LCA of a tomato crop in a multi-tunnel greenhouse in Almeria

Protected crops have expanded significantly in the Mediterranean area over the last few decades as a successful means to provide abundant and high-quality produce. Although resources are generally used efficiently, greenhouse areas cause major environmental impacts. The aim of this work was to study, from an environmental point of view, the improvement capacity of greenhouse areas in the Mediterranean region and to assess several alternative agricultural practices to decrease their contribution to the environmental impacts in this system. The methodology used was life cycle assessment (LCA) based on a tomato crop grown in a multi-tunnel greenhouse in Almeria, on the southeast coast of Spain. The functional unit chosen was 1 ton of loose classic tomatoes. Five midpoint impact categories and one energy flow indicator were selected for their relevance. The agricultural practice alternatives evaluated were reduction of volume of substrate and fertilizers, extension of substrate and greenhouse life span and increase in renewable energy for electricity production. The results indicated that the main contributors to impact categories in the tomato production were structure, auxiliary equipment and fertilizers. Structure accounted for between 30 and 48 % of the contributions, depending on the impact category. The principal burdens in the auxiliary equipment stage were substrate and consumption of electricity. Fertilizers environmental impacts were due to emissions during their manufacture and application to the crop. In a best-case option, taking into account the best alternatives, contributions to the impact categories were reduced by between 17 and 30 %. The LCA methodology proved to be a useful tool to evaluate the environmental damage of this agricultural activity. The importance of including farm infrastructure in the assessment was demonstrated as it was a major contributor. The risk of eutrophication could be reduced by adjustment of the fertilizers-water balance and implementation of a closed-loop irrigation system. Future technological improvements should be developed to increase yields and thereby directly reduce the environmental burdens per unit produce. The present study served to assess the environmental impacts of a tomato crop in a multi-tunnel greenhouse on the coast of Almeria. The assessment was used to evaluate alternatives for improvement of cleaner production in greenhouse areas. Further research should focus on assuring the feasibility of the suggested options.