Judul: Effect of Growing Media and Fertilizer Dosage on Growth and Production of Green Beans (Phaseolus vulgaris L.)
Abstrak: Tanaman buncis dapat dibudidayakan di lahan maupun pekarangan dengan menggunakan pot atau polybag. Permasalahan budidaya buncis dengan menggunakan pot adalah rendahnya kandungan unsur hara pada media tumbuh tanaman (MTT). Upaya meningkatkan unsur hara dengan aplikasi pemupukan pada MTT sering menyebabkan terjadinya lonjakan daya hantar listrik (DHL) sehingga serapan hara menjadi terganggu. Zeoponik merupakan salah satu MTT berbahan zeolit yang memiliki KTK dan daya sangga terhadap DHL tinggi. Penelitian ini bertujuan mengetahui perbedaan pengaruh MTT zeoponik dan MTT komersial, serta dosis pupuk NPK yang ditambahkan terhadap pertumbuhan dan produksi tanaman buncis. Penelitian dilaksanakan di Fakultas Pertanian, IPB University. Percobaan dilakukan dengan model Rancangan Acak Lengkap (RAL) 2 faktor, yaitu jenis MTT dan dosis pupuk. Jenis MTT yang digunakan, yaitu zeoponik, media tanam A, dan media tanam B. Dosis pupuk NPK yang ditambahkan terdiri atas tiga taraf, yaitu 0 g/kg MTT, 1 g/kg MTT, dan 1.5 g/kg MTT. Parameter yang diamati, yaitu tinggi tanaman, jumlah daun, bobot polong, dan panjang polong. Analisis MTT yang dilakukan, yaitu pH, DHL, C-organik, N-tersedia, P-tersedia, P-total, basa-basa dapat dipertukarkan, dan unsur mikro. Berdasarkan penelitian, jenis MTT berpengaruh terhadap DHL, C-organik, P-tersedia, basa-basa dapat dipertukarkan, dan unsur mikro (Cu dan Zn). Dosis pupuk berpengaruh terhadap N-tersedia (NH4 + dan NO3 - ) dan P-total, sedangkan interaksi jenis MTT dan dosis pupuk berpengaruh terhadap kandungan NO3 - . MTT Zeoponik dapat mempertahankan pH netral, DHL rendah, dan kandungan K-dd, Ca-dd, serta Na-dd tinggi. MTT zeoponik menunjukkan pertumbuhan dan produksi tanaman buncis lebih baik dari MTT komersial A dan B. Media zeoponik dengan penambahan dosis pupuk NPK 1 g/kg menghasilkan pertumbuhan tanaman, bobot polong, dan panjang polong tertinggi.
Keyword: green beans, growing media, fertilizer, zeoponic

Judul: The Growth Response of Green Beans (Phaseolus  vulgaris L.) on Various Growing Media and Dose of NPK Fertilizer
Abstrak: Various plant growing media (PGM) were developed as an alternative to the issues of limited crop land available to support plant growth well enough so that it can produce the expected production. Proper PGM should be able to maintain the availability of water, oxygen and essential nutrients for plants. Fertilization to supply plant nutrients are often followed by increases the value of electrical conductivity (EC). Zeoponic that made up of zeolites, cocopeats, and compost had high cation exchange capacity (CEC) and good buffer capability against the increasing of EC due to the fertilization. This study was aimed to determine the effect of PGM and dose of fertilizer application on the chemical properties of PGM, growth and production of green beans (Phaseolus vulgaris L). The NPK fertilizer experiments on green beans were in two different types of media with factorial completely randomized design (CRD) which were zeoponics and nonzeoponics, as well as four levels fertilization doses (0, 1, 2, and 3 g kg-1 ). Plants respond to the treatments variously. The usage of both PGM took a significant effect in pH, EC, nitrogen (available-N), phosphorus (available-P and total-P), CEC, cation bases (Ca, Mg, K, Na), base saturation, organic-C, micro nutrients (Fe, Cu, Zn, Mn) in media, plant height, and the number of plant leaves. The treatment of fertilizer doses significantly effected organic-C, available-N, height of plant, the number of plant leaves, the weight of bean, the wet and dry weight of plant. Generally, growth and production of green beans in zeoponic media were faster than in nonzeoponics. The best results were in the treatment of Z2 (zeoponic + NPK fertilizer 2 g kg-1 ) with the weight of green beans (120,47 g), the dry weight of plant (14,48 g), the height (76,02 cm) and number of plant leaves (29 leaves).
Keyword: fertilization, horticulture, zeolite, zeoponik

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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