days after dung produce methane gas?

There is no set answer. All decaying material produces some methane. More in anaerobic conditions. Since everything alive ultimately dies and decays, at some point it will produce CO2/CH4. read more

It depends on several factors, however, in the best conditions: 1kg cow dung produces 250g of biogas (methane gas) over 24hrs. (55-65% from the gas is metane, CH 4). read more

The volume of Methane produced is directly proportional to the freshness of the dung. If the dung is left on ground for months and then fed to the digest chamber of the biogas plant, it’d generate way lesser amount of Methane. read more