Judul: Effect of Biogas Waste Sludge Mixed Cow Feces and Odot Grass (Pennisetum purpureum cv. Mott) on Growth and Production of Green Spinach (Amaranthus gangeticus)
Abstrak: Limbah kotoran ternak (feces) bisa dimanfaatkan sebagai pembuatan biogas. Produksi biogas menghasilkan gas dan hasil sampingan yang dapat dijadikan pupuk untuk tanaman. Penelitian bertujuan menganalisis dan mengetahui pengaruh lumpur limbah biogas campuran kotoran sapi dan rumput odot (Pennisetum purpureum cv. Mott) terhadap pertumbuhan dan produksi tanaman bayam hijau (Amaranthus gangeticus). Prosedur yang digunakan yaitu analisis kimia kandungan dalam sludge dan analisis data menggunakan rancangan acak lengkap (RAL) pada uji tanam. Perlakuan pertama merupakan kontrol yaitu 5 kg tanah latosol, perlakuan kedua merupakan campuran 4 kg tanah latosol dan 1 kg sludge, perlakuan ketiga merupakan 4,975 kg tanah latosol dan pupuk NPK (16-16-16) 25 gram. Kombinasi perlakuan terbaik yang diperoleh adalah perlakuan pertama campuran 4 kg tanah latosol dan 1 kg sludge. Perlakuan pupuk organik perlakuan pertama yaitu campuran 4 kg tanah latosol dan 1 kg sludge untuk meningkatkan pertumbuhan vegetatif tanaman yang meliputi tinggi tanaman, jumlah daun, lebar daun, diameter batang, berat segar, berat kering, dan kandungan bahan kering tanaman bayam hijau., Livestock manure (feces) can be used as biogas. Biogas production produces gas and by-products that can be used as fertilizers for plants. The aims of research is to analyze and determine the effect of biogas waste sludge mixed with cow dung and odot grass (Pennisetum purpureum cv. Mott) on the growth and production of green spinach (Amaranthus gangeticus). The procedure used is chemical analysis of the content in the sludge and data analysis using a Completely Randomized Design (CRD) in the planting test. The first treatment was a control, namely 5 kg of latosol soil, the second treatment was a mixture of 4 kg of latosol soil and 1 kg of sludge, the third treatment was 4.975 kg of latosol soil and 25 grams of NPK fertilizer (16-16-16). The best treatment combination obtained was the first treatment with a mixture of 4 kg of latosol soil and 1 kg of sludge. The first treatment of organic fertilizer was a mixture of 4 kg of latosol soil and 1 kg of sludge to increase plant vegetative growth which included plant height, number of leaves, leaf width, stem diameter, fresh weight, dry weight, and dry matter content of green spinach plants.
Keyword: completely randomized design, odot grass, organic fertilizer, sludge

Judul: The Quality Testing of Bio-slurry Solid Fertilizer Mixed Rumen Contents and Cow's Blood on Productivity of Spinach Plant
Abstrak: Pemanfaatannya untuk biogas berupa bio-slurry yang potensial sebagai pupuk organik. Penelitian ini bertujuan untuk mengetahui kualitas pupuk padat dari bio-slurry campuran isi rumen sapi dan darah sapi pada produktivitas tanaman bayam hijau. Penelitian di design dengan rancangan acak lengkap (RAL) yang terdiri dari 5 perlakuan dan 5 pengulangan, yaitu P0 (pupuk padat komersial 10 ton. ha−1 polybag-1 dan pupuk anorganik (0.25 ton. ha−1 Urea, 0.1 ton. ha−1 SP-36 dan 0.15 ton. ha−1 KCl)), P1 (pupuk padat komersial 5 ton. ha−1 polybag-1 dan pupuk anorganik (0.25 ton. ha−1 Urea, 0.1 ton. ha−1 SP-36 dan 0.15 ton. ha−1 KCl)), P2 (pupuk bio-slurry A 10 ton. ha−1 polybag-1 dan pupuk anorganik (0.25 ton. ha−1 Urea, 0.1 ton. ha−1 SP-36 dan 0.15 ton. ha−1 KCl)), P3 (pupuk bio-slurry B 10 ton. ha−1 polybag-1 dan pupuk anorganik (0.25 ton. ha−1 Urea, 0.1 ton. ha−1 SP-36 dan 0.15 ton. ha−1 KCl)), dan P4 (pupuk bio-slurry C 10 ton. ha−1 polybag-1 dan pupuk anorganik (0.25 ton. ha−1 Urea, 0.1 ton. ha−1 SP-36 dan 0.15 ton. ha−1 KCl)). Hasil penelitian menunjukan jika pupuk bio-slurry A (100% isi rumen sapi) memiliki hasil yang tidak berbeda jauh dengan pupuk padat komersial setengah dosis tetapi tidak dapat menggantikan efektivitas pupuk padat komersial., Its utilization for biogas produces bio-slurry which has the potential as organic fertilizer. The study is about determine the quality of solid fertilizer from bio-slurry a mixture of cow rumen contents and cow blood on the productivity of green spinach. The study was designed with completely randomized design (CRD) consisting of 5 treatments and repetition, namely P0 (commercial solid fertilizer 10 ton. ha−1 polybag-1 and anorganic fertilizer (0.25 ton. ha−1 Urea, 0.1 ton. ha−1 SP-36 dan 0.15 ton. ha−1 KCl)), P1 (commercial solid fertilizer 5 ton. ha−1 polybag-1 and anorganic fertilizer (0.25 ton. ha−1 Urea, 0.1 ton. ha−1 SP-36 dan 0.15 ton. ha−1 KCl, P2 (fertilizer bio-slurry A 10 ton. ha−1 polybag-1 and anorganic fertilizer (0.25 ton. ha−1 Urea, 0.1 ton. ha−1 SP-36 dan 0.15 ton. ha−1 KCl)), P3 (fertilizer bio-slurry B 10 ton. ha−1 polybag-1 and anorganic fertilizer (0.25 ton. ha−1 Urea, 0.1 ton. ha−1 SP-36 dan 0.15 ton. ha−1 KCl)), dan P4 (fertilizer bio-slurry C 10 ton. ha−1 polybag-1 and anorganic fertilizer (0.25 ton. ha−1 Urea, 0.1 ton. ha−1 SP-36 dan 0.15 ton. ha−1 KCl). The results showed that bio-slurry A (100% rumen of cow) has results don’t have much different from half-dose commercial solid fertilizer but cant replace it.
Keyword: Bio-Slurry, Solid Fertilizer, Spinach

Judul: Hamiltonian formulation for linear waves motion in two layers fluid
Abstrak: The surface wave could be considered as a wave that separates two fluids, namely water and air. Based on this assumption, it is introduced the interfacial wave, a wave between two layers of fluid with different density. The formulation of interfacial waves motion begins with deriving the base equation of irrotational ideal fluid. Furthermore, according to irrotational fluid assumption, the base equation can be stated in velocity potential. In this derivation, the fluids domain is assumed to be restricted by rigid lid boundary conditions, both at the upper and lower limit. Therefore, the interfacial waves motion can be explained in a hamiltonian formulation. In the hamiltonian formulation, total energy is defined as the sum of kinetic and potential energy. The hamiltonian system is obtained from reduction of kinetic energy by using the Dirichlet Neumann Operator. The resulted kinetic energy equation is nonlinear. Therefore, this form is linearized by first part of the Taylor expansion. This linearization gives a dispersion relation of linear wave. Based on this dispersion relation, the phase speed of the linear wave depends on the density ratio of the two layers fluid.
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