Environmental research

EXECUTIVE SUMMARY The operation of a dairy farm in Mauritius will be beneficial for the product of fresh milk for local supply and hence reduce dependence on importation. The Petit Merlo farm intends to start with 50 cows initially, to reach 400 cows within 7 years with a yearly production of 1.2M litres of milk in year 7. The project is in line with the objective of the government to increase our self-sufficiency from the actual two percent, corresponding 3.2M litres to twelve percent in 2015( Blueprint for a Sustainable Diversified Agri Food Strategy for Mauritius (2008-2015). The milk production from January to June 2008 was 1,750,000 litres (CSO, Economic and Social Indicators 2008). However, it will lead to the production of solid and liquid wastes that requires proper treatment and disposal. Traditional practices mainly relied on the agronomic use of dairy wastes which include storage and spreading in the fields and use of the liquid effluent for irrigation for crop production. Although these methods are highly effective in nutrients recycling, it has been reported as being objectionable in terms of odour and to cause nitrates pollution of underground water and water bodies. Furthermore, the dairy farm proposed by the cooperative is situated in proximity to a water table. Hence, the management of wastes, be it solid or liquid is of crucial importance to avoid contamination, which is irreversible. This project will ensure adequate protection through the composting and biogas treatment of the dairy wastes. Another major pollution from dairy farms is the emission of methane. A review of agricultural emission data shows that the majority of CH4 from dairy farms is created through enteric fermentation, followed by emissions from manure storages. In fact, it is believed that 63% are from enteric fermentation and 30% from manure storages (Energy Information Administration, 2006). The intergovernmental Panel on Climate Change (IPCC, 2007) reported that it is extremely likely (i.e representing a 95% confidence interval or higher) that anthropogenic emissions of greenhouse gases (GHGs) are causing a change in global climate. Although many mitigation plans currently focus on reducing carbon dioxide (CO2) emissions, methane (CH4) is a stronger greenhouse gas and has a global warming potential around 23 times that of CO2 (IPCC, 2007). The Food and Agriculture Organisation of the United Nations has claimed that livestock emit more CH4 in CO2 equivalents than is emitted through the burning of fossil fuels for transportation (FAO, 2006). Hence it is important that all efforts be done to quantify and reduce CH4 emissions from livestock. There are several sources of emissions of CH4 from dairy farms; the main ones are from enteric fermentation in the animals and microbial processes in deposited manure. In addition to these major sources, less significant emissions result from field-applied manure and from manure deposited by animals inside the barns or on pasture. Field-applied slurry can result in significant emissions for a few days after application (Chadwick and Pain, 1997; Sherlock et al. 2002). A study by Sedorovich et al. (2008) used the Integrated Farm System Model to simulate a 100-cow dairy farm in Pennsylvania, and the model predicted a total average annual emission of 20 Mg CH4. This included an average annual emission of 135 kg CH4 per cow from the Holstein herd and an average emission of 5.4 kg CH4 per m3 of stored slurry manure. Objectives of proposed project This project has as objective to design the solid and liquid wastes management facility with a view of preventing environmental pollution as well as recovery of useful resources such as compost and feed material for the generation of heat and electricity. It will comprise of two parts. The initial part will involve the design and operation of a solid waste composting plant, further to separation of the liquid and solid fractions. With time, as the number cows is increased from 50 to 400, the amount of wastes generated will become more significant and will justify construction of an anaerobic digester. Hence, in the second part, the design of an anaerobic digester, the composting plant for stabilising the digested cake (which contains less decomposable organic matter) and the recovery, purification and conversion of the biogas to electricity will be considered. Organisation The NGO is a cooperative society (Petit Merlot Farm Cooperative Society Ltd) regrouping 6 dairy keepers. It is specialised in the rearing of cows for the production of milk. Suitability of project The project seeks to address key environmental concerns related to cow farming, namely land contamination, odour and greenhouse gas emissions and ground and surface water pollution. The use of composted manure will serve to enrich the land for growing of grass for fodder, and reduce use of chemical fertilisers. In addition, the use of compost will support organic farming and possibly enable production of organic milk. It is thus in line with the focal areas of the GEF s operational programme No.10 for International Waters (Contaminant-based program), as well as under the focal area of GEF s operational programme No. 6 for Climate change; and under the GEF/SGP category of demonstration and capacity building. The project is also in accordance with the`Maurice Ile Durable` project which aims to reduce the country`s dependence on petroleum fuel, and hence increasing the use of rene

Mauritius