Judul: Effect of Nitrogen Addition in Zeoponic on  the Growth of Mustard Greens (Brassica juncea L.) and Pak choy (Brassica rapa L.)
Abstrak: Media tumbuh tanaman merupakan komponen penting dalam pertumbuhan dan perkembangan tanaman hortikultura. Zeoponik termasuk media tumbuh tanaman berbahan dasar zeolit yang dicampur dengan kompos, cocopeat, dan pupuk. Kelebihan dari zeoponik diantaranya memiliki kapasitas tukar kation (KTK) yang tinggi sehingga dapat mempertahankan nilai daya hantar listrik (DHL) agar tetap rendah. Pada kondisi kandungan unsur hara tinggi dan DHL rendah, tanaman akan dapat tumbuh dengan baik. Penelitian bertujuan mengetahui pengaruh penambahan nitrogen yang bersumber dari pupuk urea pada media zeoponik standar terhadap sifat-sifat kimia zeoponik dan pertumbuhan tanaman sawi hijau (Brassica juncea L.) serta pakcoy (Brassica rapa L.). Penelitian dilaksanakan di Rumah Kaca Cikabayan menggunakan model rancangan acak lengkap (RAL) faktor tunggal berupa dosis nitrogen yang ditambahkan ke dalam media zeoponik standar. Media ini mengandung pupuk NPK 1,5 g/liter dan pupuk mikro majemuk 0,5 mg/liter. Nitrogen diberikan dalam bentuk urea. Dosis nitrogen yang diujikan terdiri dari 4 taraf, yaitu 0 N; 1 N; 1,5 N; dan 2 N atau setara dengan 0; 0,52; 0,78; dan 1,04 gram urea, masing-masing per liter media (P0, P1, P2, dan P3). Parameter pertumbuhan yang diamati berupa tinggi tanaman, jumlah daun, panjang daun, lebar daun, dan kandungan klorofil daun. Hasil penelitian menunjukkan bahwa penambahan pupuk urea pada zeoponik standar akan menurunkan pH dan meningkatkan nilai DHL, kadar amonium serta nitrat. Media zeoponik standar memberikan hasil yang lebih baik dibandingkan dengan zeoponik yang diberi tambahan nitrogen pada setiap parameter pertumbuhan baik tanaman sawi (Brassica juncea L.) maupun pakcoy (Brassica rapa L.)., Plant growing media is an important component in the growth and development of horticultural crops. Zeoponic is a plant growing media made from zeolite which is mixed with compost, cocopeat, and fertilizer. The advantages of zeoponic include having a high cation exchange capacity (CEC) so that it can maintain low electrical conductivity (EC). In conditions of high nutrient content and low EC, plants will grow well. The aim of this study was to determine the effect of adding nitrogen to the standard zeoponic, on the zeoponic chemical properties and the growth of mustard greens (Brassica juncea L.) and pak choy (Brassica rapa L.). The study was conducted at the Cikabayan Greenhouse using a single factor completely randomized design (CRD) model in the form of a dose of nitrogen added to standard zeoponic media. This media contained 1,5 g/liter of NPK fertilizer and 0,5 mg/liter of micro compound fertilizer. Nitrogen was supplied in the form of urea. The tested nitrogen dose consisted of 4 levels, namely 0 N; 1 N; 1,5 N; and 2 N or equivalent to 0; 0,52; 0,78; and 1,04 grams of urea, each per liter of media (P0, P1, P2, and P3). The observed growth parameters were plant height, number of leaves, leaf length, leaf width, and leaf chlorophyllcontent. The results showed that the addition of urea fertilizer to the standard zeoponic would decrease the pH and increase the EC value, ammonium and nitrate levels. The standard zeoponic media gave better results compared to zeoponic which was given additional nitrogen in each growth parameter for both mustard greens (Brassica juncea L.) and pak choy (Brassica rapa
Keyword: amonium, nitrat, urea, zeolit

