Electronic Theses and Dissertation

Putri Cut Habibi. (2026). Pembuatan Komposit Urea Slow Release yang dapat Berperan Ganda sebagai Pupuk dan Media Tanam Penyimpanan Air. [Skripsi. Universitas Syiah Kuala]. Di bawah bimbingan Prof. Dr. Adlim, M.Sc., dan Drs. Rusman, M.Si.

Pupuk urea merupakan sumber nitrogen yang banyak digunakan dalam budidaya tanaman, namun efisiensi pemanfaatannya relatif rendah karena nitrogen hasil hidrolisis urea mudah hilang melalui proses denitrifikasi, pencucian (leaching) dan volatilisasi amonia sebelum terserap secara optimal oleh tanaman. Salah satu upaya untuk meningkatkan efisiensi penggunaan urea adalah dengan mengembangkan slow release fertilizer (SRF). Penelitian ini bertujuan untuk menentukan komposisi optimal pupuk urea SRF berbahan sponge loofah, serbuk gergaji, dan abu sekam padi, mengetahui karakteristik fisik komposit, serta amonia sebagai indikator pelepasan nitrogen. Pembuatan komposit dilakukan dengan variasi perbandingan serbuk gergaji dan abu sekam padi, kemudian dipilih komposisi terbaik berdasarkan kekompakan struktur, daya rekat, dan ketahanan fisik. Komposit optimum selanjutnya dikarakterisasi melalui uji kadar air, daya serap air, ketahanan komposit terhadap benturan, serta uji pelepasan amonia menggunakan spektrofotometri UV-Vis dengan reagen Nessler. Hasil penelitian menunjukkan bahwa komposisi optimum yang diperoleh pada perbandingan serbuk gergaji dan abu sekam padi pada perbandingan 8:4 gram. Komposit yang dihasilkan memiliki kadar air rata-rata 2,22% , daya serap air 5,84 g, dan ketahanan komposit terhadap benturan sebesar 76,19% , yang menunjukkan karakteristik fisik yang baik. Analisis spektrofotometri UV-Vis menunjukkan panjang gelombang optimum pada 429 nm, persamaan kurva kalibrasi y = 0,2252x-1,023 dengan nilai R² = 0,9602, serta waktu optimum analisis selama 140 menit . Hasil uji pelepasan amonia menunjukkan bahwa komposit urea melepaskan amonia lebih lambat dibandingkan urea tanpa lapisan, sehingga matriks sponge loofah, serbuk gergaji, abu sekam padi, dan lapisan tepung tapioka mampu menghambat pelepasan nitrogen secara bertahap. Dengan demikian, komposit yang dihasilkan berpotensi dikembangkan sebagai pupuk slow release yang lebih efisien dan ramah lingkungan.
Kata kunci: Pupuk slow release,urea, sponge loofah, abu sekam padi, serbuk gergaji, pelepasan amonia, spektrofotometri UV-Vis.

Putri Cut Habibi. (2026). Making Slow Release Urea Composite that can Act as a Dual Role as Fertilizer and Water Storage Planting Medium. [Undergraduate thesis.Universitas Syiah Kuala]. Under the supervision of Prof. Dr. Adlim, M.Sc., and Drs. Rusman, M.Si. Urea fertilizer is a widely used nitrogen source in crop cultivation; however, its utilization efficiency is relatively low because the nitrogen resulting from urea hydrolysis is easily lost through denitrification, leaching, and ammonia volatilization before the plants can optimally absorb it. One approach to improving urea use efficiency is the development of slow-release fertilizers (SRF). This study aimed to determine the optimal composition of an SRF urea fertilizer made from loofah sponge, sawdust, and rice husk ash, to assess the composite's physical characteristics, and to monitor ammonia release as an indicator of nitrogen release. Composites were prepared using varying ratios of sawdust to rice husk ash, and the best composition was selected based on structural compactness, adhesion, and physical durability. The optimal composite was further characterized through tests for moisture content, water absorption capacity, impact resistance, and ammonia release using UV-Vis spectrophotometry with Nessler's reagent. The results indicated that the optimal composition was achieved with a sawdust-to-rice husk ash ratio of 8:4 grams. The resulting composite exhibited an average moisture content of 2.22%, a water absorption capacity of 5.84 g, and an impact resistance of 76.19%, demonstrating favorable physical characteristics. UV-Vis spectrophotometric analysis revealed an optimal wavelength of 429 nm, a calibration curve equation of y = 0.2252x - 1.023 (R² = 0.9602), and an optimal analysis time of 140 minutes. Ammonia release tests showed that the urea composite released ammonia more slowly than uncoated urea, indicating that the matrix—comprising loofah sponge, sawdust, rice husk ash, and a tapioca starch coating—effectively retarded nitrogen release, allowing for a gradual release process. Consequently, the resulting composite holds potential for development into a more efficient and environmentally friendly slow-release fertilizer. Keywords: slow release fertilizer, urea, loofah sponge, rice husk ash, sawdust, ammonia release, UV-Vis spectrophotometry