Introduction
The agricultural sector is the source of major environmental contamination. Recent studies conducted in the US have shown that the agricultural sector is responsible for 6.4% of greenhouse gas emissions. Because of its closer ties to the environment than other sectors of the economy, as well as because of the extensive use of chemical fertilizers and other chemicals like pesticides, agriculture is regarded as one of the major sources of environmental pollution. The extensive use of chemical pesticides and fertilizers, as well as the absence of suitable and workable techniques for the best possible use of chemical fertilizers, are the main causes of the pollution produced by agricultural activities. It has been determined that the energy consumption and greenhouse gas emissions of the food production system vary greatly between its sectors. Along the production chain, there are good chances to lessen environmental impacts. Food production requires an understanding of energy consumption and emissions of pollutants. However, there aren't many publications comparing and analyzing the life cycle assessment of outdoor and greenhouse tomato growing. The environmental impacts of cultivating tomatoes in two different types of greenhouses and open field cultivation are thus compared using life cycle assessment (LCA) in Nahavand city in accordance with the significance of LCA evaluation in this study.
 
Material and Methods
In Nahavand City, greenhouses and open-field cultivation were used to gather the data required for tomato output in a single growing season. Information was gathered for this study via questionnaires, interviews, document and library investigations, and database utilization. The life cycle assessment approach was used in this study to analyze the effect categories using consumption inputs, such as diesel fuel, nitrogen, potash, and phosphate fertilizers, as well as animal manures (cow, sheep, and chicken). After sorting and categorizing, the data was entered into the Sima Pro version 9.1 program to assess the environmental effects of tomatoes. The assessments were conducted using the Impact2002 technique, and the results were calculated based on specific units.
 
Results and Discussion
With a general review of the inputs for the production of tomato products in both open field and greenhouse cultivation, it can be found that in  open field cultivation, nitrogen fertilizer has the largest share on 5 environmental indicators, including Global warming, Aquatic acidification, Terrestrial acid/nutri, Aquatic ecotoxicity and non-carcinogenic is one of the most important inputs affecting environmental indicators. To control and reduce the above indicators, it is possible to reduce them by reducing the use of nitrogen fertilizers. In greenhouse cultivation, Nitrogen fertilizer has had the largest share on 3 environmental indicators.After nitrogen fertilizer, diesel fuel is another important input in influencing environmental indicators. In greenhouse cultivation, diesel fuel has the largest share on 4 environmental indicators, including Aquatic eutrophication, Ozone layer depletion, non-renewable energy and Ionizing radiation, and in open cultivation, it has the largest share on 3 ozone layer environmental indicators. By replacing old tractors with new tractors, the emission of NOX and SOX pollutants caused by the combustion of diesel fuel can be reduced and the resulting environmental effects can be reduced. In the other part, the results of the study revealed that the highest amount of environmental destruction was due to fertilizers and the consumption of diesel fuel for the operation of machinery, which caused more destruction.
 
Conclusions
This research was conducted in order to evaluate the life cycle assessment of tomato production in open field and greenhouse cultivation, using Sima Pro software. The results showed that greenhouse cultivation has more environmental effects compared to open field cultivation. Nitrogen fertilizer and diesel fuel used in the production systems had the greatest impact on the environmental indicators. By replacing old tractors with new tractors, the emission of NO_X and SO_X pollutants caused by the combustion of diesel fuel can be reduced and the resulting environmental effects can be reduced. Also, reducing the use of chemical fertilizers, especially nitrogen fertilizers and pesticides will improve the environmental effects of tomato production. Improving the environmental performance of tomato production in open field or replacing it with greenhouse production should be considered.