Judul: Palm Oil Plantation Weed Control Management (Elaeis guineensis Jacq.) PT Supra Matra Abadi, Aek Nabara, North Sumatra
Abstrak: Pengendalian gulma merupakan kegitan penting di perkebunan kelapa sawit karena keberadaan gulma meberikan pengaruh negatif bagi perkebunan kelapa sawit akibat adanya kompetisi antara gulma dengan tanaman kelapa sawit. Kegiatan magang di kebun Aek Nabara PT Supra Matra Abadi bertujuan meningkatkan kemampuan kerja secara teknis dan manajerial, serta mempelajari manajemen pengendalian gulma perkebunan. Kegiatan magang dilaksanakan pada bulan Januari hingga Mei 2021. Metode yang digunakan adalah metode langsung (data primer) dan tidak langsung (data sekunder). Pengamatan analisis vegetasi menunjukkan bahwa gulma Asystasia gangetica merupakan gulma dominan di areal TBM dan TM muda dengan nilai SDR sebesar 38,69% dan 30,20%. Gulma Centotheca lappacea merupakan gulma dominan di areal TM tua dengan nilai SDR sebesar 43,57%. Estimasi biaya pengendalian gulma ha-1 tahun-1 mencapai Rp. 1.113.000,00 untuk biaya herbisida dan Rp. 294.291,00 untuk biaya HK. Prestasi tenaga kerja di Kebun Aek Nabara adalah 0,16 ha HK-1 . Persentase tingkat penggunaan APD di Aek Nabara cukup rendah yaitu 75,6% hal ini diduga karena kacamata safety googles tidak digunakan sama sekali dalam proses penyemprotan. Kata kunci: Analisis vegetasi, APD, CDA, estimasi biaya, prestasi kerja., Weed control is an important activity in oil palm plantations because the presence of weeds has a negative influence on oil palm plantations due to competition between weeds and palm oil plants. Internship activities at Aek Nabara Plantation of PT Supra Matra Abadi aim to improve technical and managerial work capabilities, as well as study the management of plantation weed control. Internship activities are held from January to May 2021. The methods used are direct (primary data) and indirect (secondary data) methods. Observations of vegetation analysis showed that asystasia gangetica weeds are the dominant weeds in young TBM and TM areas with SDR values of 38.69% and 30.20%. Centotheca lappacea weed is the dominant weed in the old TM area with an SDR value of 43.57%. Estimation cost of weed control ha-1 year-1 reaches Rp. 1.113.000,00 for herbicide costs and Rp. 294.291,00 for HK fees. Labor performance in Aek Nabara Plantation is 0.16 ha HK-1. The percentage of APD use rate in Aek Nabara is quite low, which is 75.6% this is suspected because googles safety glasses are not used at all in the spraying process.
Keyword: APD, CDA, cost estimation, vegetation analysis, work performance

Judul: Weed Management of Oil Palm (Elaeis guineensis Jacq.) at Negeri Lama Selatan Estate, PT Hari Sawit Jaya, North Sumatera
Abstrak: Pengelolaan gulma pada kelapa sawit merupakan suatu strategi dalam kegiatan pengendalian gulma yang terdiri atas tahap perencanaan, pengawasan, dan pengontrolan untuk mencapai hasil pengendalian gulma yang efektif, efisien, dan berkelanjutan. Kegiatan magang dilaksanakan pada Januari hingga Mei 2022 yang berlokasi di Kebun Negeri Lama Selatan, PT Hari Sawit Jaya. Kegiatan magang memiliki tujuan umum dalam meningkatkan pengetahuan dan pengalaman kerja pada perkebunan kelapa sawit serta tujuan khusus dalam menganalisis jenis gulma dominan, mempelajari terkait pengelolaan pengendalian gulma dan penerapan aspek 5 tepat kelapa sawit. Hasil pengamatan diperoleh dengan menggunakan metode langsung dan tidak langsung. Hasil pengamatan data primer berdasarkan perhitungan NJD, gulma Cynodon dactylon (36,43%) dan Asystasia gangetica (25,24%) mendominasi areal tumbuh kelapa sawit. Kegiatan kalibrasi alat perlu disesuaikan dengan standar perusahaan berdasarkan hasil uji t-Student pada taraf 5%. Penerapan dosis metil metsulfuron tanaman-1 dan realisasi lebar semprot pada areal piringan dan pasar pikul sudah memenuhi standar ketepatan perusahaan berdasarkan hasil uji t-Student pada taraf 5%. Ketepatan cara semprot dan aplikasi bahan aktif sudah mencapai nilai rata-rata persentase 93,33% dan 100% yang tergolong pada tingkat yang sangat baik. Pelaksanaan waktu semprot telah terlaksana dengan tepat yang didasarkan pada sistem perencanaan yang baik. Pengelolaan gulma telah dilaksanakan dengan keberlanjutan melalui perencanaan identifikasi gulma dan jadwal pengendalian, pengawasan teknis, pengontrolan kualitas hasil pengendalian, penerapan aturan dalam penggunaan bahan kimia, dan pengoptimalan mempertahankan gulma penting (Nephrolepis biserrata) untuk habitat predator ulat api. Kematian total gulma Asystasia gangetica efektif pada hari ke-20 HSA dengan konsentrasi 0,3% metil metsulfuron. Penggunaan APD tergolong dalam kategori sangat baik berdasarkan rata-rata persentase penggunaan yang mencapai 93,33%. Keterampilan aplikasi waktu semprot dipengaruhi oleh usia berdasarkan uji F pada taraf 5%. Pengawasan terhadap kondisi alat semprot penting dilakukan untuk mengoptimalkan keefisienan penggunaan biaya pengendalian., Weed management in oil palm is a strategy in weed control consist of planning, monitoring, and controlling stages for effective, efficient, and sustainable weed control. The internship activity was carried out from January to May 2022 and it was located at Negeri Lama Selatan Estate, PT Hari Sawit Jaya. Internship activities have general goals of increasing knowledge and work experience in oil palm plantations and specific goals in analyzing dominant weed types, supervising of weed control management, and using the 5 right aspects of weed control in oil palm. Observation results were obtained using direct and indirect methods. The results of primary data observations based on NJD calculations, Cynodon dactylon (36.43%) and Asystasia gangetica (25.24%) weeds that dominated in the oil palm growing area. Calibration activities need to be adjusted to company standards based on the results of the t-student test at the 5% level. The application of metsulfuron-methyl dose of plant and spray width in the weeded circle and in row area has met the company's standard accuracy based on the results of t-student at a 5% level. The accuracy of the spray method and the application of active ingredients have reached an average percentage of 93.33% and 100% which is classified as a very good level. The implementation of the time has been carried out correctly is based on a good planning system. Weed management has
Keyword: Gulma, Kalibrasi, Keterampilan kerja, Lima tepat

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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