Bramanta, Herdy (2026) Formulasi dan Karakterisasi Controlled Release Fertilizer NPK dengan Pelapis Biodegradable Polimer Pati–Gliserol Menggunakan Asam Sitrat dan Sodium Tripolyphosphate (STPP) sebagai Crosslinker. Masters thesis, Institut Teknologi Sepuluh Nopember.
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Abstract
Pupuk lepas terkendali (Controlled Release Fertilizer, CRF) dikembangkan untuk meningkatkan efisiensi penggunaan hara dan mengurangi kehilangan nutrisi akibat pencucian, limpasan, serta volatilisasi. Penelitian ini bertujuan mengembangkan pupuk NPK 15–15–15 lepas terkendali menggunakan pelapis biodegradable berbasis pati jagung–gliserol dengan crosslinker asam sitrat (SCAG) dan natrium tripolifosfat (SPG), serta mengevaluasi karakteristik pelapis, perilaku pelepasan unsur hara, kinetika pelepasan, dan pengaruhnya terhadap pertumbuhan tanaman jagung. Formulasi pelapis dioptimasi berdasarkan daya serap air, kekuatan tarik, swelling, dan analisis FTIR, kemudian diaplikasikan pada granula pupuk menggunakan pan granulator dan dikarakterisasi menggunakan SEM–EDS. Kinerja pupuk dievaluasi melalui uji pelepasan N, P, dan K pada media air dan tanah, analisis model kinetika, serta uji pertumbuhan jagung di rumah kaca. Hasil penelitian menunjukkan bahwa formulasi optimum diperoleh pada SCAG-2 dan SPG-2. Analisis FTIR mengonfirmasi terbentuknya ikatan silang pada kedua sistem, sedangkan hasil SEM menunjukkan bahwa pelapis SCAG memiliki ketebalan 46,71–51,10 μm dan pelapis SPG memiliki ketebalan 27,57–28,33 μm. Pada media air, pelapis SPG memperpanjang waktu pelepasan sempurna hingga 28 jam untuk nitrogen, 32 jam untuk fosfor, dan 20 jam untuk kalium. Pada media tanah, pupuk berlapis SPG hanya melepaskan 20,1% nitrogen, 26,3% fosfor, dan 40,2% kalium setelah 25 hari, lebih rendah dibandingkan SCAG. Pelepasan nitrogen dan fosfor mengikuti model Korsmeyer–Peppas, sedangkan pelepasan kalium mengikuti model orde satu. Uji rumah kaca menunjukkan bahwa pupuk berlapis SPG menghasilkan pertumbuhan jagung terbaik dengan tinggi tanaman 82,25 cm, diameter batang 28,75 mm, panjang daun 98,25 cm, dan jumlah daun 11,25 helai pada umur 45 hari. Secara keseluruhan, hasil penelitian menunjukkan bahwa pelapis biodegradable berbasis pati jagung dengan crosslinker natrium tripolifosfat mampu mengendalikan pelepasan hara secara lebih efektif, meningkatkan efisiensi penggunaan hara, dan berpotensi dikembangkan sebagai pelapis pupuk lepas terkendali yang ramah lingkungan untuk mendukung pertanian berkelanjutan.
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Controlled-release fertilizers (CRFs) have been developed to improve nutrient use efficiency while minimizing nutrient losses through leaching, runoff, and volatilization. This study aimed to develop a controlled-release NPK 15–15–15 fertilizer using biodegradable corn starch–glycerol coatings crosslinked with citric acid (SCAG) and sodium tripolyphosphate (SPG), and to evaluate the coating characteristics, nutrient release behavior, release kinetics, and their effects on maize growth. The coating formulations were optimized based on water absorbency, tensile strength, swelling behavior, and Fourier Transform Infrared (FTIR) analysis, followed by application onto fertilizer granules using a pan granulator. The coated fertilizers were characterized using Scanning Electron Microscopy coupled with Energy-Dispersive X-ray Spectroscopy (SEM–EDS). Fertilizer performance was evaluated through nitrogen (N), phosphorus (P), and potassium (K) release tests in water and soil media, release kinetic modeling, and a greenhouse maize growth experiment. The results showed that SCAG-2 and SPG-2 were the optimum coating formulations. FTIR analysis confirmed the formation of crosslinked polymer networks in both coating systems, while SEM analysis revealed coating thicknesses of 46.71–51.10 μm for SCAG and 27.57–28.33 μm for SPG. In the water release test, the SPG coating prolonged complete nutrient release to 28 h for nitrogen, 32 h for phosphorus, and 20 h for potassium. In the soil release test, SPG-coated fertilizer released only 20.1% of nitrogen, 26.3% of phosphorus, and 40.2% of potassium after 25 days, indicating a slower release than the SCAG-coated fertilizer. Nitrogen and phosphorus release followed the Korsmeyer–Peppas model, whereas potassium release was best described by the first-order kinetic model. The greenhouse experiment demonstrated that SPG-coated fertilizer produced the best maize growth, achieving a plant height of 82.25 cm, a stem diameter of 28.75 mm, a leaf length of 98.25 cm, and 11.25 leaves per plant after 45 days. Overall, these findings demonstrate that biodegradable corn starch-based coatings crosslinked with sodium tripolyphosphate effectively regulate nutrient release, improve nutrient use efficiency, and exhibit strong potential as environmentally friendly coating materials for controlled-release fertilizers to support sustainable agricultural practices.
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