نوع مقاله : مقاله پژوهشی

نویسندگان

• نجمه سالاری بردسیری ¹
• مجید حجازی مهریزی ²
• هرمزد نقوی ³
• ربیع بهروز ⁴
• مجید فکری ⁵

¹ دانشجوی دکتری

² دانشگاه شهید باهنر کرمان

³ هیئت علمی مرکز تحقیقات کشاورزی کرمان

⁴ دانشیار دانشکده منابع طبیعی و علوم دریایی، دانشگاه تربیت مدرس

⁵ استاد گروه علوم و مهندسی خاک، دانشکده کشاورزی، دانشگاه شهید باهنر کرمان، ایران

چکیده

نیاز به تأمین غذای مورد نیاز جمعیت جهان و کارایی پایین کودهای شیمیایی سبب استفاده بیش از حد کودهای شیمیایی شده است. یکی از روش‌های مؤثر جهت غلبه بر کارایی پایین کودهای شیمیایی، توسعه کودهای کندرها می‌باشد و پلی‌مرهای زیستی مانند سلولز مناسب‌ترین ترکیبات جهت ساخت کودهای کندرها می‌باشند. در این پژوهش، سلولز از سه نوع ضایعات شامل شاخه‌های درخت پسته، خرما و همچنین از کاغذ استخراج گردید. برای شناسایی سلولز استخراج شده با سلولز خالص، از روش طیف‌سنجی مادون قرمز استفاده شد. پس از استخراج سلولز، کودهای کندرهای اوره به نسبت 2 به 1(سلولز به اوره) به صورت قرص تولید و ویژگی‌های آن‌ها با استفاده از میکروسکوپ SEM و FTIR شناسایی شد. جهت ارزیابی کودهای کندرها در آزاد کردن نیتروژن، سینتیک آزاد‌سازی نیتروژن در 90 روز در قالب طرح کاملاً تصادفی در 3 تکرار در گلخانه مرکز تحقیقات کشاورزی کرمان بررسی شد. بازده استخراج سلولز برای کاغذ 70 درصد، خوشه خرما 33 درصد و شاخه پسته 28 درصد بدست آمد. همچنین نتایج میکروسکوپ الکترونی نشان داد که کود اوره به صورت ذرات سفید کروی اطراف ذرات میله‌ای سلولز قرار گرفته اند. روند سینتیک آزاد‌سازی نیتروژن برای تمام تیمارها کمتر از کود اوره خالص بود و بین تیمارها تفاوت معنی‌داری مشاهده و سلولز شاخه پسته باعث رهش کندتر کود اوره شده است. معادله سینتیک تابع توانی به عنوان بهترین مدل برای برازش داده‌های سینتیکی انتخاب شد. ضایعات مورد مطالعه در این پژوهش قابلیت بالایی جهت تولید سلولز خالص برای کندرها کردن کود اوره دارا می‌باشند.

کلیدواژه‌ها

• سلولز
• کود اوره
• کود کند‌رهش
• ضایعات

عنوان مقاله [English]

Production of Urea Slow-release fertilizer with cellulose from wastes (paper, palm and pistachios) and investigation of their structural, chemical and kinetic properties

نویسندگان [English]

• najmeh salari ardsiri ¹
• Majid Hejazi-Mehrizi ²
• hormazd naghavi ³
• rabi Behrooz ⁴
• Majid Fekri ⁵

¹ phd student

² Shahid Bahonar University of Kerman

³ Assistant Prof., Department of Soil and Water Research, Kerman Agricultural and Natural Resources Research and Education Center, AREEO,

⁴ 1. Associate Professor., Department of Wood and Paper Science and Technology, Faculty of Natural Resources and Marine Science, Tarbiat Modares University, Noor, Mazandaran, IranResources and Marine Science, Tarbiat Modares University, Noor, Mazandaran, Iran

⁵ Professor, Department of Soil Science, Faculty of Agriculture, Shahid Bahonar University of Kerman, Iran

چکیده [English]

