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: Kualitas Bio-Slurry Campuran Rumen dan Darah Sapi Sebagai  Pupuk Cair Pada Tanaman Bayam (Amaranthus sp)
Abstrak: Bio-Slurry atau limbah biogas merupakan produk dari hasil pengolahan biogas berbahan campuran limbah ternak, proses pengolahannya dengan cara mencampur limbah ternak dengan air secara anaerob. Penelitian ini bertujuan menganalisis kualitas pupuk cair hasil samping pembuatan biogas dari campuran rumen dan darah sapi serta menganalisis efektivitasnya pada bayam hijau (Amaranthus sp) dengan konsentrasi berbeda. Rancangan percobaan yang digunakan adalah Rancangan Acak Lengkap (RAL) dengan enam perlakuan, P0 (pupuk cair komersial 300 ml. polybag-1 dan pupuk anorganik (150 kg ha-1 urea, 100 kg ha-1 SP-36, 100 kg ha-1 KCl)), P1 (pupuk cair komersial 150 ml. polybag-1 dan pupuk anorganik (75 kg ha-1 urea, 50 kg ha-1 SP-36, 50 kg ha-1 KCl)), P2 (pupuk Bio-Slurry cair A 300 ml. polybag-1 dan pupuk anorganik (150 kg ha-1 urea, 100 kg ha-1 SP-36, 100 kg ha-1 KCl)). P3 (pupuk Bio-Slurry cair B 300 ml. polybag-1 dan pupuk anorganik (150 kg ha-1 urea, 100 kg ha-1 SP-36, 100 kg ha-1 KCl)). P4 (pupuk Bio-Slurry cair C 300 ml. polybag-1 dan pupuk anorganik (150 kg ha-1 urea, 100 kg ha-1 SP-36, 100 kg ha-1 KCl)) masing-masing dengan tiga kali pengulangan. Hasil penelitian menunjukan bahwa pupuk Bio-Slurry cair terbaik yang digunakan dalam penelitian ini yaitu pupuk Bio-Slurry cair C, namun tingkat efektivitas pada tanaman bayam hijau (Amaranthus sp.) belum bisa menggantikan pupuk cair komersial dosis 100% tetapi memiliki hasil yang sama dengan pemberian pupuk komersial setengah dosis., Bio-Slurry or biogas waste is a product of biogas processing made from a mixture of slag waste, the processing process is by anaerobically mixing livestock waste with water. This study aims to analyze the quality of liquid fertilizer by product of making biogas from a mixture of rumen and cow's blood and analyze its effectiveness on green spinach (Amaranthus sp) with different concentrations. The experimental design used was a completely randomized design (CRD) with six treatments, P0 (commercial liquid fertilizer 300 ml. polybag-1 and inorganic fertilizer (150 kg ha-1 urea, 100 kg ha-1 SP-36, 100 kg ha-1 1 KCl)), P1 (commercial liquid fertilizer 150 ml. polybag-1 and inorganic fertilizer (75 kg ha-1 urea, 50 kg ha-1 SP-36, 50 kg ha-1 KCl)), P2 (Bio-fertilizer Liquid slurry A 300 ml polybag-1 and inorganic fertilizer (150 kg ha-1 urea, 100 kg ha-1 SP-36, 100 kg ha 1 KCl)). P3 (Liquid Bio-Slurry fertilizer B 300 ml. polybag-1 and inorganic fertilizer (150 kg ha-1 urea, 100 kg ha-1 SP-36, 100 kg ha-1 KCl)). P4 (Liquid Bio Slurry fertilizer C 300 ml. polybag-1 and inorganic fertilizer (150 kg ha-1 urea, 100 kg ha-1 SP-36, 100 kg ha-1 KCl)) each with three repetitions. The results showed that the best liquid Bio-Slurry fertilizer used in this study was liquid Bio-Slurry C fertilizer, but the level of effectiveness on green spinach (Amaranthus sp.) has not been able to replace 100% commercial liquid fertilizer but has the same results as half dose of commercial fertilizer.
Keyword: bio-slurry, green spinach, liquid fertilizer

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.
Keyword: