Evaluation of the sustainability of four greenhouse vegetable production ecosystems based on an analysis of emergy and social characteristics

The use of emergy to evaluate the sustainability of greenhouse systems leads to management recommendations to increase the sustainability of production in these systems. In this study, four greenhouse systems for cucumber, tomato, bell pepper, and eggplant production, located in Jiroft city, Iran, were evaluated using emergy sustainability indices. To accomplish this study, 56, 31, 19, and 12 greenhouses were selected for cucumber, tomato, bell pepper, and eggplant production, respectively. Analysis of twelve emergy indices and a study of the social characteristics of the producers using Analytic Hierarchy Analysis showed that the sustainability of the cucumber production system was greater than that of the other three systems. The calculated unit emergy values for economic yield (UEVE) generally indicated that greenhouse systems were at least 100 times more sustainable than open farm systems for the production of different products, primarily because of drastically reduced soil erosion. The highest (5.10E+04 sej J(-1) [4.96E+04, 5.25E+04]) and lowest (7.27E+03 sej J(-1) [7.09E+03, 7.45E+03]) UEVE values were calculated for the bell pepper and cucumber systems, respectively. Also, cucumber producers had greenhouses with larger areas compared to the greenhouses used for the other crops examined in this study. The physiological characteristics of cucumber plants resulted in greater sustainability of this system, because the plants were able to capture more of the free renewable energy, had a higher production potential, and this production system made more efficient use of the workforce. In contrast, the highest proportion of purchased non-renewable resources reduced the sustainability of the eggplant production system compared to the other systems studied. Therefore, selection of a plant with more potential to use free local environmental energy, higher yield, and more efficient use of labor will lead to greater sustainability of greenhouse vegetable production systems. Sustainability can also be increased by paying attention to the sociotechnical characteristics of the producers, the use of technologies to reduce non-renewable inputs to the greenhouse building, and by reducing the proportion of non-renewable inputs used overall.