Judul: Population of Soil Organisms in Sukamantri Andisol Planted with Sweet Corn (Zea mays saccharata Sturt) in Sukamantri Village
Abstrak: Keberadaan organisme tanah sangat penting bagi keseimbangan suatu ekosistem tanah yang dipengaruhi oleh faktor-faktor lingkungan seperti kadar air, pH tanah, suhu tanah, bahan organik, dan kandungan unsur hara. Penelitian ini bertujuan mempelajari kelimpahan dan keanekaragaman organisme tanah pada tanah Andisol yang ditanami Jagung manis (Zea mays saccharata Sturt) di kebun percobaan IPB University, Kecamatan Sukamantri, Kabupaten Bogor. Pengambilan contoh tanah untuk pengumpulan mikrob dan fauna tanah dilakukan menggunakan metode simple random sampling. Contoh tanah diambil pada plot percobaan dengan perlakuan pemupukan : 1. Tanah kontrol (P0), 2. Tanah + pupuk kandang sapi 6 ton/ha (P1), 3. Tanah + Pupuk NK 200 kg/ha (P2) dan 4. Tanah + Pupuk NK 400 kg/ha (P3). Pengambilan sampel dilakukan dua kali, yaitu pada umur jagung 42 hari setelah tanam (HST) dan saat panen (90 HST). Fauna tanah diekstrak dengan metode Berlesse Funnel Extractor. Isolasi dan perhitungan total mikrob dan fungi dilakukan menggunakan metode Total Plate Count. Kelimpahan fauna tanah tertinggi ditemukan pada plot percobaan yang ditambah pupuk NK 400 kg/ha baik pada 42 HST (1445 individu/m2 ) dan 90 HST (987 induvidu/m2). Populasi tertinggi mikrob dan fungi tanah diperoleh pada plot yang ditambah dengan pupuk kandang baik pada 42 HST maupun 90 HST., The existence of soil organisms is very important for the balance of a soil ecosystem which is influenced by environmental factors such as water content, soil pH, soil temperature, organic matter and nutrient content. This research aims to study the abundance and diversity of soil organisms in Andisol planted with sweet corn (Zea mays saccharata Sturt) at the IPB University Experimental Site, Sukamantri District, Bogor Regency. Soil sampling for collecting soil microbes and fauna was carried out using the simple random sampling method. Soil samples were taken from experimental plots with fertilizer treatments: 1. Control (P0), 2. Soil + cow manure 6 tons/ha (P1), 3. Soil + NK fertilizer 200 kg/ha (P2) and 4. Soil + NK fertilizer 400 kg/ha (P3). Sampling was carried out twice, namely when the corn was 42 days after planting (DAP) and at harvest (90 DAP). Soil fauna was extracted using the Berlesse Funnel Extractor method. Total microbes and fungi were analysed using Total Plate Counting method. The highest abundance of soil fauna was found in experimental plots where 400 kg/ha of NK fertilizer was added at both 42 DAP (1445 individuals/m2) and 90 DAP (987 individuals/m2). The highest populations of soil microbes and fungi were obtained in plots supplemented with manure at both 42 DAP and 90 DAP.
Keyword: abundance of soil fauna, fungi, manure, microbes, NK fertilizer

Judul: Pengaruh Pupuk Organik dan NPK terhadap Serapan Hara dan Hasil Jagung Manis di Latosol Dramaga.
Abstrak: Sweet corn cultivation carried out by farmers around Bogor commonly only use inorganic fertilizers without incorporating the corn stalks into the soil and used as animal feed. Cultivation as above continously can lead to decreased of soil organic matter. This trial was conducted to test the effectiveness of organic manure and NPK fertilizer on the growth and yield of sweet corn. This trial was conducted in IPB experimental station at Cikabayan from May 2014 until November 2014. Factorial randomized block design was used in this trial with two factors. The first factor was the organic manure with 3 levels of dosages, namely: O0 = 0 t/ha, O1 = 2.5 t/ha (6:25 kg/plot) and O2 = 5 t/ha (12.5 kg/plot). The second factor was the NPK fertilizer with 4 levels namely: P0 = 0%, P1 = 50%, P2 = 75% and P3 = 100% standard dosage of NPK. Standard dosage of NPK fertilizer consisting of urea 250 kg/ha, SP-36 150 kg/ha and KCl 200 kg/ha. Variables measured were plant height, weight of cob and dry biomass, nutrient uptake and Relative Agronomic Effectiveness (RAE). The results showed that treatment of NPK fertilizer increased crop height while main effect of organic manure did not significantly incrace. Treatment with a combination of organic manure and NPK fertilizer increased the weight of cob and dry biomass. NPK fertilizers influenced the uptake of N, K and dry biomass, but not significanly on the uptake of P. Acording to relative agronomic effectiveness showed that the application of organic manure could reduce the NPK fertilizer.
Keyword: Nutrient uptake, yield, organic manure

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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