عنوان مقاله [English]
Food security and sustainable agriculture are among the most challenging issues for human beings in the present age. These daunting challenges have arisen in the face of dramatic population growth as well as rising living standards, life style and, as a result, increased demand for a variety of foods. Due to limited water resources and arable lands, to achieve more production, it is necessary to increase the yield per unit area by using more materials (e.g., chemical fertilizers, pesticides, and fossil fuels) and energy. Obviously, in addition to the higher cost, it will lead to irreparable environmental consequences. In this regard, to achieve more sustainable production of agricultural products, there is a need to carefully evaluate the environmental status of these products in order to identify environmental hotspots to optimize them. Due to this fact, a study was conducted to assess the environmental damages of soybean production system in different cities of Mazandaran province with a life cycle assessment (LCA) perspective.
Materials and Methods
In the present survey, LCA approach was applied to evaluate the environmental impact and determine the most important hotspots of soybean produced in the cities scale of Mazandaran province (13 cities with soybean cultivation). LCA is a method which examines the environmental impacts associated with a product (or process) throughout its lifetime by accounting resources consumption and pollutant emissions. For this purpose, the farm gate was considered as the system boundary. Necessary data for LCA inventory were also obtained through face to face interview with 303 farmers in 2019 and the EcoInvent 3.5 database in SimaPro 126.96.36.199 software. The potential environmental impacts were assessed by IMPACT2002+ (v2.15) model in the software based on 1 ton of soybean seed produced as the functional unit (FU). Finally, impact assessment results of the soybean production system were presented in four environmental damage groups: human health, ecosystem quality, climate change and resources.
Results and Discussion
The findings revealed that soybean cultivation in the region and under the current conditions of inputs consumption has the highest impact on human health indicator that direct emissions from diesel fuel combustion and application of chemical fertilizers in the field play a major role in this damage category. Direct emissions from field operations claimed the highest share (>51%) in increasing global warming potential, which was mainly a result of CO2 emissions from burning diesel fuel. In addition, the findings of the present study showed that diesel fuel followed by nitrogen fertilizer had the most substantial role in the resources damage category. More generally, the total environmental damage for the production of 1 ton of soybean seed in surveyed cities ranged from 228.76 to 439.77 mPt, among which the cities of Galugah and Qaemshahr (228.76 and 261.18 mPt, respectively) had the least and Amol and Sari (438.06 and 439.77 mPt, respectively) had the most value. To sum up, the LCA approach has been able to quantify the contribution of soybean production system in causing environmental damage in the form of different damage categories by considering the amount of each of the inputs and their emissions based on a specific FU.
In total, it can be concluded that diesel and chemical fertilizers inputs, and direct emissions caused by their consumption in farms were the most substantial environmental hotspots. These factors, in turn, arise from the mismanagement of soybean farms in Mazandaran. Hence, it seems that efficient management practices by informing farmers and support of the authorities to provide appropriate facilities to farmers can be an important step towards reducing the environmental consequences and developing the cultivation of this valuable crop in the region.
The authors would like to acknowledge the financial support of Tarbiat Modares University as well as the assistance of the esteemed officials of Sari Agricultural Sciences and Natural Resources University, Agriculture-Jihad Organization of Mazandaran province and especially the honorable farmers of this province to collect data for this study.
Keywords: Ecosystem quality, Global warming, Human health indicator, Life cycle impact assessment