Of the anthropogenic greenhouse gas emission in Denmark animal manure contributes an estimated
40% of methane (CH4) and 20% of nitrous oxide (N2O). Livestock production systems undergo
changes for the purpose of increasing animal welfare, and such changes often include increasing the
amounts of bedding manure. Emission of greenhouse gases from composting pig deep litter was
studied during a 4-month period. Effects of increasing the amount of straw used in deep litter
(reducing litter density) were included in the study. Methane was produced at a high rate in the centre of the heap at high density during the thermophilic phase of composting, and CH4 emission was only measured during this phase. In this treatment N2O was also produced in the centre both initially and after the temperature of the compost had dropped to below 45 A