عنوان مقاله [English]
The controversy about sustainable agriculture has been extended to consider the impact of agricultural production. Population growth has increased the need for food, water, and renewable energy resources, which requires development of new knowledge about and technology for production systems using the sustainable development frameworks. As a consequence of agricultural reliance on natural resources and processes, a complicated relationship exists between agriculture and the environment. Agricultural activities can be both advantageous and disadvantageous for the environment. Agricultural activities have grown quickly over recent decades in Iran; their environmental impacts have also escalated. Major environmental issues in Iran include water shortages, nitrate leaching into ground water, soil erosion, and the release of pesticides and P-based fertilizers into water resources. Since there is a legal gap in assessing the environmental impact of agricultural activities in Iran; so little attention has been paid to reducing environmental emissions and use of resources of the agricultural products. Standard procedures should be used to assess agricultural activity to introduce environmentally-friendly practices and products. Crops production is a system with high environmental impacts. Different tools are available for assessment of the environmental impact of agricultural products. The most comprehensive of these is life cycle assessment (LCA). The present study used LCA to evaluate the materials used, energy consumption, and related environmental emissions from cradle to farm gate for soybean (Glycine max), sunflower (Helianthus annuus L.), and canola (Brassica napus) crops in Ardabil province of Iran.
Materials and methods
The basic guidelines for administering an LCA delineated in ISO standards 14040 and 14044 were observed in this research. LCA is an internationally standardized holistic assessment framework and is widely used to identify potential environmental emissions and resources throughout a product's lifecycle, particularly in the agro-food sector. Literature on LCA has demonstrated potential applications of LCA in agriculture. All environmental impacts were analyzed using Simapro v 8.0.1 software. The goal of the current analysis was to examine the environmental performance of conventional cropping practices of oilseed crops at the local level in Iran. The scope of the present research was limited to oilseed production system using all inputs and outputs of agricultural materials, energy, and water from cradle to farm gate in Ardabil. All materials, emissions, and water and energy consumption measured per 1 ton of a crop at 13% humidity are denoted as a FU. A system boundary covers the entire production system for soybean, sunflower, and canola. The inventory data was collected based on the commercial production of each crop. The goal of inventory questionnaire was to evaluate type of machinery, inputs and outputs and irrigation. Also, data collection involved face-to-face interview with farmers.
The impact categories investigated in this research were eutrophication, acidification, global warming potential, and photochemical oxidation. In addition, the impacts of water dependence and land use were examined.
Results and discussion
Only the classification and characterization stages of the LCA were considered in this research. The results showed that sunflower demonstrated a higher environmental load in five of the six categories because of its lower seed yield and higher water and energy demands. The results indicate that production of 1 ton of soybean and canola requires 370 and 471 m2 of land, respectively. Production of same quantity of sunflower required 426 m2 of land. Sunflower required 1.59 and 1.25 times more water than the canola and soybean respectively, to produce the same quantity of oilseed. It was found that the effects of these three crops comes generally from manufactured fertilizer, manure, diesel combustion, agricultural practices, and electricity for irrigation.
Generally, it can be said that the indirect effects associated with these inputs are related to producing and processing, which had higher impacts than those of the direct effects.