The Comprehensive Environmental Impact Analysis of Greenhouse and Open-Field Cucumber Cultivation Using Life Cycle Assessment in Hamedan-Bahar Plain: A Practical Comparison

Introduction
The production of fresh vegetables like cucumbers, especially in regions with climatic constraints during certain seasons, plays a crucial role in food security, nutritional health, and the agricultural economy. In Iran and many temperate or cold climate areas, the use of greenhouse systems has been increasing as a method for off-season production with high yield. However, productivity should not be the sole criterion for selecting a cultivation method, as energy, water, fertilizer, plastic, and other inputs in greenhouses can lead to significant environmental impacts if not managed properly. Therefore, a comprehensive environmental assessment of the cucumber production chain, from input supply to harvesting and packaging, is essential for sustainable production decision-making.
 
Material and Methods
This study investigates the environmental impacts of cucumber cultivation using two agricultural systems: greenhouse and open-field, through a Life Cycle Assessment (LCA) approach. The research was conducted in the Hamedan-Bahar plain, utilizing local field data. The study area spans 2,459 square kilometers, with approximately 32,100 hectares dedicated to irrigated agriculture. Data were gathered through surveys and interviews with local farmers, and relevant literature was reviewed to support the research. LCA methodology was employed to model the environmental effects of cucumber production from raw material extraction to waste management, using the SIMAPRO software. The impacts of various inputs, such as chemical fertilizers, energy, pesticides, and fuel consumption, were calculated, and the environmental effects were assessed based on global warming potential (GWP), ozone depletion, and other environmental indicators.
 
Results and Discussion
The results of the study revealed significant differences in the resource consumption and environmental impacts between the greenhouse and open-field cucumber cultivation systems. Specifically, greenhouse cultivation exhibited higher consumption of inputs such as electricity (1072.2 kWh per ton in greenhouses vs. 320 kWh in open fields) and diesel fuel (1.63 liters per ton in greenhouses vs. 2.9 liters in open fields). Additionally, nitrogen fertilizer use in greenhouses was higher (6 kg per ton in greenhouses vs. 3 kg in open fields), as well as manure consumption (900 kg per ton in greenhouses vs. 154 kg in open fields). From an environmental perspective, greenhouse cultivation showed a significantly higher impact in various categories. For example, the global warming potential (GWP) for one ton of cucumbers was 111 grams of CO₂ equivalent in greenhouses, compared to only 95.1 grams of CO₂ equivalent in open-field cultivation. Greenhouses also exhibited higher contributions to ozone layer depletion and other environmental indicators. The findings indicate that while greenhouse cultivation provides better control over environmental conditions and higher yields, it leads to greater environmental burdens due to higher energy and chemical inputs. In contrast, open-field cultivation, though less efficient in terms of yield, results in lower environmental impacts, particularly in terms of energy consumption and fertilizer use. The study emphasizes the importance of renewable energy sources, such as solar energy, to reduce the environmental footprint of greenhouse systems and suggests improving resource efficiency in both cultivation methods to achieve sustainable agricultural practices
 
 
 
 
 
 
Conclusions
The study concludes that greenhouse cucumber cultivation, while more productive, has higher environmental impacts compared to open-field cultivation. This difference is primarily due to the increased consumption of energy, fertilizers, and other inputs in the greenhouse system. Specifically, greenhouse cultivation showed significantly higher consumption of electricity, nitrogen fertilizers, and manure, which contributed to greater environmental impacts such as global warming potential and ozone depletion. However, open-field cultivation, although requiring fewer inputs, results in lower environmental impacts but offers lower yields. The study emphasizes the need for optimizing energy consumption and reducing chemical inputs in greenhouse systems to mitigate their environmental footprint. The adoption of renewable energy sources, such as solar power, is recommended to make greenhouse farming more sustainable. Furthermore, a balanced approach combining both greenhouse and open-field cultivation, along with the use of clean energy technologies, is essential for achieving sustainable agricultural practices in the region.