Judul: The Effect of Organic Fertilizer “Phosta” and Mineral Fertilizer Against Production and Nutrien Uptake of Caisin in Latosol Darmaga.
Abstrak: Kesuburan Latosol pada umumnya rendah karena mempunyai kandungan bahan organik dan ketersediaan hara yang rendah. Salah satu cara untuk mengatasi permasalahan kesuburan Latosol adalah dengan pemberian pupuk, baik pupuk organik maupun pupuk anorganik. Pemupukan dilakukan karena tanah tidak mampu menyediakan hara dalam jumlah yang cukup untuk kebutuhan tanaman. Percobaan ini dilaksanakan dari bulan Februari sampai Mei 2011 di lahan kebun percobaan IPB Cikabayan, Darmaga, Bogor. Analisis tanah dan tanaman dilakukan di Laboratorium Kimia dan Kesuburan Tanah, Departemen Ilmu Tanah dan Sumberdaya Lahan, Fakultas Pertanian, Institut Pertanian Bogor. Tujuan dari penelitian ini adalah untuk mengetahui pengaruh pupuk organik “PhOSta” dan pupuk mineral pada produksi dan serapan hara Caisin varietas Tosakan pada Latosol Darmaga. Rancangan percobaan yang digunakan adalah Rancangan Acak Kelompok (RAK) yang terdiri dari 11 perlakuan, dan setiap perlakuan diulang sebanyak tiga kali sehingga terdapat 33 petak percobaan. Sebelas perlakuan tersebut terdiri dari: Kontrol, 0P + 1/3 STD, 0P + 2/3 STD, OP + 1 STD (Pupuk standar), 1P + O STD, 1P + 1/3 STD, 1P + 2/3 STD, 2P + O STD, 2P + 1/3 STD, 2P + 2/3 STD, dan 3P + O STD. Pemberian pupuk organik “PhOSta” disertai dengan pupuk mineral dengan dosis standar berpengaruh nyata terhadap produksi dan serapan hara Caisin varietas Tosakan. Perlakuan 0 P + 1 STD (perlakuan standar) memiliki peningkatan paling tinggi untuk semua parameter pengamatan. Pupuk organik “PhOSta” yang diberikan tanpa penambahan pupuk mineral tidak memberikan dampak positif bagi tanaman yang terlihat pada perlakuan 1 P + 0 STD, 2 P + 0 STD, dan 3 P + 0 STD. Jika dilihat dari uji lanjut RAE bobot basah Caisin per petak, antara perlakuan 0 P + 1 STD (perlakuan standar) dengan perlakuan 0 P + 1/3 STD, 0 P + 2/3 STD, 1 P + 1/3 STD, 1 P + 2/3 STD, 2 P + 1/3 STD, dan 2 P + 2/3 STD menunjukkan hasil yang tidak berbeda nyata.
Keyword: 

Judul: Uji efektivitas pupuk organik cair terhadap produksi dan serapan hara tanaman Caisim (Brassica juncea) varietas Tosakan pada Latosol Darmaga
Abstrak: Latosol fertility is generally low because of its low organic matter content and nutrient availability. One of many ways to overcome the low fertility of Latosol is adding fertilizers, either organic or inorganic fertilizers. Fertilization can be applied through the soil or plants. Fertilizer that applied through the plants is usually provided by liquid fertilizer which sprayed on the plant leaf. This experiment was conducted from January to May 2010 in greenhouse located in Cikabayan, IPB. Soil and plant analysis were conducted at the Laboratory of Chemistry and Soil Fertility, Department of Soil Science and Land Resources, Faculty of Agriculture, Bogor Agricultural University. The purpose of to test the effectiveness of liquid organic fertilizer to the growth of caisim plants (Brassica juncea), Tosakan variety in Latosol Darmaga. The experiment design using Completely Randomized Design (CRD) comprised of seven treatments with five replications. Treatments consisted of no fertilizer added (Control), 100% chemical or standard fertilizer (PS), 75% liquid organic fertilizer (PO) + 50% PS, 75% PO + 75% PS, 100% PO + 50% PS, 100% PO + 75% PS, and 125% PO + 50% PS. The results showed that the effect of chemical (standard) fertilizer or a combination of chemical fertilizer and liquid organic fertilizer on the growth parameters (weight of fresh leaves and weight of dry leaves), leaf nutrient content (N and K), P nutrient content of root and nutrient uptake (N, P, and K) , and RAE value were significantly higher than control. Generally, liquid organic fertilizer showed the effectiveness if it was combined with chemical fertilizer of its lower rate (75%). It was the most effective fertilizer combination than other treatments.
Keyword: 

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: