Judul: Pengaruh Terak Baja dan Bahan Organik terhadap Produksi dan Kadar Hara Tanaman Caisim (Brassica juncea L.) pada Latosol Darmaga
Abstrak: Latosol adalah tanah yang penyebarannya cukup luas dan menempati area sekitar 9% dari daratan Indonesia. Pada umumnya Latosol mempunyai tingkat kesuburan yang rendah karena memiliki pH tanah masam, bahan organik dan kapasitas tukar kation (KTK) tergolong rendah. Hal ini mengakibatkan produksi tanaman umumnya rendah. Pengapuran dan penambahan bahan organik merupakan beberapa upaya untuk meningkatkan kesuburan tanah. Salah satu bahan yang dapat digunakan sebagai bahan kapur adalah terak baja. Material ini mengandung Ca, Mg, Fe, Mn, Si dan unsur-unsur lainnya. Selanjutnya, penambahan bahan organik berperan dalam memperbaiki sifat kimia, fisik maupun biologi tanah. Kandungan hara dalam terak baja dan peranan bahan organik diharapkan dapat memperbaiki kesuburan tanah dan meningkatkan produksi tanaman. Penelitian ini bertujuan untuk mempelajari pengaruh pemberian terak baja tanpa bahan organik (B0) atau yang dikombinasikan dengan bahan organik (B1) terhadap produksi tanaman caisim, kadar hara (N, P, K, Ca dan Mg) dan kadar logam berat (As, Pb, Sn, Cd dan Hg) daun tanaman caisim. Penelitian ini dilakukan di rumah kaca (University Farm IPB) dan Laboratorium Kimia dan Kesuburan Tanah, Departemen Ilmu Tanah dan Sumberdaya Lahan, IPB. Penelitian ini menggunakan Rancangan Acak Kelompok (RAK) faktorial 3 faktor dengan faktor utama adalah jenis terak baja yaitu Sj (terak baja Jepang) dan Si (terak baja Indonesia). Faktor kedua yaitu terak baja dengan 4 dosis (T0, T1, T2, T3). Untuk terak baja Jepang dosis diberikan setara 0, 5, 10, 15 ton/ha sedangkan terak baja Indonesia dosis diberikan setara 0, 4, 8, 12 ton/ha. Faktor ketiga adalah bahan organik, tanpa bahan organik (B0) dan dengan bahan organik (B1) setara dengan 10 ton/ha. Masing-masing perlakuan terdiri dari 4 ulangan sehingga terdapat 64 satuan percobaan. Pemberian terak baja (Jepang dan Indonesia) tanpa bahan organik (B0) meningkatkan produksi antara 169-250% sedangkan pemberian terak baja (Jepang dan Indonesia) yang dikombinasikan dengan bahan organik (B1) meningkatkan produksi antara 128-169%. Pemberian terak baja meningkatkan P dan Mg tetapi menurunkan N dan K pada daun caisim. Peningkatan P dan Mg terjadi karena peningkatan pH oleh adanya Ca dan Mg yang dilepaskan dari terak baja. Penurunan N dan K karena pada terak baja tidak mengandung unsur N dan hanya terdapat unsur K yang sangat kecil. Kadar As, Pb, Sn, Cd dan Hg tidak terukur pada daun caisim yang ditanam pada tanah yang diberikan terak baja. Namun demikian kadar Pb dan Sn terukur pada daun caisim dengan kadar masih di bawah ambang batas yang diperbolehkan (Badan Standarisasi Nasional, 2009).
Keyword: 

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: 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: