Environmental system analysis of tomato production in Ghana
Tomato (Lycoperscicum lycopersicum) production in Ghana is characterised by low yields and high fertiliser input. This is compounded in the long run by production shocks due to environmental pressures such as drought, pests and diseases. Tomatoes among other vegetables are more susceptible to these biotic constraints than other crops. Chemical pesticides and, to a limited extent, integrated pest management practices have been applied to control the pests and diseases but with limited success. Pesticides use has been ineffective, leading farmers to apply high dosages. The aim of this study was to identify the most important sources of greenhouse gases, acidifying and eutrophying compounds associated with tomato production in Ghana and identify options to reduce the environmental impacts. Life Cycle Analysis (LCA) methodology was used in the analysis (Cradle to gate approach). The inventory analysis involved collection of data on raw material, energy consumption and emissions. From the results, it was revealed that approximately 8,544 kg CO2-equivalents of greenhouse gas was emitted per hectare of tomato production in Ghana. Among the three main components of greenhouse gases, CO2, CH4 and N2O, N2O accounted for the highest value followed by CO2. When we considered the activities that generated greenhouse gases, fertiliser application ranks the first with a share of 97%. The total hectare acidifying emissions from SO2 and NOX were calculated to be 19.50 kg SO2–equivalent. When we considered the result in terms of actual and SO2 equivalent, emission of NOX was larger than that of SO2. About 211.50 kg PO4 equivalent of eutrophying compounds was found to be discharged per hectares. With regards to options to reduce environmental impact of tomato production in Ghana, practices that recover investment cost and generate a profit in the short term are preferred over practices that require a long term to recover investment costs: practices that have a high probability associated with expected profits are desired over practices that have less certainty about their returns.