Vermiculture in Egypt: - FAO - Regional Office for the Near East and

7. Current on-farm and urban organic waste management practices
and environmental effects of those practices, e.g. carbon and methane
emissions.
The main beneficiaries of this work are the agriculture producers in general and
organic farming producers specifically. Previous chapters covered all aspects of
production of vermicompost and vermiculture. As an organic grower interest, the
environmental positive impacts of utilizing such methods of production, it is
important to understand how vermicompost contribute to improve reducing the
production of greenhouse gases, and consequently help mitigating the global
warming. This chapter aims at highlighting on-farm and urban organic waste
management practices and the environmental effects of those practices.
7.1. Emissions from vermicompost
Composting has been identified as an important source of CH4 and N2O. With
increasing divergence of biodegradable waste from landfill into the composting
sector, it is important to quantify emissions of CH4 and N2O from all forms of
composting and from all stages. The study focused on the final phase of a two stage
composting process and compared the generation and emission of CH4 and N2O
associated with two differing composting methods: mechanically turned windrow and
vermicomposting. The mechanically turned windrow system was characterized by
emissions of CH4 and to a much lesser extent N2O. However, the vermicomposting
system emitted significant fluxes of N2O and only traces amounts of CH4. High N2O
emission rates from vermicomposting were ascribed to strongly nitrifying conditions
in the processing beds combined with the presence of de-nitrifying bacteria within the
worm gut (Hobson et al., 2005).
Different other reports from several countries stated that any possible emissions of
greenhouse gases by earthworms from soil or vermicomposting systems is extremely
small when compared with the well-documented emissions of nitrous oxide, methane
and carbon dioxide from inorganic fertilizer manufacture, landfills, manure heaps,
lagoons, crop residues in soils and manure from pigs and cattle in housed systems.
While there will be N2O emissions from all these sources, there is no justification for
suggesting that environmentally-friendly and energy-efficient systems for producing
vermicomposts and composts should be restricted because of their potential to
produce greenhouse gases. The global production of nitrogenous greenhouse gases in
agriculture should be compared from all sources before vermicomposting is publicly
condemned in such a sensational way (Edwards, 2008).
Recent research has shown that certain types of vermicomposting can generate
significant amounts of N2O. These initial findings indicate a need for more research to
be conducted before any sound recommendations on vermicomposting can be given.
Since the amount of emissions from composting depends on the specific composting
method used and on how well the process is managed, it is not possible to give a
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