Judul: Response of Three Varietas Water Spinach (Ipomea reptans  Poir) to Increased NPK Fertilization
Abstrak: Kangkung darat (Ipomea reptans Poir) merupakan komoditas hortikultura yang banyak dibudidayakan dan digemari karena waktu panennya yang cepat dan mudah dibudidayakan. Namun seiring berjalannya waktu produksi tanaman kangkung terus menurun setiap tahunnya. Penggunaan pupuk majemuk dan pemilihan varitas unggul merupakan salah satu solusi dan alternatif untuk meningkatkan produksi dan efisiensi budidaya. Penelitian ini bertujuan mendapatkan informasi interaksi dan respon tiga varietas kangkung terhadap pemberian dosis pupuk NPK yang berbeda pada pertumbuhan dan hasil. Penelitian ini dilakukan pada bulan April hingga Mei 2024 di Desa Cikura, Kabupaten Banjarnegara, Jawa Tengah. Penelitian ini menggunakan rancangan kelompok lengkap teracak dengan dua faktor dosis dan varietas yang terdiri atas tiga ulangan. Faktor pertama yaitu dosis pemupukan dengan 4 taraf dosis pemupukan yaitu 0 NPK, 0,5 g tan-1 NPK, 1 g tan-1 NPK, dan 1,5 g tan-1. Faktor kedua yaitu varietas menggunakan 3 varietas komersil yaitu Bangkok LP-1, Rajawali, dan Serimpi. Hasil penelitian menunjukkan bahwa dosis pupuk 1,5 g tan-1 mampu meningkatkan tinggi tanaman, jumlah daun dan berat segar tanaman. Varietas Bangkok LP-1 dapat meningkatkan pertumbuhan dan hasil tanaman kangkung. Hasil penelitian menunjukan tidak terdapat interaksi yang nyata antara dosis pupuk NPK dan tiga varietas kangkung terhadap pertumbuhan dan hasil tanaman kangkung, Water spinach (Ipomea reptans Poir) is a horticultural plant widely cultivated and favored due to its quick harvest time and ease of cultivation. Bu, as time goes by, water spinach production continues to decline every year. The use of compound fertilizers and the selection of superior varieties are among the solutions and alternatives to increase production and cultivation efficiency. This study aims to determine the effect of NPK fertilizer dosage on the growth and yield of three varieties of water spinach (Ipomea reptans Poir). The research was conducted from April to May in Cikura Village, Banjarnegara Regency, Central Java. This study used a randomized complete group design with two factors, dose and variety, consisting of three replications. The first factor is the fertilizer dose with 4 levels of fertilizer dose namely 0 NPK, 0.5 g tan-1 NPK, 1 g tan-1 NPK, dan 1.5 g tan-1. The second factor is the variety using 3 commercial varieties, namely Bangkok LP-1, Rajawali, and Serimpi. The research results showed that a fertilizer dose of 1.5 g tan-1 was able to increase plant height, number of leaves and fresh weight of plants. The Bangkok LP-1 variety can increase the growth and yield of kale plants. The results of the research showed that there was no real interaction between the dose of NPK fertilizer and the three varieties of kale on the growth and yield of kale plants.
Keyword: Bangkok LP-1, dosage, interaction

Judul: Optimizing Fertilizer Dosages in Water Spinach Cultivation Using Fertigation Through Drip Irrigation
Abstrak: Peningkatan produktivitas tanaman kangkung varietas Bangkok-LP1 dapat dilakukan dengan cara pemberian dosis pupuk yang optimum berdasarkan analisis tanah secara fertigasi melalui irigasi tetes. Penelitian ini bertujuan untuk mengetahui rekomendasi dosis pupuk yang tepat untuk tanaman kangkung sehingga mencapai produktivitas yang maksimal. Penelitian dilakukan mulai bulan Juli sampai Oktober 2023 di Kebun Percobaan Cikarawang, Institut Pertanian Bogor, yang memiliki jenis tanah inceptisol dengan kandungan C-Organik 1,38%, P-Tersedia 5,5 ppm (sangat rendah), K-Tersedia 33,1 ppm (rendah), dan pH 6,03 (masam). Penelitian ini menggunakan Rancangan Kelompok Lengkap Teracak (RKLT) dengan satu faktor yaitu perlakuan 5 dosis pemupukan 0%X, 50%X, 100%X, 150%X, dan 200%X, dengan X adalah dosis 219 kg N ha-1, 374 kg P2O5 ha-1, 187 kg K2O ha-1 dengan 4 ulangan. Hasil penelitian menunjukkan bahwa aplikasi pemupukan menggunakan fertigasi melalui irigasi tetes sampai 200% rekomendasi Ferads tidak memberikan pengaruh yang nyata pada pertumbuhan dan produksi kangkung varietas Bangkok-LP1. Produktivitas kangkung varietas Bangkok-LP1 mencapai 13,64 ton ha-1 pada penanaman pertama, sedangkan pada penanaman kedua dengan residu pemupukan menghasilkan 12,33 ton ha-1., Increasing the productivity of the Bangkok-LP1 variety of water spinach plants can be done by providing optimum fertilizer rate based on soil analysis using fertigation through drip irrigation. This research aims to determine the recommended fertilizer rate for water spinach plants to achieve maximum yield. The research was conducted from July to October 2023 at the Cikarawang Experimental Station, Bogor Agricultural University, which has an inceptisol soil type with a C-Organic content of 1,38%, P-Available 5,5 ppm (very low), K-Available 33,1 ppm (low), and pH 6,03 (acid). This study used a Randomized Completely Block Design (RCBD) with one factor, with 5 level fertilizer rate of 0%X, 50%X, 100%X, 150%X, and 200%X, where 219 kg N ha-1, 374 kg P2O5 ha-1, 187 kg K2O ha-1 with 4 replications. The results of the research showed that fertilization application using fertigation through drip irrigation up to 200% as recommended by Ferads did not have a significant effect on the growth and yield of the Bangkok-LP1 variety of water spinach. The productivity of the Bangkok-LP1 variety of water spinach reached 13.64 tons ha-1 in the first planting, while in the second planting with fertilizer residue it produced 12.33 tons ha-1.
Keyword: ferads

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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