Judul: Pengaruh pupuk organik pada produksi dan serapan hara tanaman Caisim (Brassica juncea) varietas Tosakan pada Latosol Darmaga
Abstrak: Indonesian lands are dominated by acid soils and generally have low soil fertility due to tropical high rainfall that resulted in highly leaching and weathering. One of ways to improve soil fertility is by using fertilizer. Application of organic fertilizer are able to increase soil properties such as increasing soil nutrients, organic carbon and soil CEC which will provide soil nutrients and increase the efficiency of fertilizer. This research aims to evaluate the effect of organic fertilizer to the yield, nutrient content and uptake of the leaf caisim (Brassica juncea) on Latosol Darmaga and also to calculate the farming R/C (Revenue Cost Ratio) analysis. The Research was conducted in the field of University Farm Cikabayan, Bogor. Fertilizer that used in this research were organic fertilizer (OF) and standard (S). The form of organic fertilizer were granule and recommendation of the dose was 2 ton/ha. Then, standard was a conventional recommendation used for Caisim, there were 200 kg urea/ha, 300 kg SP-36/ha and 100 kg KCl/ha. Plant analysis was conducted in Chemical and Soil Fertility Laboratory, Faculty of Agriculture, IPB. This research design was Randomize Complete Block Design (RCBD) with 7 doses of treatment and 4 replication, so that there were 28 experimental units. The treatments were : Control, Standard (S), 75% OF + 50% S, 75% OF + 75% S, 100% OF + 50% S, 100% OF +75% S, and 125% OF + 50% S. The result showed that combination of organic fertilizer with standard fertilizer, and standard fertilizer only significantly have higher yield compared with control in parameters such as plant weight, leaf nutrient content (P) and leaf uptake (N, P and K). Additional of organic fertilizer improved effectivity of fertilizer to yield because organic fertilizer with additional of standard fertilizer in lower dose (50% and 75%) were able to produce higher number of plant/plot than standard fertilizer treatment only. Economic farming analysis indicated that combination organic and standard fertilizer were profitable economically. The highest value for parameters such as production, nutrient content, nutrient uptake and R/C ratio occurred in 75%PO + 75%S and 100%PO and 75%S.
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: