Judul: Dampak Penggunaan ZA secara Terus Menerus terhadap Status Hara Mikro Tanah pada Beberapa Kebun di Perkebunan Tebu PG Colomadu PTP XV-XVI Surakarta
Abstrak: Penelitian ini bertujuan untuk mengatasi dampak penggunaan ZA (Ammonium Sulfat) secara terus menerus terhadap status hara mikro tanah (Cu, Zn, Mn, Fe) serta hubungannya dengan produksi dan rendeman tebu pada beberapa kebun di perkebunan tebu PG Colomadu, PTP XV-XVI Surakarta, Jawa Tengah.
Keyword: 

Judul: Pengaruh Pemberian Takaran Pupuk Amonium Sulfat terhadap Pertumbuhan, Produksi, Kadar dan Serapan Hara Tanaman Jagung (Zea mays L.) Pada Latosol Dramaga, Bogor
Abstrak: Maize (Zea mays L.) is one of food commodities and alternative forage that has been cultivated in Indonesia for a long time. The potential for post-harvest processing and food diversification encourage further development of maize cultivation. The aim of this study was to determine the effective doses of nitrogen fertilizer (ZA) application for growth, production, plant nutrients concentration and nutrient uptake of maize. The study was conducted in an experiment field using a Randomized Block Design, with eight treatments that were unfertilizer plot (Control), ZA-Standard, Urea-Standard and ZA-Tests in different doses of awarding (0.25 ZA, 0.50 ZA, 1.00 ZA, 1.50 ZA, 2.00 ZA). Each treatment was performed in three replications. Results showed that the highest growth of plant, maize production, N plant concentration and N uptake were achieved in treatment of 1.00 ZA, although it was not statistically different compared with the other treatments, except Control (unfertilizer plot) and 0.25 ZA treatment. The highest percentage of RAE (Relative Agronomic Effectiveness) was achieved by 1.00 ZA treatment, and its RAE value was increased up to 35.03% than ZA Standard.
Keyword: Bogor Agricultural University (IPB), production, plant nutrients concetration, maize, growth, ammonium sulfate

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: