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

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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 62
definitive answer to the question of how much composting contributes to climate change. Most studies on emissions from composting have been carried out in developed countries where conditions differ from the target countries of this study. Nevertheless, several environmental agencies have concluded that when composting is done properly, it generates very small amounts of greenhouse gases (IGES, 2008). Chan et al. (2010) investigated greenhouse gas emissions from three different home waste treatment methods in Brisbane, Australia. Gas samples were taken monthly from 34 backyard composting bins from January to April 2009. Averaged over the study period, the aerobic composting bins released lower amounts of CH4 (2.2 mg·m - 2 ·h -1 ) than the anaerobic digestion bins (9.5 mg·m -2 ·h -1 ) and the vermicomposting bins (4.8 mg . m -2. h -1 ). The vermicomposting bins had lower N2O emission rates (1.2 mg m -2 h -1 ) than the others (1.5–1.6 mg·m -2 ·h -1 ). Total greenhouse gas emissions including both N2O and CH4 were 463, 504 and 694 mg CO2e m -2 ·h -1 for vermicomposting, aerobic composting and anaerobic digestion, respectively, with N2O contributing >80% in the total budget. The greenhouse gas emissions varied substantially with time and were regulated by temperature, moisture content and the waste properties, indicating the potential to mitigate greenhouse gas emission through proper management of the composting systems. The results suggest that home composting provides an effective and feasible supplementary waste management method to a centralized facility in particular for cities with lower population density such as the Australian cities. In terms of greenhouse gas emissions during the maturation process, the windrow composting process was characterized by emission of CH4. Emission of greenhouse gases from vermicomposting was predominantly N2O with comparatively little CH4 emitted, demonstrating that sufficiently aerobic conditions were maintained in the vermicomposting beds to inhibit CH4 production. The global warming potential of the vermicomposting maturation system was estimated to be approximately 30 times greater than that for the windrow composting system. The emission of greenhouse gases from these types of composting systems requires further investigation. Vermicomposting by worms decreases the proportion of 'anaerobic to aerobic decomposition', resulting in a significant decrease in methane (CH4) and volatile sulfur compounds which are readily emitted from the conventional (microbial) composting process. Vermi-composting of waste organics using earthworms therefore has a distinct advantage over the conventional aerobic composting as it does not allow the greenhouse gas methane (CH4) to be formed. Molecule to molecule, methane is a 20-25 times more powerful greenhouse gas than CO2. Earthworms can play a good part in the strategy of greenhouse gas reduction and mitigation in the disposal of global organic wastes as landfills also emit methane resulting from the slow anaerobic decomposition of waste organics over several years. However, recent research done in Germany has found that earthworms produce a third of nitrous oxide (N20) gases when used for vermicomposting. Molecule to molecule N:0 is a 296 times more powerful greenhouse gas than carbon dioxide (CO2). This needs further study (Daven and Klein, 2008). 63
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Vermiculture in Egypt: Current Deve
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The designations employed and the p
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4.3. Overview of organic waste reco
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List of tables Table 1.1 Major fami
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SF6 Sulphur hexafluoride SWM Solid
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Executive Summary Vermiculture in E
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For three millennia (3,000 years),
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1.3. Types of earthworms Earthworm
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enclosure could not be ascribed wit
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2. Trial of vermiculture and vermic
Page 22 and 23: Table 2.2. Advantages and disadvant
Page 24 and 25: 2.1.3. Moisture The bedding used mu
Page 26 and 27: The growth of E. fetida in organic
Page 28 and 29: 18 Photo 2.3. Commercial vermicompo
Page 30 and 31: 2.3. The trial experience in Egypt
Page 32 and 33: 2.3.4. Moisture Photo 2.9. The loca
Page 34 and 35: - Placing narrow strips of 1-2 day
Page 36 and 37: 3. Use of compost worms globally in
Page 38 and 39: vermicastings produced per crop is
Page 40 and 41: users in Dharwad) and $3.2 per ton
Page 42 and 43: 3.4. Vermicompost „teas‟ in Ohi
Page 44 and 45: 4. Current on-farm and urban organi
Page 46 and 47: The clearly evident symptoms of the
Page 48 and 49: whole; in many cities the municipal
Page 50 and 51: 4.3. Overview of organic waste reco
Page 52 and 53: Table 4.4. Egypt‟s Integrated Sol
Page 54 and 55: Table 4.6. Solid waste amount produ
Page 56 and 57: which needs to find other alternati
Page 58 and 59: The latest fertilizers consumption
Page 60 and 61: 5.3.2. Vermicomposting of agricultu
Page 62 and 63: Table 5.3. Potential nutrients that
Page 64 and 65: demand in the world. Thus earthworm
Page 66 and 67: earthworms, delivering a protein pu
Page 68 and 69: the cost of fish-keeping, but also
Page 70 and 71: aquaculture started to exert some s
Page 74 and 75: 7.2 Total emissions from waste sect
Page 76 and 77: Greenhouse gases Source & Sink Cate
Page 78 and 79: CH4 ; Figure 7.1. Egypt‟s greenho
Page 80 and 81: properties of the treated sludge, t
Page 82 and 83: The United Nations Framework Conven
Page 84 and 85: 2. Abatement of nitrous oxide from
Page 86 and 87: 9. Analysis of the Egyptian context
Page 88 and 89: Table 9.1. Summary of identified mi
Page 90 and 91: References Aldadi, H.; A.R. Parvare
Page 92 and 93: Ghafoor, A.; M. Hassan and Z.H. Alv
Page 94 and 95: Sunitha, ND; R. S. Giraddi,; K. A.
Page 96 and 97: How long will the material ingested
Page 98 and 99: earthworm test species. This specie
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