Judul: The Effect of Zeoponic media on Horticultural Plant Growth in Cisarua District Bogor
Abstrak: Kelemahan media tumbuh tanaman (MTT) saat ini yaitu melonjaknya nilai DHL pada saat dilakukan penambahan pupuk, sehingga diperlukan bahan yang memiliki KTK tinggi untuk mengatasinya. Zeoponik adalah MTT dengan bahan dasar zeolit yang dicampurkan dengan cocopeat dan kompos. Zeoponik memiliki KTK tinggi yang dapat mempertahankan DHL agar tetap rendah. Penelitian ini bertujuan mempelajari karakteristik kimia MTT zeoponik dan non zeoponik, dan pengaruhnya terhadap pertumbuhan tanaman sawi, tomat, dan terong. Rancangan acak lengkap (RAL) faktor tunggal digunakan untuk melihat pengaruh jenis MTT terhadap parameter pertumbuhan tanaman tinggi, jumlah, panjang dan lebar daun, diameter batang, bobot basah dan bobot kering umur 4MST pada sawi dan 5MST pada tomat dan terong. MTT yang digunakan yaitu zeoponik campuran dari zeolit, cocopeat dan kompos (2:1:1) dengan media pembanding non zeoponik campuran tanah subur dan pupuk organik matang (2:1). Analisis sifat kimia MTT dilakukan sebelum dan setelah tanam. Analisis kandungan unsur hara makro dan mikro dilakukan pada ketiga tanaman. Hasil penelitian menunjukkan media zeoponik memiliki keunggulan pH awal netral 6,7 dan pH akhir 6,8 – 7,0. Nilai DHL yang sesuai terhadap pertumbuhan tanaman sebesar 1,505 mS cm-1 sedangkan media non zeoponik memiliki DHL rendah 0,187 mS cm-1. Media zeoponik mengandung KTK tinggi sebesar 88,1 – 89,8 cmol(+) kg-1, unsur hara K-dd, Ca-dd, Mg-dd, Nadd yang lebih tinggi dibandingkan non zeoponik. Namun hasil analisis tanaman media zeoponik mengandung unsur hara mikro yang rendah. Hasil parameter pertumbuhan pada zeoponik lebih tinggi dibandingkan non zeoponik. Bobot basah sawi, tomat dan terong pada media zeoponik lebih tinggi berturut-turut yaitu 86,54g, 89,27 g, 80,82 g, sementara bobot basah pada media non zeoponik berturut-turut 69,61g, 58,42 g, 44,42 g., The weakness of the current plant growing media (PGM) is the increase in the value of EC when fertilizer is added, so a material that has a high CEC is needed to overcome it. Zeoponic is PGM made from zeolite as the base material mixed with cocopeat and compost. Zeoponics has a high CEC value which can maintain low EC so that plants can grow well which can keep EC low. This study aims to study the chemical characteristics of zeoponic and non-zeoponik PGM, and their effects on the growth of brassica, tomato, and eggplant plants. Single factor completely randomized design (CRD) was used to see the effect of PGM type on plant growth parameters including height, number, leaf length and width, stem diameter, fresh weights and dry weight at 4WAP for brassica and 5WAP for tomato and eggplant. The PGM used were zeoponic mixture of zeolite, cocopeat, and compost (2:1:1) and non-zeoponic mixture of fertile soil and mature organic fertilizer (2:1) as comparison. Analysis of PGM chemical properties was carried out before and after planting. Analysis of macro and micronutrients was carried out on the three plants. The results showed that zeoponic had the advantage of a neutral initial pH of 6,7 and a final pH of 6,8 – 7,0. The appropriate EC value for plant growth of 1,505 mS cm-1 while non-zeoponic had a low EC of 0,187 mS cm-1. Zeoponic contains high CEC of 88,1 – 89,8 cmol(+) kg-1, macronutrients and higher
Keyword: electrical conductivity, macronutrients, micronutrients, zeolite

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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