ارزيابي اثرات زيست محيطي توليد ذرت علوفه اي (Zea mays L) در خراسان جنوبي

Evaluate the Environmental Impact of Silage Corn Production in South Khorasan Province

اين مطالعه با هدف ارزيابي اثرات زيست محيطي توليد ذرت علوفه اي (Zea mays L) در استان خراسان جنوبي انجام شده است. براي اين منظور از رويكرد ارزيابي چرخه حيات (LCA) استفاده و براي ارائه نتايج كاربردي تر و همچنين تخمين ظرفيت كاهش اثرات زيست محيطي با تكنيك تحليل فراگير داده ها تركيب شد. اطلاعات مورد نياز با استفاده از پرسشنامه و مصاحبه رو در رو با كشاورزان و كارشناسان كشاورزي گردآوري و با استفاده از بسته نرم افزاري DEAP2.1 ، Simapro7 تجزيه و تحليل شد. اثرات زيست محيطي براي توليد يك تن ذرت علوفه اي و با استفاده از روش IMPACT 2002+ كه 15 شاخص اثر مياني و چهار شاخص اثر پاياني را شامل مي شود، ارزيابي شد. نتايج كارايي نشان داد ميانگين كارايي فني و كارايي خالص فني و كارايي مقياس به ترتيب 0/80، 0/93 و 0/86 است. نتايج ارزيابي چرخه حيات نشان داد بيشترين بار محيطي در كشت ذرت علوفه اي مربوط به شاخص مواد آلي غير تنفسي و پس از آن شاخص هاي اثر گرمايش جهاني، انرژي تجديدناپذير و مواد سرطان زا در رده هاي بعد قرار دارند. ارزيابي طبقات آسيب نشان داد كه بيشترين تاثير بر روي شاخص سلامتي انسان بوده و شاخص تغييرات اقليم و منابع در رده هاي بعدي قرار دارند. نتايج شاخص هاي اثر در صورتي كه واحد هاي ناكارا با اصلاح الگوي مصرف خود را به مرز كارايي برسانند، بين 3/28 درصد (اثر مواد سرطان زا) تا 28/25 (مسموميت خاكي) درصد كاهش خواهند يافت. شاخص هاي اثر استخراج مواد معدني با 25/01 درصد كاهش و اشغال زمين و امواج يونيزه كننده با 20/81 درصد پس از شاخص اثر مواد سرطان زا بيشترين ميزان كاهش را نشان دادند. همچنين در بين نهاده هاي توليد الكتريسيته، كود حيواني و انتشارات درون سيستمي مهمترين نقش را در تاثيرات زيست محيطي توليد ذرت علوفه اي در منطقه داشتند. اصلاح نظام آبياري و سيستم پمپاژ آب به منظور كاهش مصرف آب و الكتريسيته و همچنين ترغيب و آگاهي بخشي به كشاوزان در جهت استفاده بهينه از كودهاي شيميايي و استفاده از كود سبز به جاي ساير كودها به منظور كاهش اثرات زيست محيطي توليد ذرت علوفه اي در منطقه توصيه مي شود.

Introduction The discussions on environmental sustainability have eventually come to include agricultural products in recent years. LCA is an ISO-standardized method, in which an inventory is used to determine the inputs and emissions associated with each stage of production life cycle and to express their quantitative share in a specific impact category. Southern Khorasan Province is the most eastern province in Iran. Drought and increased price of forage in this province have turned the growing of silage corn into an economical attraction for this province. Consequently, it is necessary to environmentally evaluate this crop in order to have more comprehensive understanding of its production, in addition to its economical evaluation. In this study was tried to examine the environmental impacts of silage corn production by an integrated LCA and DEA method to better understand its production and to recommend approaches for mitigating its environmental impacts. Materials and Methods Data were collected by questionnaire and face-to-face interviews with farmers and agriculture experts and analyzed using DEAP2.1 and Simapro software. An LCA project has four phases include goal and scope definition, life cycle inventory analysis, life cycle impact assessment, and Interpretation. An important part of goal and scope definition is to select system boundaries. The focus of the present study is on production phase and on-farm processes. In fact, farm gate is selected as system boundary and all of environmental impact estimated for the production of one tone of product. Various methods have been introduced by different institutions and countries for environmental impacts assessment. One of them is IMPACT 2002+ method which is a combination of three methods of IMPACT 2002, Eco-Indicater 99andCML. This method is selected because it assesses 15 impact indicators, and it assesses four end point indicators (damage category) by combining these impact indicators. The consumption of inputs within the studied system boundary will result in direct emission of pollutants into air, water and soil. These emissions have been calculated according to the literature. Results and Discussion Results for efficiency showed that mean technical efficiency, pure technical efficiency and scale efficiency were 0.80, 0.93, and 0.86, respectively. In CCR mode, 13 units and in BCC mode, 22 units were efficient. Technical efficiency varied in 0.33-1 range with 0.20 SE. The lowest pure technical efficiency was 0.64 with 0.10 SE. If inefficient units could approach efficiency boundary by adjusting their consumption pattern, the results for impact categories could be reduced by 3.2-28.2%. The lowest reduction (3.3%) was the indicator of carcinogens, and the highest reduction ( 28.2%) was terrestrial ecotoxicity followed by mineral extraction with 25.01% reduction and land occupation and ionizing radiation with 20.8% reduction. Normalized results showed that the highest environmental burden in silage corn production was related to Respiratory inorganics followed by global warming, non-renewable energy and carcinogens. Environmental burden of electricity had the highest impact on environment pollution in five impact indicators (carcinogens, non-carcinogens, aquatic toxicity, global warming, and non-renewable energies). The assessment of damage categories revealed that the highest effect was on human health and then, on climate change and resources. Electricity, manure and on system emissions also played the most important role in environmental impacts of silage corn production in this region. Conclusion According to the results of the present study on the one hand and the necessity for silage corn production in the region to meet livestock sector’s demand on the other hand, reform in irrigation system and water pumping system to reduce water and electricity use as well as motivating farmers to analyze soil to determine the optimum fertilization rate and increasing their understanding of how to apply this input are the most important factors to reduce environmental impacts of silage corn production in the region.