In this book: CO2 Sequestration, Biofuels and Depollution
(www.springer.com/us/book/9783319119052)

the second chapter (by myself and co-authors) is a long review on:

Greenhouse Gas from Organic Waste Composting: Emissions and Measurement

The main conclusions are:

GHG (greenhouse gases) from composting are an important issue for research and for improvement in
real-scale composting facilities. From this review, it is evident that now GHG can
be accounted, measured and properly characterized. However, it is clear that the
disparities of emissions factors for the different GHG that can be found in scientific
literature are due to several factors:

1. The diversity of wastes and technologies used for the composting of organic
wastes.
2. The absence of a consensus in the way to measure GHG, especially in open systems,
where the flow is not controlled.
3. There is wide margin to minimize the GHG emissions from composting, by
changing or updating the current facilities and by improving the performance of
the treatment technologies.
4. The beneficial uses of compost must be also investigated, since it is not clear if
the GHG emitted during the process are compensated by this compost utilization
in the long term.
5. From a Life Cycle Assessment perspective, it is necessary to have experimental
data both on the GHG emissions and the efficiency of the process, to have a fair
evaluation of the environmental impacts of composting.
Further research is necessary to solve these limitations and to provide reliable emissions
factors for composting processes and, in general, for any biological technology
for waste treatment.