ارزیابی پایداری مبتنی بر امرژی در پنج بوم‌نظام عمده کشاورزی هیرمند، استان سیستان و بلوچستان

کشاورزی نقش اساسی در حمایت از معیشت خانواده و توسعه اقتصاد ملی دارد. شیوه‌های کشاورزی تا حد زیادی میزان تولید غذا و وضعیت محیط را تعیین می نمایند. رهیافت تحلیل امرژی با کمی سازی جریان‌های ورودی محیطی و اقتصادی به واحد یکسان امژول‌خورشیدی توانایی مقایسه جامع نظام‌های تولیدی مختلف را داراست. در مطالعه حاضر، پایداری بوم شناختی پنج نظام تولید محصولات زراعی گندم، جو، یونجه، هندوانه و خربزه در سطح شهرستان هیرمند، واقع در استان سیستان و بلوچستان، با استفاده از ارزیابی ساختار امرژی و تحلیل شاخص‌های امرژی بررسی شد. داده‌های موردنیاز برای این پژوهش توسط پرسش‌نامه و اندازه گیری های میدانی از سطح نظام‌های کشاورزی خرده مالکی شهرستان هیرمند در سال 1399 جمع آوری گردید. جریان‌های رایگان تجدیدپذیر و تجدیدناپذیر به ترتیب 46/77، 45/87، 64/39، 63/94 و 62/40 درصد از کل امرژی ورودی نظام‌های تولید گندم، جو، یونجه، هندوانه و خربزه را به خود اختصاص دادند. سهم زیاد نهاده‌های رایگان داخلی نشان می‌دهد که غالب مزارع مورد مطالعه، نظام‌هایی غیر صنعتی هستند که به شیوه نیمه‌سنتی و کم نهاده مدیریت می‌شوند. مقادیر محاسبه‌شده برای شاخص پایداری امرژی (esi) نشان داد، پایداری بوم‌شناختی نظام تولید یونجه بیشتر از سایر نظام‌های مورد مطالعه است. دلیل اصلی پایداری بیشتر این نظام سهم زیاد انرژی ورودی مربوط به نهاده‌های محیطی رایگان و منابع تجدید پذیر اقتصادی بود. همچنین بالا بودن نسبت عملکرد امرژی، مقدار انرژی صرف شده کمتر در تولید هر واحد خروجی و بهره‌وری بیشتر کل عوامل تولید حاکی از مزیت نسبی بیشتر نظام تولید یونجه است. درمجموع ارزیابی‌های انجام‌شده بر اساس محاسبه شاخص‌های مبتنی بر امرژی نشان داد در نظام‌های زراعی غالب شهرستان هیرمند، توجه به راهکارهای عملی در مدیریت جامع بوم‌نظام تولیدی به‌ویژه حفاظت از مواد آلی خاک و جلوگیری از فرسایش خاک و تلفات مواد آلی خاک، می‌تواند در پایداری بوم‌شناختی این نظام‌ها تاثیر چشمگیری داشته باشد.

assessing emergy-based sustainability in five major agricultural ecosystems in hirmand, sistan and baluchestan province

introduction: agriculture is crucial for sustaining family livelihoods and advancing the national economy. food production and environmental conditions are heavily influenced by agricultural practices. by converting environmental and economic input currents to the same unit of solar emjoule (sej), the emergy analysis method can comprehensively compare various production systems. using the evaluation of the emergy structure and the analysis of emergy-based indicecs, the ecological sustainability of five crop production systems of wheat, barley, alfalfa, watermelon, and melon in hirmand city, sistan and baluchestan province, was investigated in the present study.materials and methods: face-to-face questionnaires were administered to producers of wheat, barley, alfalfa, watermelon, and melon products in hirmand city from 18 villages where significant agricultural products were produced in 2020. all information regarding crop inputs and outputs was gathered using two methods: verbal estimates using a questionnaire; field measurements and authors’ observations; and field estimates using a questionnaire. during the same time frame, the information provided by the farm manager and staff was thoroughly evaluated. in this study, zabol and zahak meteorological stations provided long-term meteorological data.first, the spatial and temporal boundaries of five systems for emergy analysis were determined, and then the emergy diagram for the studied systems was drawn based on the classification of inputs, renewable or nonrenewable resources, local or imported. sunlight, wind, chemical energy and geological potential energy of precipitation, river water, and evapotranspiration of renewable water are examples of renewable environmental resources (r). nonrenewable environmental resources (n), such as soil erosion, soil organic matter losses, groundwater, and evaporation of groundwater; purchased renewable resources (fr), including 80 percent organic fertilizer, between 15 and 25 percent seed, 10 percent labor, and 7 percent electricity. purchased nonrenewable resources (fn) consist of agricultural machinery, fossil fuels, fertilizers, and chemical pesticides, 93 percent of electricity, 90 percent of labor, 75 percent to 85 percent of seeds, and 20 percent of organic fertilizer. next, all input (u) and output (y) currents, raw data for all production systems were estimated and multiplied in joules, grams, or rials based on iranian conditions for their unit emergy value.results and discussion: free renewable and nonrenewable flows made up 46.77, 45.87, 64.39, 63.94, and 62.40 percent, respectively, of the total emergy input flows of wheat, barley, alfalfa, watermelon, and melon production systems. the high proportion of free domestic inputs suggests that the majority of the studied farms are semi-traditional, low-input, non-industrial systems. according to the calculated values of the emergy sustainability index (esi), the ecological sustainability of the alfalfa production system is greater than that of other studied systems. the greater sustainability of this system was primarily due to the high proportion of emergy input from environmental inputs and economic renewable resources.in addition, the emergy yield ratio (eyr), the amount of energy used to produce each unit of output, and the productivity of all production factors indicate that the alfalfa production system has a greater comparative advantage. according to the emergy investment ratio (eir) values in the present study, the barley production system had the highest rate of this index, while the alfalfa production system had the lowest rate. in barley and wheat production systems, the highest proportion of total emergy was contributed by chemical fertilizers and labor. due to the greater use of free renewable environmental inputs, the alfalfa production system had the lowest eir index value. according to the emergy index of agricultural product safety (eips), the alfalfa production system had the highest level of crop production health, while the watermelon production system had the lowest level. since the input of chemical fertilizers and herbicides is the most important factor in the eips index, the low index of the watermelon production system can be attributed to the high proportion of chemical fertilizers and herbicides in this system.conclusion: in general, the evaluations based on the calculation of emergy-based indices revealed that in the dominant agricultural systems of hirmand city, focusing on practical solutions in comprehensive management of production system, particularly protection of soil organic matter and prevention of erosion and loss of soil organic matter, can sustain these ecosystems and have a dramatic effect. due to the lack of organic matter in the soils of the study area, the cultivation of perennial, rhizobium- and nitrogen-fixing plants with deep roots, such as alfalfa, improves soil fertility. this stabilizes the production system by enhancing the economic performance of farmers, soil fertility, and structure.