ارزیابی راهکارهای کاهش تقاضا برای آبیاری و سازگاری با کم آبی در استان فارس

سازگاری با کم‌آبی یکی از چالش‌های اصلی کشاورزی در ایران است. هدف از این مطالعه، ارزیابی ظرفیت صرفه‌جویی آب در بخش کشاورزی آبی استان فارس با استفاده از (1) بهینه‌سازی الگوی کشت، (2) کاربرد سایبان در باغ‌ها و مزارع تولید سبزی ‌و صیفی، (3) کاربرد مالچ‌کلش در باغ‌ها و مزارع، (4) تغییر نظام کشت غرقابی به هوازی برنج و (5) انتقال تولیدات سبزی‌ و صیفی از مزرعه به گلخانه است. برای این منظور از سامانۀ حسابداری آب (sawa) برای کشاورزی آبی استان فارس استفاده شد. حجم آب آبیاری کاربردی (خالص) در کشاورزی استان برای شرایط کشاورزان (نه شرایط پتانسیل و مطلوب) در الگوی کشت فعلی 4619 میلیون متر مکعب در سال برآورد و بهینه‌سازی الگوی کشت باعث کاهش 35 درصد از این حجم آب شده است. استفاده از مالچ‌کلش در الگوی کشت فعلی و بهینه به‌ترتیب 8 و 10 درصد، کاربرد سایبان به‌ترتیب 29 و 24 درصد و استفاده از نظام کشت هوازی برنج، به جای غرقابی، به‌ترتیب 4 و 1 درصد حجم آب کاربردی کشاورزان را کاهش می دهد. انتقال تولیدات سبزی ‌و صیفی از مزرعه به گلخانه در هر دو الگوی کشت فعلی و بهینه توانست حجم آب آبیاری کاربردی کشاورزان را 4 درصد کاهش دهد. نتایج بررسی ها نشان داد که ترکیب راهکارها در الگوی کشت فعلی و بهینه می‌تواند به ترتیب 66 و 48 درصد صرفه‌جویی در حجم آب آبیاری کاربردی کشاورزان استان ایجاد کند. پیشنهاد می‌شود که محققان، سیاست‌گذاران و بهره‌برداران بخش کشاورزی با ارزیابی و مطالعات تکمیلی به سمت رفع موانع و گسترش استفاده از این راهکارهای ارزشمند و دوست‌دار محیط‌زیست حرکت کنند.

assessment of options to reduce irrigation demand and adaptation to water scarcity in fars province

introduction over-withdrawal of water in the agricultural sector of iran is one of the most important factors that threatens the sustainability of agricultural production and natural resources. therefore, appropriate approaches should be used to eliminate this factor. in this study, the water saving capacity in the irrigated agricultural sector of fars province was examined using some options that decrease irrigation demand in fields and orchards. these options are: (1) optimization of cropping pattern with the aim of minimizing water use, (2) using shade net in gardens and vegetable farms, (3) using straw mulch in gardens and farms though implementation of conservation tillage, (4) changing the current flooded rice cultivation system to aerobic system, and (5) transferring vegetable production from the farm to the greenhouse. the effects of the options were assessed individually and in combination. methodologythe system for regional agricultural water balance and accounting (sawa) set up for irrigated agriculture lands in fars province was used. the core of this system consists of a plant simulation model (ssm-icrop2). for each of the water saving option of this study, a separate sawa system was prepared and the amount of irrigation water used in agriculture in the province was estimated and compared. the system provides crop yield and irrigation water under farmer’s and potential conditions as influenced by climate, soil, management and crop. the system estimates were based on 10-year meteorological data (2011-2021), 5-year average crop area statistics (2017-2021), and yield, price, and cost of production data for plants in 2021. results and discussionthe results showed that the applied irrigation water in agriculture in the province for farmers’ conditions (not for potential or optimal conditions) under the current cropping pattern is 4619 million cubic meters per year (net irrigation water without considering irrigation efficiency and uneven water distribution). optimization of the cropping pattern reduced this figure by 35% (a reduction equivalent to 1616 million cubic meters per year). optimizing the cropping pattern was done with the aim of minimizing the amount of irrigation water applied under farmers’ conditions in the entire province provided that the farmers profits in the optimized pattern would not change and the area under cultivation of perennial plants and legumes, which play an important role in agricultural sustainability, would not decrease.the implementation of 2 t/ha straw mulch vias conservation tillage for all crops except for rice and alfalafa in the current and optimal cropping patterns reduced the net applied water by 8 and 10%, respectively (equivalent to 384 and 292 million cubic meters per year), the use of shade net (decreases solar radiation by 50%) during the summer months in the current and optimal cropping patterns reduced the applied water by 29 and 24%, respectively (equivalent to 1331 and 713 million cubic meters per year), and the use of aerobic rice cultivation system instead of flooding system in the current and optimal cropping patterns reduced the applied water by 4 and 1%, respectively (equivalent to 185 and 37 million cubic meters per year). transferring vegetable production from the field to the greenhouse in both the current and optimal cultivation patterns was able to reduce the applied irrigation water by 4 percent (equivalent to 167 and 137 million cubic meters per year, respectively). however, combination of water saving options in the current and optimal cropping patterns could save irrigation water by 66 and 48% (equivalent to 3048 and 1444 million cubic meters per year), respectively. conclusionsthe findings of this study indicate that the evaluated options provide safe and effective solutions for addressing water scarcity in the irrigated agriculture of fars province. therefore, it is recommended that executive officials, policymakers, and agricultural sector stakeholders work toward eliminating barriers and promoting the widespread adoption of these valuable options through evaluation and additional studies. by doing so, sustainable agricultural practices can be achieved, contributing to a healthier environment and preventing further ecological degradation.