Judul: Effect of Subsurface Plastic Mulch Application on Growth and Production of Four Soybean Varieties
Abstrak: Kedelai merupakan salah satu komoditas pangan penting yang dapat diolah menjadi tahu, tempe, susu kedelai, dan kecap. Peningkatan produksi kedelai dapat dilakukan dengan perluasan areal tanam dan peningkatan produktivitas. Peningkatan produktivitas dapat dilakukan dengan pemberian air yang cukup bagi tanaman. Penelitian ini bertujuan mendapatkan informasi mengenai pengaruh mulsa plastik bawah tanah terhadap pertumbuhan dan produksi empat varietas kedelai. Penelitian dilakukan di Kebun Percobaan IPB Sawah Baru dari bulan Januari hingga Mei 2021. Percobaan menggunakan rancangan petak terbagi dengan tiga ulangan. Petak utama yaitu mulsa plastik bawah tanah dan tanpa mulsa plastik bawah tanah serta anak petak yaitu kedelai varietas Detam-1, Gepak Kuning, Grobogan, dan Anjasmoro. Hasil penelitian menunjukkan bahwa perlakuan mulsa plastik bawah tanah dapat meningkatkan kelembapan tanah, tinggi tanaman, jumlah daun trifoliate, jumlah cabang, dan indeks luas daun. Gepak Kuning merupakan varietas yang menghasilkan jumlah polong, jumlah polong isi, jumlah biji, jumlah biji per polong, dan produksi riil yang lebih tinggi dibandingkan varietas lainnya. Detam-1 memiliki jumlah polong hampa, persentase polong hampa, bobot basah polong hampa, dan evapotranspirasi yang lebih tinggi dibandingkan varietas lainnya. Anjasmoro dan Gepak Kuning memiliki nilai efisiensi pemakaian air yang lebih tinggi dibandingkan dua varietas lainnya., Soybean is one of important food commodities that can be processed into tofu, tempe, soy milk, and soy sauce. Soybean production can increase by expanding the planting area and increasing productivity. Increased productivity can be done by providing sufficient water for plants. This research aimed to study the effect of subsurface plastic mulch application on growth and production of four soybean varieties. This research was conducted in Teaching Farm Sawah Baru IPB from January to May 2021. This research used split plot design with three replications. The main plot was subsurface plastic mulch, non-subsurface plastic mulch and the sub plot was soybean varieties (Detam-1, Gepak Kuning, Grobogan, and Anjasmoro). The results showed that subsurface plastic mulch increased soil moisture, plant height, number of trifoliate leaves, number of branches, and leaf area index. Gepak Kuning variety has the higher number of pods, number of filled pods, number of seeds, number of seeds per pod, and real production compared to other varieties. Detam-1 has higher number of empty pods, percentage of empty pods, wet weight of empty pods, and evapotranspiration compared to other varieties. Anjasmoro and Gepak Kuning have a higher water use efficiency value than other two varieties.
Keyword: gepak kuning, leaf area index, moisture

Judul: The Effect of Chemical Fertilizer Dosage and Type of Biofertilizer on the Growth and Production of Soybean (Glycine max L.)
Abstrak: Kedelai (Glycine max L.) adalah komoditas pangan yang banyak dikonsumsi oleh masyarakat Indonesia. Tingginya kebutuhan kedelai dalam negeri membuat usaha untuk meningkatkan produksi sangat dibutuhkan. Salah satu caranya dengan meningkatkan kesuburan tanah melalui pemupukan. Penelitian ini bertujuan mengetahui pengaruh dosis pupuk kimia dan penambahan pupuk hayati terhadap pertumbuhan dan produksi tanaman kedelai. Penelitian dilakukan di Kebun Percobaan IPB Sawah Baru dari bulan November 2023 hingga Maret 2024. Percobaan menggunakan rancangan Split-Plot RKLT dengan dua faktor yaitu faktor pupuk kimia sebagai petak utama dengan dua taraf, yaitu 50% (K1) dan 100% (K2) dosis dan faktor pupuk hayati sebagai anak petak dengan 5 taraf, yaitu tidak diberi pupuk hayati (H0), pupuk hayati jenis 1 (H1), pupuk hayati jenis 2 (H2), pupuk hayati jenis 3 (H3) dan pupuk hayati jenis 4 (H4). Perlakuan 100% dosis pupuk kimia dapat meningkatkan jumlah daun 8 MST, jumlah cabang 8-10 MST, nilai kehijauan daun, nilai indeks luas daun, bobot brangkasan, jumlah polong dan biji per tanaman, bobot biji per tanaman dan bobot 100 butir. Sementara pupuk hayati jenis 4 dapat meningkatkan jumlah cabang 6-8 MST, jumlah polong dan biji per tanaman, serta indeks luas daun tetapi tidak berbeda nyata dengan pupuk hayati jenis 1,2,3, dan kontrol., Soybeans (Glycine max L.) are a commodity that is widely consumed by Indonesian people. The high level of demand for soybeans in Indonesia make efforts to increase production is necessary. One of the ways to increase soil fertility through fertilizing with biological fertilizer. This research aims to determine the effect of chemical fertilizer doses and the addition of biological fertilizer on the growth and production of soybean plants. The research was conducted at the IPB Sawah Baru Experimental station from November 2023 to March 2024. The experiment used a Split-Plot RCBD design with two factors, namely the chemical fertilizer factor as the main plot with two levels, namely 50% (K1) and 100% (K2) of the dose. optimum and biofertilizer factors as sub-plots with 5 levels, namely no biofertilizer (H0), type 1 biofertilizer (H1), type 2 biofertilizer (H2), type 3 biofertilizer (H3) and type 4 biofertilizer (H4). Treatment 100% dose with chemical fertilizer can increase the number of leaves 8 WAP, number of branches 8-10 WAP, leaf greenness value, leaf area index, dry weight of stover, number of pods per plant, number of seeds per plant, weight of seeds per plant, number of 100 grains. Type 4 biological fertilizer can increase the number of branches 6-10 WAP, number of pods per plant, leaf area index, and number of seeds per soybean plant but is not significantly different from the type 1,2,3 biofertilizer and control.
Keyword: Pupuk hayati, Produksi, detap 1

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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