طراحي و پياده‌سازي دستگاه كشت هيدروپونيك دوار خورشيدي مجهز به سامانه هوشمند آبياري

Design and Development of a Solar Hydroponic Rotary Cropping Apparatus with an Intelligent Irrigation System

افزایش نیاز به غذا لزوم اصلاح الگوی كشت با هدف بیشترین تولید محصول، با كمترین مصرف نهاده‌ها و در هر شرایط اقلیمی را ضروری ساخته‌ است. در این راستا، دستگاه كشت هیدروپونیك دوار خورشیدی مجهز به سامانه هوشمند آبیاری طراحی و ساخته شد. در این دستگاه كه گیاهان در سینی‌هایی در محیط یك استوانه دوار، رو به محور مركزی (محل نور مصنوعی) رشد می‌كنند تراكم كشت تا حد زیادی افزایش می‌یابد، بخشی از انرژی مورد نیاز ازطریق پنل‌های فتوولتائیك تأمین شده و آبیاری گیاهان (تماس سینی‌ها با آب مخزن زیرین) با تشخیص نیاز آبی براساس برآوردهای فازی تبخیر و تعرق با ورودی‌های دما، رطوبت هوا و نور صورت می‌گیرد. ارزیابی عملكرد سامانه با كشت كاهو در دو وضعیت آبیاری مبتنی بر تشخیص نیاز آبی (روش فازی) و بدون آن (روش On/Off) صورت گرفت. برطبق نتایج، در كشت فازی، گیاهان به‌طور متوسط روزانه lit 2/18 آب را به‌صورت تبخیر و تعرق از دست دادند. سامانه خورشیدی به‌طور متوسط 51/16% از نیاز سالانه را تأمین نمود و در دو كشت فازی و On/Off به‌ترتیب 58/81% و 48/41‌% انرژی مورد نیاز (در زمستان) از تابش خورشیدی حاصل گردید. تمامی شاخص‌های رشدی گیاه در كشت فازی به‌شكل معنی‌داری از On/Off بهتر بود و برای تولید هر كیلوگرم محصول كاهو در كشت فازی نسبت به On/Off نیاز به 43% مساحت كمتر، 56% آب كمتر و 74% انرژی كمتر بود. در این سامانه در مقایسه با روش مزرعه‌ای، تراكم كشت و میزان آب مورد نیاز برای پرورش هر بوته كاهو به‌طور متوسط به‌ترتیب 12 برابر بیشتر و 15 برابر كمتر بود.

Introduction Global increase in the food demand and challenges regarding the water, energy and fertile soil has made it clear that current strategies are no longer efficient for maintaining food safety. Therefore, attention to novel, science-based, seasonal and climate-independent farming methods which could result in the higher crop quality and quantity is an inescapable decision. Among all agricultural practices and technologies, intensive culture and hydroponic methods in controlled environments play an important role. Materials and Methods To address these challenges, an indoor solar-powered auto-irrigate rotary cropping system (SARCS) was designed and implemented. Arrangement of plants in the surface area of an open-ended drum makes it possible to use space rather than area to maximize the acreage. An embedded fuzzy control system managed the irrigation process based on the plant water requirement predictions, and photovoltaic panels (PVs) was responsible for system electrical energy provision. The drum rotates around its horizontal axis where LED lamps are positioned to provide light to plants. This structure causes the plants gain the light illumination efficiently while getting access to water accumulated in the secondary tank positioned beneath the drum. Fertigation fuzzy control was based on plant evapotranspiration (ET) estimations with temperature, humidity, and light as its inputs. The instantaneous estimated ETs which were measures for root substrate moisture were summed until reaching its critical value which is equivalent to plant readily available water (RAW). This tends to trigger a pump submerged in a primary tank to fill the secondary one up to a predefined height ruled by a level sensor. The solar energy system consisted of PVs, MPPT, inverter, and battery bank. The SARCS evaluation procedure included two valid lettuce cultivation in grow bags filled with the same proportions of perlite and coco peat as a root substrate. The first cultivation used water level sensors to rule the irrigation process (non-fuzzy) while the second one (fuzzy) were governed by fertigation cycle fuzzy control. Results and Discussion The results showed that employing these two modes increased lettuce planting density to about 12 times in the field culture and 4 times in the greenhouse. The energy consumption evaluation revealed that in fuzzy and non-fuzzy approaches the same amounts of energy were needed. But in fuzzy mode the amount of energy consumed per kilogram of marketable lettuce was 74.33% less than in non-fuzzy mode. Fuzzy and non-fuzzy modes utilized 58.81% and 48.41% of the total energy requirements from PVs, respectively. It was calculated that the solar system is able to supply 51.16 % of SARCS total annual energy requirements in Karaj Province. The results of water consumption evaluations revealed that the fuzzy approach could cut the needed water to 24%, and improved the marketable product to 74.47%. For producing one kilogram dry and fresh biomass, fuzzy mode used 50.41% and 55.53% less water than non-fuzzy, respectively. Furthermore, one kilogram marketable product in fuzzy approach needed 56.46% less water than in non-fuzzy. The averaged water needed for growing one lettuce plant in non-fuzzy and fuzzy modes were 15 times less than in field lettuce. The comparison of growth parameters of harvested lettuce in the two studied approaches revealed that fuzzy mode would have significantly higher results in all parameters. Conclusions The results suggested that the development of intensive culture strategies would play an important role in the sustainable agricultural production and food safety. Also, the solar energy utilization in farming practices could save fossil resources and decrease air pollutions. Finally, purposeful irrigation approaches which are based on plant water requirement predictions can significantly reduce the total water consumption and improve products quality. This strategy, therefore can be introduced to other farming practices such as field and greenhouse methods.