ENVIRONMENTAL SYSTEM ANALYSIS FOR HORTICULTURAL CROP PRODUCTION

Abstract

In this paper a simplified Life Cycle Assessment for the evaluation of environmental impacts of horticultural production systems is presented. Two production systems with different production intensities (outdoor cropping, protected cultivation in a greenhouse) have been investigated with respect to the environmental impact associated with these production systems. In the open field production system the transport processes on-field and field-to-farm are contributing most to the environmental impact. In closed greenhouse production systems the lighting and heating processes are dominating the environmental impact. The system analysis performed in this study allows for the identification of those process steps in horticultural production that are major contributors to environmental impact. Therefore, the results can help the growers to improve the environmental performance of their production system. INTRODUCTION During the last years, there has been an increasing public concern regarding food safety and quality as well as regarding the environmental risks and impacts associated with agricultural or horticultural production processes. In the future the growers are expected to report on the environmental impacts of their production systems and activities. While maintaining the productivity of their production systems, they simultaneously need to reduce environmental impacts. The traditional crop production strategies were concentrated on the single criterion of maximum production. Modern crop production systems must take into account the environmental impacts as well. Due to these more consumeroriented strategies the interpretation of quality is changing. In addition to the product quality the process quality, and in particular the environmental impacts associated with the production processes, becomes more and more important. However process quality standards are not established yet and for an implementation of such standards it is necessary to obtain detailed information about the processes and the associated environmental impacts. PROCESS QUALITY EVALUATION Life Cycle Assessment (LCA) is a suitable technique for assessing environmental aspects and potential impacts associated with a product or a process. A LCA study is a standardized methodology where all extractions from the environment and emissions to the environment are determined, if possible in a quantitative way. LCA regards the whole life cycle of a process or a product from cradle to grave and assesses the potential impacts on natural resources, on natural environment and on human health accordingly (de Haes and Wrisberg, 1997). The methodology has proven to be a useful tool to trace environmental impacts and to improve the environmental performance of production systems by quantifying the relevant impacts according to single process steps (Schlauderer et. al. 2002). AIM OF THE RESEARCH In this study two production systems of practical vegetable growers with different production intensities (outdoor cropping of bunched onions and radish, protected Proc. XXVI IHC – Sustainability of Horticultural Systems Eds. L. Bertschinger and J.D. Anderson Acta Hort. 638, ISHS 2004 Publication supported by Can. Int. Dev. Agency (CIDA) 70 cultivation of tomatoes in a greenhouse) have been investigated in order to study the environmental impacts associated with these production systems. For the evaluation of environmental impact a simplified life cycle assessment approach has been used. Such a system analysis should help to identify major contributors to the environmental impact and to find opportunities to improve the environmental aspects of products or processes. EVALUATION OF THE ENVIRONMENTAL IMPACTS One of the first steps in such a Life Cycle Assessment is the Life Cycle Inventory Analysis (LCIA), where the relevant inputs and outputs have to be determined for all the different production steps. Unit process steps have to be defined for the whole production chain that represent the smallest portions of a product system for which data are collected (ISO, 1997). In table 1 the analyzed production systems, the unit processes, the system boundaries and the data sources analyzed in this study are summarized. For an evaluation of these production systems with different production intensities, different environmental impacts as well as different functional units (production area, yield, volume of sales) have to be taken into account. The environmental impact is divided into different impact categories, like cumulative primary energy demand, global warming potential, ozone depletion, etc. The functional units are the basis to which the impact of a product or a process is related to. In the impact assessment phase, the detailed data collected in the inventory are assigned to the environmental impact categories. Every input and output defined in the LCIA is placed into one or more impact categories. Then the potential environmental impacts associated with each unit process is calculated. Therefore each input and output in the LCIA is placed into one or more impact categories. In study presented, the two impact categories ‘cumulative primary energy demand’ and the ‘global warming potential’ were considered initially. RESULTS A LCA allows for the identification of weak points of an entire production system. In the LCA performed in this study, major contributors to the different environmental impact categories could be identified. A weak point analysis for the investigated outdoor cropping system is shown in figures 1 and 2. The environmental impact can be assigned to the demand of resources (material or energy), to different process steps, and to the different products. During the cultivation of bunched onions the highest environmental impact expressed as cumulative primary energy demand is caused by field-farm transport processes in form of fuel consumption. With regard to material consumption, however, the process steps of fertilizing and plant protection cause the major contribution due to fertilizer and pesticide production. Additional demand for material by machinery and tractors are of minor importance. Therefore, there is a great potential for increasing the ecological efficiency by optimizing the transport system. In figure 3 the influence of the selected functional unit on the results is illustrated. For the area as the functional unit, bunched onions have a higher environmental impact than radish. On the other hand, considering the environmental impact in relation to the yield (presented as 10.000 bunches), figure 3 reveals a higher impact of radish compared to bunched onion. This higher environmental impact of radish is even more pronounced with respect to the volume of sales as the functional unit. These results show that an evaluation of the environmental impacts strongly depends on the selected functional unit. For an objective evaluation of the environmental impacts that are related with a chosen production system, several functional units have to be taken into account. The choice of the functional unit depends also on the interested parties. E.g. the environmental impact related to a specific area could be relevant to governmental authorities, while consumers might be more interested in a relation of this impact to the product itself. As shown in figure 4, in the greenhouse production system a large portion of the environmental impact is related to the greenhouse material itself. In comparison to the