Judul: The Growth and Prodution of Sweet Potatoes (Ipomoea batatas L.) Ase Kapas Clones With Different Doses of Phosphorous Fertilizer.
Abstrak: Ubi jalar merupakan sumber karbohidrat non beras yang mampu meningkatkan ketersediaan pangan dan diversifikasi pangan. Pemupukan salah satu faktor penting dalam budidaya tanaman ubi jalar. Penelitian ini bertujuan untuk menguji beberapa dosis fosfor optimal terhadap pertumbuhan dan produksi ubi jalar varietas ase Kapas. Percobaan penelitian ini dilakukan di Kebun Perobaan Cikabayan IPB dan Laboratorium Pasca Panen dari bulan Januari 2020 hingga Juli 2020. Percobaan penelitian disusun dalam Rancangan Kelompok Lengkap Teracak (RKLT) faktor tunggal dengan lima taraf percobaan yaitu 0 kg ha-1 SP36, 50 kg ha-1 SP36, 100 kg ha-1 SP36, 150 kg ha-1 SP36, 200 kg ha-1 SP36 dari dosis pupuk rekomendasi (100 kg ha-1 SP36). Terdapat tiga ulangan dengan lima perlakuan sehingga ada 15 percobaan. Ubi jalar Ase Kapas menunjukkan respon kuadratik terhadap peningkatan dosis pupuk P untuk peubah pertumbuhan tajuk, jumlah daun aktif dan jumlah cabang dengan nilai maksimum pada rata-rata dosis pupuk 143,6 kg SP36 ha-1. Produksi umbi tidak menunjukkan respon yang nyata terhadap peningkatan dosis pupuk SP36. Pada kondisi tanah kebun percobaan dengan status P tersedia yang rendah (8,3 ppm atau setara 16,6 kg ha-1 pada kedalaman 20 cm) maka secara praktis pupuk SP36 dapat diberikan dengan dosis 150 kg SP36 ha-1 atau 150% dosis pupuk rekomendasi., Sweet potato is a source of non-rice carbohydrates that can increase food security and diversity food. Fertilization an important factor in the cultivation of the sweet potato plant. The research aimed to determine the optimum fertilizer doses of the fertilizer for the growth and production of seet potato Ase Kapas clone. The experiment was performed at the field experiment Cikabayan IPB and post-harvest laboratory from January 2020 to July 2020. The experiment was arranged in a Randomized Complete Design Group (RCBD) single with single factor of phosphor fertilier dose is 0, 50, 100, 150, 200 kg ha-1 SP36 (100 kg ha-1 SP36 is a reference dose). There were three repliations with five treatments that led to 15 trials. Ase Kapas sweet potato showed a quadratic response to an increase in the dose of phosphorus fertilizer for crown growth variables, the number of active leaves and the number of branches with maximum values in the range average 143,6 kg SP36 ha-1. Tuber production did not show a significant response to increasing the dose of SP36 fertilizer. In the soil conditions with low available phosphorus status (8,3 ppm or equivalent to 16,7 kg ha-1 at a deep of 20 cm), SP36 fertilizer can be given at a dose of 150 kg SP36 ha-1 or 150% of the reference dose.
Keyword: Phosphorus fertilizer, regression analysis, sweet potato

Judul: Effect of NPK 17-6-25 Fertilizer Dosage and  the Potential of Bacillus subtilis on Growth and Production of Sweet Potato (Ipomoea batatas L.)
Abstrak: Peningkatan kebutuhan ubi jalar tidak sebanding dengan produktivitas ubi jalar. Inovasi pemupukan majemuk yang secara khusus untuk produksi ubi jalar diperlukan dalam mendukung efisiensi budidaya. Pupuk NPK 17-6-25 sudah terbukti efektif terhadap pertumbuhan dan produksi ubi kayu, hal ini memberi peluang penggunaannya dalam pemupukan ubi jalar. Penelitian dilaksanakan di Kebun Percobaan Sawah Baru, Departemen Agronomi dan Hortikultura dan Laboratorium Pasca Panen, Institut Pertanian Bogor dari bulan Oktober 2023 hingga Februari 2024. Penelitian menggunakan rancangan kelompok lengkap teracak dua faktor yaitu varietas ubi jalar dengan 2 taraf Antin 3 dan Beta 1, serta dosis pemupukan NPK 17-6-25 0 kgha-1, 100 kgha-1, 200 kgha-1, 300 kg ha-1 dan 1 taraf pemupukan Bacillus subtilis 2,5 ml l-1. Hasil penelitian menunjukkan bahwa pertumbuhan vegetatif varietas Beta 1 lebih baik dari Antin 3. Perlakuan dosis pupuk NPK 17-6-25 100 – 300 kg ha-1 memberikan peningkatan hasil produksi dengan bobot umbi per petak sebanyak 21,54–24,81 kg dan bobot total umbi sampel sebanyak 6,39 kg. Kedua varietas ubi jalar memberikan respon yang berbeda terhadap perlakuan Bacillus subtilis. Dosis optimum pemupukan NPK 17-6-25 pada varietas Antin 3 sebanyak 235,35 kgha-1, dan untuk varietas Beta 1 sebanyak 176,75 kgha-1., The increasing demand for sweet potatoes is not proportional to their productivity. Innovation in compound fertilization specifically for sweet potato production are needed to support cultivation efficiency. NPK 17-6-25 fertilizer has proven effective for the growth and production of cassava, offering potentialfor its use in sweet potato fertilization. The research was conducted at the Sawah Baru Experimental Farm, Departement of Agronomy and Horticulture and Post–Harvest Laboratory, Bogor Agricultural University, from October 2023 to February 2024. The study used a two-factor randomized complete group design with sweet potato varieties (Antin 3 and Beta 1), and NPK 17-6-25 fertilizer doses of 0 kg ha-1, 100 kg ha-1, 200 kg ha-1, 300 kg ha-1, and one level Bacillus subtilis treatment at 2,5 ml l-1. The results showed that the vegetative growth of Beta 1 was better than that of Antin 3. Treatment with NPK fertilizer 17-6-25 doses of 100 300 kg ha-1 increased production yield, with tuber weights per plot ranging from 21,54 to 24,81 kg and total sample tuber weight of 6,39 kg. The two sweet potato varieties responded differently to Bacillus subtilis treatment. The optimum dose of NPK 17-6-25 fertilizer for the Antin 3 variety was 235,35 kg ha-1 and for the Beta 1 variety, it was 176,75 kg ha-1.
Keyword: produktivitas, antin 3, beta 1, umbi layak pasar

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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