Judul: Increasing the Carrying Capacity of Post-Coal Mining Grazing Fields with Different Doses of Urea Fertilization
Abstrak: Penelitian ini bertujuan mengetahui pengaruh dosis pemupukan urea dan pemotongan yang berbeda terhadap pertumbuhan dan produktifitas rumput Brachiaria decumbens dalam meningkatkan kapasitas tampung di padang penggembalaan lahan pasca tambang batu bara. Penelitian menggunakan rancangan acak kelompok faktorial (RAKF) dengan dua faktor yaitu faktor A terdiri dari T1 = Pemotongan 5 cm dari permukaan tanah; T2 = Pemotongan 10 cm dari permukaan tanah. Faktor B terdiri dari P0 = Kontrol; P1 = Urea 100 kg ha-1; P2 = Urea 200 kg ha-1; P3 = Urea 300 kg ha-1. Parameter yang diuji adalah komposisi botani, kapasitas tampung existing dan peningkatannya, Proper Use Factor (PUF), produksi protein, tinggi, diameter, dan biomassa tanaman. Hasil penelitian kapasitas tampung existing sebesar 1,01 ST ha-1. Pemupukan urea berpengaruh terhadap diameter, biomassa tanaman, peningkatan kapasitas tampung dan produksi protein. Perlakuan T2 dan P2 efektif menghasilkan nilai PUF sebesar 66,30% dan meningkatkan kapasitas tampung menjadi 1,70 ST ha-1., This research aimed to determine the effect of different doses of urea fertilization and mowing on the growth and productivity of Brachiaria decumbens grass in increasing carrying capacity in pastures on post-coal mining land. The research used a randomized block factorial design (RBFD) with two factors, namely factor A consisting of T1 = Cutting 5 cm from the ground surface; and T2 = Cutting 10 cm from the ground surface. Factor B consists of P0 = Control; P1 = Urea 100 kg ha-1; P2 = Urea 200 kg ha-1; P3 = Urea 300 kg ha-1. The parameters tested were botanical composition, existing and increasing capacity, Proper Use Factor (PUF), protein production, height, diameter, and plant biomass. The research results showed that the existing carrying capacity is 1.01 AU ha-1. Urea fertilization affected diameter, plant biomass, increased carrying capacity, and protein production. Treatment of T2 and P2 was effective in produced a PUF value by 66.30% and increased the carrying capacity to 1.70 AU ha-1.
Keyword: botanical composition, carrying capacity, Proper Use Factor, urea fertilizer

Judul: Optimization of Chicken Manure Fertilizer (Broiler) in  Supporting Productivity of Brachiaria humidicola in Jonggol Animal Science  Teaching and Research Unit (JASTRU)
Abstrak: Penelitian ini bertujuan untuk mengukur dosis pupuk kandang ayam yang memberikan hasil yang terbaik terhadap produktivitas rumput Brachiaria humidicola. Penelitian ini dilaksanakan di Unit Pendidikan dan Penelitian Peternakan Jonggol (UP3J). Penelitian dilakukan dengan menggunakan rancangan acak lengkap dengan pola petak terbagi (RAL split plot) dengan 5 perlakuan dan 4 ulangan, yaitu P1 = urea 150 kg ha-1, P2 = 5 ton ha-1 pupuk kandang ayam + urea 75 kg ha-1, P3 = 10 ton ha-1 pupuk kandang ayam + urea 75 kg ha-1, P4 = 15 ton ha-1 pupuk kandang ayam + urea 75 kg ha-1 dan P5 = 20 ton ha-1 pupuk kandang ayam + urea 75 kg ha-1. Hasil penelitian menunjukkan pupuk kandang ayam efektif meningkatkan jumlah tunas, jumlah stolon, panjang stolon, tinggi tanaman, produksi biomassa individu tanaman, warna tanah serta warna daun rumput Brachiaria humidicola. Dosis optimal dalam mendukung produktivitas rumput Brachiaria humidicola sebesar 20 ton ha-1 pupuk kandang ayam dan 75 kg ha-1 pupuk anorganik urea. Peningkatan dosis pupuk kandang ayam berkorelasi positif terhadap produksi biomassa rumput Brachiaria humidicola., The aim of this research were to measure the dose of chicken manure fertilizer that gives the best results on the productivity of Brachiaria humidicola. These experiment were conducted at Jonggol Animal Science Teaching and Research Unit (JASTRU). This research was designed by using split-plot design with 5 treatments and 4 replications, namely P1 = urea 150 kg ha-1, P2 = 5 tons ha-1 of chicken manure fertilizer + urea 75 kg ha-1, P3 = 10 tons ha-1 of chicken manure fertilizer + urea 75 kg ha-1, P4 = 15 tons ha-1 of chicken manure fertilizer + urea 75 kg ha-1 and P5 = 20 tons ha-1 of chicken manure fertilizer + urea 75 kg ha-1. The results showed that chicken manure fertilizer was effective in increasing the number of shoots, number of stolons, stolon length, plant height, individual plant biomass production, soil color and leaf color of Brachiaria humidicola. The optimal dose to support the productivity of Brachiaria humidicola is 20 tons ha-1 of chicken manure fertilizer and 75 kg ha-1 of urea. Increasing the dose of chicken manure fertilizer was positively correlated to the biomass production of Brachiaria humidicola.
Keyword: Brachiaria humidicola, chicken manure fertilizer, productivity, UP3J

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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