Judul: Pengaruh Dosis Pupuk NPK 15-10-12 dan Potensi Bacillus subtilis terhadap Pertumbuhan dan Produksi Hasil Tanaman Ubi Jalar.
Abstrak: Kebutuhan terhadap ubi jalar yang terus meningkat tidak sebanding dengan produksi tanaman yang cenderung fluktuatif. Penggunaan pupuk majemuk bersubsidi menjadi salah satu alternatif untuk meningkatkan produksi dan efisiensi kegiatan budidaya, akan tetapi belum ada pupuk yang disubsidi untuk tanaman ubi jalar. Perlu diketahui apakah substitusi pupuk subsidi lain seperti NPK 15-10-12 yang diperuntukkan pada tanaman jagung juga mampu meningkatkan produksi tanaman ubi jalar. Penelitian dilaksanakan bulan November 2023 hingga Januari 2024 di Kebun Percobaan Sawah Baru. Rancangan percobaan yang digunakan RKLT dua faktor yaitu varietas (Antin3, Beta1) dan dosis. Dosis pemupukan terdiri dari lima taraf yaitu pupuk NPK 15-10-12 0, 100, 200, 300 kg ha-1 , dan Bacillus subtilis 2,5 ml L -1 dengan volume semprot 500 L ha-1 . Hasil penelitian menunjukkan varietas Antin 3+Bacillus subtilis menghasilkan jumlah umbi layak pasar tertinggi yaitu 50% dan bobot umbi per petak tertinggi yaitu 22,13 kg. Kombinasi varietas Antin 3+200 kg ha-1 NPK 15-10-12 menghasilkan umbi dengan kemanisan tertinggi yaitu 11,16 °brix. Dosis rekomendasi NPK 15-10-12 pada varietas Antin 3 yaitu 179,08 kg ha-1 , dan 131,86 kg ha-1 pada varietas Beta 1., The increasing demand for sweet potato is not proportional to the fluctuating crop production. The use of subsidized compound fertilizers is one alternative to increase production and efficiency of cultivation activities, but there is no subsidized fertilizer for sweet potato crops. It is necessary to know whether the substitution of other subsidized fertilizers such as NPK 15-10-12 which is intended for corn crops is also able to increase sweet potato crop production. The research was conducted from November 2023 to January 2024 at Sawah Baru Experimental Farm. The experimental design used RKLT two factors, namely variety (Antin3, Beta1) and dose. The fertilization dose consisted of five levels, namely NPK 15-10-12 fertilizer 0, 100, 200, 300 kg ha-1, and Bacillus subtilis 2,5 ml l-1 with a spray volume of 500 l ha-1 . The results showed that the Antin 3 variety + Bacillus subtilis produced the highest number of marketable tubers at 50% and the highest tuber weight per plot at 22,13 kg. The combination of Antin 3 variety + 200 kg ha-1 NPK 15-10-12 produced tubers with the highest sweetness of 11,16 °brix. Recommended dose of NPK 15-10-12 on Antin 3 variety is 179,08 kg ha-1 , and 131,86 kg ha-1 on Beta 1 variety.
Keyword: Antin 3, Beta 1, productivity

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: 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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