Judul: Karakterisasi Dan Analisis Kandungan Nitrat Tanaman Pakis Sayur (Pleocnemia irregularis (C. Presl) Holttum) Di Kecamatan Dramaga, Bogor
Abstrak: The aimed of the study was to characterizing and learning the differences of Pleocnemia irregularis character in three different places at Dramaga and to analize nitrate content of edible part from Pleocnemia irregularis. The research was conducted from October 2009 to March 2010 at Arboretum of Forestry Faculty, Bogor Agricultural University (Arboretum Fahutan) as the first place and Dramaga Research Forest of Bogor Research Centre and Forest Concervacy for the second and third places (CIFOR 1 and CIFOR 2). The result showed that there are no differences of qualitative character among those three location. Based on quantitave character, P. irregularis at CIFOR 2 is the smallest than the other location. The nitrate content of edible part P. irregularis at all of tested locations are under the safe limit of Acceptable Daily Intake for human with 60 kg of body weight and 100 g per day consumption. The harvest intensity of Arboretum Fahutan are the fastest (4.13 week/ harvest) without differences in percentage of edible part among locations.
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Judul: Spatial Distribution of Soil Nutrients in Sawah Baru Agriculture Fields, Dramaga District, Bogor Regency
Abstrak: Tanaman padi merupakan komoditas pangan utama yang dikonsumsi masyarakat Indonesia. Kabupaten Bogor salah satu wilayah yang berkontribusi signifikan dalam memenuhi kebutuhan komoditas padi di Jawa Barat dan sekitarnya. Akan tetapi, masih terdapat permasalahan pada penurunan produksi, produktivitas dan luas panen lahan padi sawah. Pemanfaatan metode interpolasi Ordinary Kriging bagi lahan sawah di Indonesia masih sangat minim, terutama informasi status hara pada lahan pertanian di Kabupaten Bogor. Penelitian ini bertujuan untuk menganalisis, memetakan, dan membandingkan pola spasial parameter kesuburan tanah (pH H2O, C-organik, dan status hara tanah) pada tanaman padi menggunakan metode Kriging di Lahan Sawah Baru Dramaga, Kabupaten Bogor. Hasil penelitian menunjukkan keragaman semivariogram dari setiap parameter kesuburan tanah (pH H2O, C-organik, N-total, P-tersedia, P-total, K-total, yang dapat ditukar (Ca-dd, Mg-dd, K-dd, Na), KTK dan KB) yang dikuantifikasi dari nugget effect, sill, dan range dalam semivariogram. Distribusi spasial beberapa parameter kesuburan tanah di wilayah penelitian bervariasi dengan rentang dari sangat rendah sampai dengan sangat tinggi dengan akurasi berbeda. Pemetaan dengan metode interpolasi Ordinary Kriging melalui semivariogram spherical juga menunjukkan tingkat akurasi berbeda. Parameter pH H2O, K-total, Ca-dd, dan Mg-dd mempunyai akurasi yang lebih kuat serta parameter P-total dan Kdd mempunyai akurasi yang moderat dibandingkan parameter lain. Sedangkan, parameter C-organik, P-tersedia, N-total, Na-dd, KTK, dan KB mempunyai akurasi yang lebih lemah menunjukkan parameter tersebut kurang akurat dalam menggambarkan kondisi aktual wilayah penelitian., Rice is a main food commodity consumed by Indonesians. Kabupaten Bogor is one of the regions that significantly contributes to West Java’s demand. However, problems in production decrease, productivity, and total harvested paddy field have widely been acknowledged, whilst land resource datasets have largely been insufficient. This research assessed ordinary kriging interpolation, which has been limitedly investigated on the retrievals of soil nutrients. This research goal was to analyze, to map, and to compare spatial pattern of soil fertility parameters (pH H2O, soil organic carbon (OC), and soil nutrient status). Experiment was conducted in Sawah Baru agriculture fields, Kecamatan Dramaga, Kabupaten Bogor. Results showed a variety of semivariogram, observed from soil fertility parameters (i.e., pH H2O, soil organic carbon (OC), Total-N, P-Available, Total-P, Total-K, Exchangeable Ca, Mg, K, Na, cation exchange capacity (CEC), and base saturation), with respect of nugget effects, sills, and ranges in respective semivariograms. Spatial distribution of soil fertility parameters broadly varied with divergent accuracies. Modeling using spherical-type semivariogram also indicated unassociated levels of accuracy. pH H2O, Total-K, Exchangeable Ca, and Exchangeable Mg were parameters with strong accuracy levels, while Total-P and Exchangeable K displayed moderate accuracy compared to other parameters. Meanwhile, soil organic carbon (OC), P-Available, Exchangeable Na, CEC and base saturation indicated a lower accuracy, suggesting that those parameters warrant an in-depth analysis in the future.
Keyword: Ordinary Kriging, kesuburan, semivariogram, fertility

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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