Judul: Pembuatan Pupuk Urea Bersalut Gibsum (Gypsum Coated Urea, GCU) dan Pengaruhnya terhadap Pertumbuhan Jagung (Zea mays).
Abstrak: Urea (CO(NH2)2) merupakan jenis pupuk nitrogen yang paling banyak ditemui dipasaran dan digunakan oleh petani di Indonesia. Sifat higroskopis yang dimiliki oleh pupuk urea menyebabkan pupuk ini mudah larut dalam air dan mudah tercuci keluar dari sistem tanah, akibatnya pemupukan menjadi sangat tidak efisien. Salah satu upaya untuk mengurangi kehilangan N akibat pencucian yaitu dengan memodifikasi sifat fisik pupuk urea dengan mengubah menjadi pupuk lambat tersedia (slow release). Halangan fisik pada pupuk slow release, dapat digunakan untuk memperlambat interaksi antara pupuk urea dengan air sehingga urea akan lebih tahan pelarutan oleh air dan mengurangi kehilangan N melalui pencucian. Tujuan penelitian ini adalah : (1) Membuat pupuk urea bersalut gibsum (Gypsum Coated Urea, GCU), (2) Mengukur konsentrasi N-NH4 + dan N-NO3 - dari pupuk GCU pada percobaan pencucian, (3) Menentukan pengaruh pupuk GCU terhadap pertumbuhan dan serapan nitrogen, serta kalsium pada jagung. Hasil penelitian menunjukkan bahwa diperoleh empat jenis pupuk GCU berbentuk granul ukuran 3-5 mm dengan kandungan nitrogen sebesar 33.36% (S1) , 30.97% (S2), 31.51% (M1), dan 29.73% (M2). Empat jenis pupuk tersebut berkarakter sebagai slow release karena dapat mengurangi pencucian nitrogen dalam bentuk ammonium dan nitrat. Berdasarkan data pertumbuhan dan analisis serapan hara tanaman menunjukkan bahwa bentuk slow release yang diperoleh berpengaruh nyata terhadap pertumbuhan tinggi jagung pada 2 hingga 5 minggu setelah tanam.
Keyword: kehilangan nitrogen, pencucian, pupuk lambat tersedia

Judul: Formulasi Pupuk Nitrogen Lambat Tersedia dari Bahan Urea, Zeolit, dan Asam Humat serta Pengaruhnya terhadap Pertumbuhan Jagung
Abstrak: The quality of agricultural land in Indonesia was declining progressively and it affect to the decrease of crop production. It is well known that N fertilizer is inefficient due to evaporation into atmosphere and leached into the grown water. The objectives of this research were to study the formulation of slow release N-fertilizer made from urea, zeolite, humic acid, and polymer; to study the pattern of nitrogen release from this modified slow release fertilizer; and to evaluate the effect of modified slow release fertilizer on corn growth. The ratio of urea and zeolite used in this experiment was prepared with the ratio of urea (U) and zeolite (Z) 7:3 and 8: 2, humic acid (HA) of 2 and 2.5% and arabic gum as the binding material. The modified fertilizers were put into the percolation column. The volume and concentration of ammonium-N and nitrate-N were collected and measured during one month percolation with Kjeldahl methode. The modified fertilizers then used to evaluate the effect of the fertilizers on growth of corn in greenhouse experiment. The results showed that the composition of the six N fertilizer were prepared by coating with zeolite, humic substance, and gum arabic characterized as a slow release fertilizer. Zeolite, humic substance, and gum arabic or combinations there of as coating agent is able to reduce the peak release of N-NH4+ and N-NO3- and change the pattern of release to be still available until the end of the test period. Based on the data of corn’s growth, slow release fertilizer forms obtained did not match the corn crop N requirement in accordance with the physiological growth so that the best growth is obtained only by urea which has a high solubility. Humic substance influential in terms of the physiological properties of corn compared to its role as an encapsulation on slow release fertilizer.
Keyword: ammonium-N, humic acid, nitrate-N, slow release fertilizer, zeolite

Judul: Posisi Filogenetik Kura-Kura Carettochelys Insculpta  (Reptillia: Testudinata)
Abstrak: Carettochelys insculpta is an endemic freshwater turtle of southern Papua and northern Australia. Phylogenetic position of this turtle is remain unresolved until now. Most of the research conducted show close relationships of C. insculpta and members of Trionychidae family. However, some of the research show distance between C. insculpta and members of Trionychidae family. This research is conducted to analyze phylogenetic relationship between C. insculpta and other members of Testudinata using 12S rRNA, 16S rRNA, and both gene as markers. DNA samples were obtained from three different organisms of C. insculpta. Two species used as outgroups were Alligator mississippiensis and Iguana iguana. Phylogenetic analysis was carried out using Neighbor-Joining method with Felsenstein 1981 (F81) modeltest. A polytomy tree of Testudinata was produced by using 12S rRNA gene. However, analysis using 16S rRNA and both genes as markers confirmed that C. insculpta was located between the Chelonidae and the Trionychidae family.
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