Judul: Effects of Urea Fertilizer Dosage and Varieties on Growth and Yield of Maize (Zea mays L.)
Abstrak: Jagung adalah komoditas penting di Indonesia yang permintaannya terus meningkat sehingga produktivitasnya perlu ditingkatkan dengan penggunaan benih bermutu dan pemupukan berimbang. Penelitian bertujuan mengetahui pengaruh dosis pupuk Urea dan varietas terhadap pertumbuhan dan produksi jagung. Penelitian dilaksanakan menggunakan rancangan petak terbagi dalam rancangan kelompok lengkap teracak. Perlakuan terdiri dari 2 faktor yaitu varietas dan dosis pupuk Urea. Varietas sebagai petak utama terdiri dari varietas Bisma dan Pioneer 27. Dosis pupuk Urea sebagai anak petak terdiri dari dosis 0, 150, 300, 450, dan 600 kg ha-1. Penelitian menunjukkan dosis pupuk Urea berpengaruh nyata terhadap pertumbuhan dan produksi jagung. Peningkatan dosis pupuk Urea sampai 600 kg ha-1 secara linear nyata meningkatkan bobot kering biomassa, bobot tongkol berkelobot, bobot tongkol, diameter tongkol, bobot biji per tongkol, dan produktivitas. Tinggi tanaman, jumlah daun, dan panjang tongkol menunjukkan respon kuadratik terhadap dosis pupuk Urea dengan rata-rata dosis optimum adalah 417,30 kg ha-1. Terdapat korelasi positif nyata antara peubah tinggi tanaman, jumlah daun, panjang tongkol, dan produktivitas sehingga aplikasi pupuk Urea dengan dosis 450 kg ha-1 adalah yang paling mendekati optimum dan dapat direkomendasikan untuk kedua varietas. Aplikasi pupuk Urea dengan dosis 600 kg ha-1 atau lebih dapat dimanfaatkan untuk produksi jagung untuk pakan ternak., Maize is an important commodity in Indonesia whose demand continues to increase so that its productivity needs to be increased by using quality seeds and balanced fertilization. This study investigates the effect of Urea fertilizer dosage and varieties on the growth and production of maize. The experiment used a split-plot design in a completely randomized group design. The treatment consisted of 2 factors, variety and dose of Urea fertilizer. Varieties as the main plot consisted of Bisma and Pioneer 27. The doses of Urea fertilizer as sub-plots consisted of doses of 0, 150, 300, 450, and 600 kg ha-1. The results showed that the dose of Urea fertilizer had a significant effect on the growth and yield of maize. Increasing the dose of Urea fertilizer up to 600 kg ha-1 linearly significantly increased biomass dry matter, ear weight with husk, ear weight, ear diameter, seed weight per ear, and yield. Plant height, number of leaves, and ear length showed a quadratic response to the dose of Urea fertilizer with an average optimum dose of 417,30 kg ha-1. There is a significant positive correlation between the variables of plant height, number of leaves, ear length, and yield so that the application of Urea fertilizer at a dose of 450 kg ha-1 is the closest to the optimum and could be recommended for both varieties. Urea fertilizer application with a dose of 600 kg ha-1 or more can be used for maize production for animal feed.
Keyword: Bisma, dosis optimum, pakan ternak, Pioneer 27, produksi, animal feed, optimum dose, yield

Judul: The Effect of N Doses Fertilizer and Varieties on Corn Growth and Production in Saturated Soil Culture in Rice Fields
Abstrak: Jagung (Zea mays L.) merupakan komoditas pangan kedua setelah beras yang berperan sebagai sumber karbohidrat. Peningkatan konsumsi jagung perlu diseimbangi dengan peningkatan produktivitas. Penelitian bertujuan mengetahui pengaruh dosis pupuk N dan varietas terhadap pertumbuhan dan produksi jagung pada budidaya jenuh air di lahan sawah. Penelitian menggunakan rancangan percobaan RKLT dengan dua faktor yaitu varietas dan dosis pupuk N. Faktor varietas terdiri atas dua taraf yaitu jagung Sukmaraga dan Pioneer 27. Faktor dosis pupuk N terdiri atas 0 kg N ha-1, 90 kg N ha-1, 135 kg N ha-1, dan 180 kg N ha-1. Hasil penelitian menunjukkan bahwa faktor varietas menunjukkan hasil yang berbeda di awal pertumbuhan yaitu pada karakter tinggi tanaman, diameter batang, dan jumlah daun, serta bobot basah akar. Selain itu terdapat perbedaan pada komponen hasil yaitu pada karakter diameter tongkol, jumlah baris biji per tongkol, dan bobot 100 biji. Dosis N 180 kg N ha-1 memberikan hasil terbaik untuk semua karakter pertumbuhan dan produksi namun tidak berbeda nyata dengan dosis N 135 kg N ha-1. Tidak terjadi interaksi antara faktor varietas dan dosis N., Corn (Zea mays L.) is the second food commodity after rice which acts as a carbohydrate source. Increased consumption of corn needs to be balanced with productivity. This study aims to determine the effect of N fertilizer dosage and varieties on the growth and production of maize in saturated soil culture in paddy fields. This study used an Randomized Complete Block design (RCBD) with two factors, namely the variety and dose of N fertilizer. Variety factors consisted of two levels, namely Sukmaraga and Pioneer 27. The dosage factor for N fertilizer consisted of 0 kg N ha-1 , 90 kg N ha-1, 135 kg N ha-1, and 180 kg N ha-1. The results of this study indicated that the variety factor showed different results at the character of plant height, stem diameter, number of leaves, and root wet weight,the ear diameter, number of seed rows per ear, and the weight of 100 seeds. The N dose of 180 kg N ha-1 gave the best results for all growth and production characters but was not significantly different from the N dose of 135 kg N ha-1. There was no interaction between the variety factor and the N dose.
Keyword: Nitrogen dose, Pioneer 27, Saturated soil culture, Sukmaraga

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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