Introduction providing the food needed by the world's ever growing population has led to changes in cultivated areas, water resources, and the overuse of chemical fertilizers and consequent environmental pollution. Providing essential nutrients to the plant is one of the most important factors related to the optimum production of agricultural crops. In recent years, most of essential nutrients are provided through the natural fertility of the soil and chemical fertilizers. Today, one of the most important ways to increase soil fertility is the use of fertilizers. Consistent and excessive use of fertilizers such as nitrogen and phosphorus (in the form of ammonium salts, urea, nitrate or phosphate compounds) in recent years has caused problems in the agriculture and environment. In recent years, the efficiency of application of nitrogen, phosphate and potash fertilizers has been about 30-35, 18-20 and 35-40-40, respectively. This indicates that a large part of the fertilizer used remains in the soil or enters the aquatic ecosystems and negatively affects the natural balance and biodiversity of agricultural lands. Accordingly, to overcome these problems, it is necessary to use solutions such as better water and fertilizer management, change in the structure of fertilizers and the use of new technologies. One of the effective methods to overcome the problems of low efficiency of chemical fertilizers is to develop the controlled release fertilizers. Slow-release fertilizers can be a good way to overcome the problems expressed by common chemical fertilizers. Release control fertilizers are usually prepared using the coating method and reducing the solubility of water-soluble fertilizers by creating a physical barrier. The biggest problem with slow release fertilizers is their high production cost. Therefore, it is necessary that the fertilizers covering chemical fertilizers be economical and compatible with the environment and have desirable coating properties. Nanocomposites are among the polymer coatings that have received much attention in recent research. Among the many materials used to form nanocomposites, polysaccharides such as cellulose, starch for economic reasons, biocompatibility, non-toxic and biodegradable are widely used compared to synthetic polymers. Despite many studies in the field of fertilizer production, the use of slow release fertilizers as a source of required nutrients and also the use of hydrophilic and hydrophobic polymers such as pure cellulose compounds with conventional fertilizers have not been studied. The need for this research is to use cellulose from agricultural waste in slow release of chemical fertilizers in order to increase the efficiency of fertilizers, prevent its overuse in agriculture, and also waste agricultural waste around orchards. In this study, cellulose compounds were extracted from paper, palm and pistachio branch and these cellulose compounds were then used to slow the release of urea fertilizers.

Materials and Methods First, the sufficient amounts of pruned wastes from branch of palm, pistachio, and paper waste, were collected from agricultural regions in Kerman Province; then they were transferred to the laboratory of Kerman Agricultural Research Center. After washing and drying, the samples were ground. In the next step, 10 g of each of the air-dried cellulosic sources was passed through a 60-mesh sieve in an Erlenmeyer flask with 200 ml of 1% NaOH solution for 1 h. Then, it was entirely washed with distilled water and the resulting contents in the Erlenmeyer flask were re-boiled along with a mixture containing 300 ml of 80% acetic acid plus 30 ml of 67% nitric acid for 30 min at 120°C. At the end of the reaction time and partial cooling of the mixture, the‌ cold distilled water was added to the reaction mixture and the resulting cellulose pastes were then washed thoroughly with distilled water until reaching the neutral pH. At the end, the samples were air-dried. Finally, the cellulose samples were washed with distilled water and air dried. In the second stage, slow release of urea fertilizer with cellulose from palm wastes in a ratio of 1 to 2 (fertilizer to cellulose) was made and they were made in the form of small tablets. Nitrogen release kinetics from these fertilizers in soil up to 90 days were measured and kinetic equations were also investigated.
Results and Discussion After cellulose extraction of wastes, FTIR device was used to identify the extracted celluloses and compare them with Sigma Aldrich pure cellulose. The peaks obtained from the FTIR apparatus were similar to the pure cellulose peaks. The yield of extracted cellulose in the form of paper waste was 70%> palm branch 33%> branch of pistachio 28%. In the second stage, the extracted cellulose was used to cover urea fertilizer in a ratio of 1 to 2 (urea fertilizer to cellulose) and the desired fertilizer was made in the form of small tablets with diameter of 0.5 cm and height of 2 cm. The SEM scanning electron microscope was used to study the structure of the manure. Microscopic images showed that the urea fertilizer placed as white spherical particles around the cellulose rod particles, indicating that the urea fertilizer particles adhered to the cellulose particles without any adhesive. The FTIR diagram of the fertilizer showed that the shift of the diagram upwards at the common wavelengths in urea and pure cellulose and a strong physical bond is established between them. Nitrogen release kinetics for all treatments that were less than pure urea fertilizer and significant differences observed between treatments and pistachio branch cellulose caused a slower release of urea fertilizer. The kinetic equation of the power function was selected as the best model for fitting the kinetic data. The studied wastes in this study have a high potential for producing pure cellulose to slow the release of urea fertilizer.

کلیدواژه‌ها [English]

• Cellulose
• Urea fertilizer
• Slow release fertilizer
• wastes