Judul: Growth and Production of Sugarcane (Saccharum officinarum L.) First Ratoon in Residual Filter Cake and Inorganic Fertilizer.
Abstrak: Intensifikasi tebu keprasan lahan kering merupakan salah satu cara dalam rangka meningkatkan produksi gula nasional. Penelitian dilakukan bulan Agustus 2019 - Juli 2020 pada tebu keprasan pertama di lahan percobaan PT Kebun Tebu Mas, Lamongan, Jawa Timur dengan rancangan split split plot. Perlakuan terdiri atas 3 faktor yaitu varietas (PS 881 dan PS 862) sebagai petak utama, residual kompos blotong (taraf residual pupuk blotong 0, 5, dan 10 ton ha-1) sebagai anak petak, dan residual pupuk anorganik (residual pupuk 25%, 50%, 75%, dan 100% dosis rekomendasi) sebagai anak-anak petak. Hasil penelitian menunjukkan bahwa pertumbuhan varietas PS 862 lebih baik daripada PS 881 pada keragaan tinggi tanaman, panjang ruas, diameter, panjang batang, dan jumlah batang. Residual kompos blotong memiliki pengaruh nyata lebih baik pada taraf 10 ton ha-1 pada panjang ruas. Residual pupuk anorganik taraf 75% memiliki respon yang lebih baik pada peubah jumlah daun, jumlah tunas, jumlah batang dan diameter. Varietas PS 862 dengan 5 ton ha-1 residual kompos blotong menghasilkan bobot batang terbaik sebesar 0,48 kg m-1. Varietas PS 862 dengan 75% residual pupuk anorganik menghasilkan hasil tebu sebesar 78,52 ton ha-1 dan tidak berbeda nyata dengan residual 100% pupuk anorganik., Intensification of upland sugarcane is one way to increase national sugar production. The research was conducted in August 2019-July 2020 on the experimental field of PT Kebun Tebu Mas, Lamongan on the first ratooncane with a split-split plot design. The treatment consisted of three factors, variety (PS 881 and PS 862 as main plots), residual filter cake (0, 5, and 10 tons ha-1) as subplots, and inorganic fertilizer residues (25, 50, 75, and 100% recommended doses) as subsubplots. The results showed that growth and yield of PS 862 was better than PS 881 in the performance of plant height, internode length, diameter, stem length, and number of stems. The residue of blotong compost had a significantly better effect at the level of 10 tons ha-1 on internode length. Residual inorganic fertilizer level 75% had a better response to the variables of number of leaves, number of shoots, number of stems and diameter. The PS 862 with 5 tons ha-1 residual blotong compost produced the best stem weight of 0.48 kg m-1. The PS 862 variety with 75% residual inorganic fertilizer produced sugarcane yields of 78.52 tons ha-1 and was not significantly different from the residual 100% inorganic fertilizer.
Keyword: intensification, PS 881, PS 862, sugar, upland

Judul: Management of Sugarcane (Saccharum  officinarum L.) at Kebun Tebu Mas, Sugar Factory in Lamongan with Special  Aspect of Productivity in Each Plant Category
Abstrak: Gula merupakan salah satu komoditas terpenting nomor dua setelah beras yang kebutuhannya masih sangat tinggi di industri maupun rumah tangga. Pengelolaan tebu dilakukan untuk meningkatkan hasil produktivitas di tiap kategori tanaman. Tebu yang dikepras secara berulang dapat menyebabkan turunnya produktivitas. Tujuan magang adalah untuk membandingkan produktivitas tebu setiap kategori tanaman tahun giling 2021 dengan produktivitas tebu setiap kategori tanaman tahun giling 2020. Kegiatan magang dilaksanakan pada 25 Januari hingga 12 Mei 2021 di PG Kebun Tebu Mas, Lamongan, Jawa Timur. Hasil pengamatan menunjukan produktivitas tanaman tebu pada varietas Cening dan Bululawang menunjukan peningkatan produktivitas pada tahun giling 2021, kecuali varietas Cening ratoon cane (RC) atau tanaman keprasan (RC) III yang mengalami penurunan produktivitas. Produktivitas tertinggi pada varietas Cening terdapat pada kategori tanaman RC II, sedangkan pada varietas Bululawang pada kategori tanaman plant cane (PC) atau tanaman pertama. Analisis usaha tani menunjukan kategori tanaman RC pada kedua varietas memiliki keuntungan lebih tinggi daripada kategori tanaman PC., Sugar is one of the most important commodities after rice whose need is still very high in industry and households. Sugarcane management is carried out to increase productivity in each plant category. Sugarcane that is ratooned repeatedly can cause a decrease in productivity. The purpose of this internship is to compare the productivity of each plant category in the 2021 milled year with sugarcane productivity in each category for the 2020 milled year. The internship was held from January 25th until May 12th, 2021 at Kebun Tebu Mas’ Sugarcane, Lamongan, East Java. The results showed that the productivity of sugarcane in the Cening and Bululawang varieties showed an increase in productivity in the 2021 milling year, except for the variety of Cening’s RC III, which experienced a decrease in productivity. The highest productivity in the Cening was in the ratoon cane (RC) II plant category, while in the Bululawang was in the first plant or plant cane (PC) category. Farming analysis showed that the RC plant categories in both varieties had the highest profit compared to the PC plant category.
Keyword: gula, produktivitas, tanaman pertama, tanaman keprasan

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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