PENGGUNAAN KITOSAN-POLIVINIL ALKOHOL (PVA)-KALSIUM KARBONAT SEBAGAI MATRIKS UREA SLOW-RELEASE FERTILIZER (SRF)

USING OF CHITOSAN-POLYVINYL ALCOHOL (PVA)-CALCIUM CARBONATE AS MATRIX FOR UREA SLOW-RELEASE FERTILIZER (SRF)

Pupuk urea bersifat higroskopis dan mudah hilang di lingkungan sehingga efisiensi penyerapan nutrisi tanaman menurun. Untuk meningkatkan efisiensi penyerapan nutrisi, urea perlu dimodifikasi menjadi slow-release fertilizer (SRF) dengan pelapis berbasis kitosan, polivinil alkohol (PVA), dan kalsium karbonat (CaCO₃). Kitosan adalah polimer ramah lingkungan yang mudah dimodifikasi, PVA memiliki fleksibilitas tinggi, dan kalsium karbonat bersifat hidrofobik. Penelitian ini bertujuan melakukan pembuatan dan karakterisasi SRF urea termodifikasi matriks kitosan-PVA-CaCO₃ untuk meningkatkan efektivitas pelepasan urea. SRF urea dicetak dalam bentuk membran menggunakan 3 variasi kalsium karbonat, yaitu 0,01% (b/v) (C1), 0,05% (b/v) (C2), dan 0,1% (b/v) (C3). Karakterisasi meliputi massa, ketebalan, swelling, porositas, morfologi permukaan, penampang melintang dan komposisi unsur menggunakan Scanning Electron Microscope (SEM) dan Energy Dispersive X-Ray (EDX), serta identifikasi gugus fungsi SRF menggunakan Fourier Transform Infra-Red (FTIR). Uji pelepasan urea selama 40 hari menggunakan Spektrofotometri UV-VIS dan menentukan kinetika pelepasan urea. Pengaplikasian SRF urea pada tanaman sawi hijau selama 14 HST. Formula terbaik diperoleh pada konsentrasi 0,01% (C1) dengan massa 0,01866 gram, ketebalan 0,036 mm, swelling 202,5%, porositas 15,56%, dan morfologi permukaan berpori dengan ukuran asimetris serta penampang melintang berongga, EDX menunjukkan adanya elemen C, N, O dan Ca. Gugus fungsi OH, NH, Ca-O, C-H, C=O, C-N, dan C-O terdeteksi melalui FTIR. SRF urea C1 memiliki pelepasan urea yang paling optimal sebesar 80,20% sesuai dengan model Korsmeyer peppas, dibuktikan dengan produktivitas tanaman sawi yang paling tinggi mencapai 20,5 cm dan tampak subur yang dibuktikan dengan jumlah 6 daun.

Kata Kunci: Kalsium karbonat, Slow-Release Fertilizer, Urea

Urea fertilizer is hygroscopic and easily lost to the environment, which reduces the efficiency of nutrient absorption by plants. To improve nutrient uptake efficiency, urea needs to be modified into a Slow-Release Fertilizer (SRF) coated with chitosan, polyvinyl alcohol (PVA), and calcium carbonate (CaCO₃). Chitosan is an environmentally friendly polymer that is easily modified, PVA offers high flexibility, and calcium carbonate is hydrophobic, helping to slow excessive urea release. This study aims to fabricate and characterize a urea SRF with a chitosan–PVA–CaCO₃ matrix to enhance controlled nutrient release. The urea SRF was cast in membrane form using three concentrations of calcium carbonate: 0,01% (b/v) (C1), 0,05% (b/v) (C2), and 0,1% (b/v) (C3). Characterization included measurements of weight, thickness, swelling ratio, porosity, surface and cross-sectional morphology using a Scanning Electron Microscope (SEM), elemental composition analysis using Energy Dispersive X-Ray (EDX), and functional group identification using Fourier Transform Infrared Spectroscopy (FTIR). The urea release test was conducted over 40 days using UV–Vis Spectrophotometry, and the release kinetics were determined. The SRF urea was also tested on green mustard plants (Brassica juncea L.) for 14 days after planting. The best formulation was obtained at a calcium carbonate concentration of 0,01% (C1) with a mass of 0,01866 grams, thickness of 0,036 mm, swelling of 202,5%, porosity of 15,56%, a porous surface morphology with asymmetric pore sizes, and a hollow cross-section. EDX analysis confirmed the presence of C, N, O, and Ca elements. Functional groups including OH, NH, Ca–O, C–H, C=O, C–N, and C–O were detected through FTIR analysis. The C1 urea SRF exhibited the most optimal urea release of 80,20% following the Korsmeyer peppas model, as demonstrated by the highest productivity of mustard greens, reaching a height of 20,5 cm and appearing healthy with six leaves.

Keywords: Calcium carbonate, Slow-Release Fertilizer, Urea