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: Response of Fertilizing B and NPK to the growth of sweet  corn plants (Zea mays L. Saccharata) on Dramaga Inceptisols
Abstrak: Jagung manis (Zea mays L. Saccharata) adalah salah satu tanaman pangan dan bahan baku industri di Indonesia dan dunia. Peningkatan produktivitas jagung manis dapat dilakukan melalui optimasi pemupukan nitrogen (N), fosfor (P), kalium (K) dan boron (B) merupakan hara makro dan mikro esensial yang dibutuhkan tanaman jagung untuk dapat tumbuh dan berkembang serta berproduksi secara optimal. Penelitian ini bertujuan untuk mengetahui kandungan B dan NPK dalam tanah dan tanaman serta pertumbuhan dan perkembangan jagung manis sebagai respon dari kombinasi pemberian pupuk mikro B dan NPK pada Inceptisol Dramaga. Penelitian menggunakan Rancangan Acak Kelompok (RAK) dengan delapan perlakuan (B0S0, B0S1, B1S1, B2S1, B3S1, B1S2, B2S2, B3S2) yang terdiri dari empat taraf B (0, 9, 18, 27 kg/ha) dan tiga taraf NPK (0%, 75% dan 100% std). Perlakuan diulang kedalam empat kelompok menghasilkan 32 petak percobaan. Kombinasi pemberian pupuk B dan NPK signifikan meningkatkan B tersedia dalam tanah. Selain itu, pemberian pupuk B dan NPK meningkatka panjang daun, dan kadar B dalam tanaman serta mempercepat umur berbunga betina (silking). Pemberian 9-18 kg/ha B dan 75% NPK memiliki pengaruh positif yang relatif konsisten pada semua parameter agronomis yang diteliti. Perlu adanya penelitian lanjutan untuk melihat pengaruh pemberian pupuk B dan NPK terhadap produksi jagung manis pada tanah dengan kesuburan yang berbeda-beda, serta kombinasi waktu dan cara pemupukan B., Sweet corn (Zea mays L. Saccharata) is one of the staple crops and raw materials for the industry in Indonesia and globally. Increasing the productivity of sweet corn can be achieved through the optimization of nitrogen (N), phosphorus (P), potassium (K), and boron (B) fertilization, which are essential macro and micronutrients required for the optimal growth, development, and production of corn plants. This research aims to determine the content of B and NPK in soil and plants, as well as the growth and development of sweet corn in response to the combination of B and NPK micro-fertilizer application in Inceptisol Dramaga. The study utilized a Randomized Complete Block Design (RCBD) with eight treatments (B0S0, B0S1, B1S1, B2S1, B3S1, B1S2, B2S2, B3S2) consisting of four levels of B (0, 9, 18, 27 kg/ha) and three levels of NPK (0%, 75%, and 100% standard). The treatments were replicated into four blocks, resulting in 32 experimental plots. The combination of B and NPK fertilizer application significantly increased the available B in the soil. Additionally, B and NPK fertilization enhanced leaf length, and B content in the plants, as well as accelerate the female flowering age (silking). The application of 9-18 kg/ha B and 75% NPK showed a relatively consistent positive influence on all agronomic parameters studied. Further research is needed to examine the impact of B and NPK fertilizer application on sweet corn production in soils with varying fertility and explore the timing and methods of B fertilization
Keyword: Availability, boron, NPK, soil parameters, sweet corn

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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