Judul: Pengaruh Populasi Cacing Eisenia Foetida Dan Waktu Pemberian Pupuk Kandang Terhadap Produktivitas Dan Kualitas Sorgum (Sorghum Bicolor).
Abstrak: Peranan cacing tanah sangat penting dalam proses dekomposisi bahan organik tanah. Perombakan bahan organik dapat menghasilkan unsur hara yang dibutuhkan tanaman untuk pertumbuhannya. Penelitian ini dilakukan sebagai studi dasar untuk mengevaluasi tentang produktivitas dan kualitas tanaman Sorghum bicolor (L.) Moench dengan perlakuan pemberian populasi cacing tanah E. foetida dan waktu pemberian pupuk kandang. Penelitian ini menggunakan rancangan acak lengkap berpola faktorial 2x4 dengan 3 ulangan. Peubah yang diamati yaitu tinggi tanaman, jumlah daun, berat segar, berat kering, kualitas mineral meliputi N (nitrogen), P (fosfor), K (kalium), jumlah cacing dan kokon saat panen. Hasil penelitian menunjukkan bahwa perlakuan populasi cacing 50 ekor secara nyata (P<0.05) meningkatkan produktivitas, namun tidak meningkatkan kualitas nutrisi tanaman Sorghum bicolor, sedangkan waktu pemberian pupuk kandang tidak memberikan pengaruh nyata pada kualitas nutrisi tanaman Sorghum bicolor.
Keyword: cacing tanah Eisenia foetida, pupuk kandang, Sorghum bicolor L, Moench

Judul: Pengaruh Populasi Cacing Tanah Eisenia foetida, Pupuk NPK dan Kapur terhadap Produktivitas dan Kualitas Sorgum (Sorghum bicolor L. Moench) Varietas Numbu pada Latosol Dramaga
Abstrak: Eisenia foetida is known as potential earthworm to reorganize the organic matter into inorganic matter that are beneficial to plants. This research aimed to determine the influence of population of earthworm E. foetida, NPK fertilizer and lime to productivity and nutritional quality of sorghum (Sorghum bicolor L. Moench) in Latosol Dramaga. The observed variables were the vertical height of plants, number of leaves, fresh weight, dry matter, crude protein, crude fiber and content of calcium. This research used factorial completely randomized design 2x2x3 with 3 replications. The results showed that the combination NPK fertilizer and earthworm significantly (P<0.05) increased the productivity of the plant. The Quality of nutrition, crude protein and calcium (Ca), significantly increased (P<0.05) and respectively influenced by NPK fertilizer and lime. Whereas the crude fiber, very markedly decreased (P<0.01) in influenced by the interaction between NPK fertilizers and earthworm.
Keyword: Sorghum bicolor L. Moench,, NPK fertilizer, lime, latosol, Earthworm Eisenia foetida

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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