Judul: Comparative Feasibility Study of Rubber Agroforestry Business in Pelaihari Unit, Tanah Laut Regency, South Kalimantan
Abstrak: Pembangunan agroforestri sudah cukup lama dilaksanakan di Indonesia. Namun, sampai saat ini masih banyak tantangan pengelolaannya, salah satunya informasi skema agroforestri terbaik pada hutan tanaman industri yang masih terbatas. Pemanfaatan hutan karet di Unit Pelaihari Kabupaten Tanah Laut, Kalimantan Selatan milik PT. Inhutani III dikelola oleh dua perusahaan dengan skema agroforestri. Untuk itu, penelitian ini bertujuan menganalisis kelayakan finansial skema agroforestri yang telah dipraktikkan tersebut. Berdasarkan perhitungan analisis finansial, pengelolaan agroforestri karet, baik dengan tanaman sela singkong ataupun jagung adalah layak diusahakan. Namun, pada perbandingan per hektar usaha agroforestri karet, tanaman singkong memberikan nilai NPV, IRR, dan jangka waktu pengembalian (payback period) yang lebih baik dibanding tanaman jagung. Untuk itu, skema agroforestri karet layak diusahakan untuk pengembangan usaha, terutama dengan tanaman sela singkong. Manfaat yang didapat dari tumpangsari tidak hanya sebagai tanaman menghasilkan disaat tanaman utama belum menghasilkan, tetapi dapat meningkatkan pendapatan maksimum., Agroforestry development has been implemented in Indonesia for quite a long time. However, there are still many management challenges, one is the lack of information on the best agroforestry schemes in industrial plantation forests. PT. Inhutani III, in the Pelaihari Unit of Tanah Laut Regency, South Kalimantan, cooperates with two companies to utilize rubber forests under agroforestry schemes. In response, this study aimed to analyze the financial feasibility of the agroforestry scheme that has been practiced. Based on financial analysis, the management of rubber agroforestry with cassava or corn intercropping was feasible. However, in the ratio per hectare of rubber agroforestry business, cassava crops provided better NPV, IRR, and payback period values than corn crops. For this reason, the rubber agroforestry scheme is worth striving for business development, especially with cassava intercropping. The benefits derived from intercropping are not only as a yielding crop when the main crop is not yet harvested but can increase maximum income.
Keyword: agroforestry, financial analysis, plantation forest

Judul: Financial Feasibility Analysis of Rubber and Oil Palm Farming in Dolok Masihul District, Serdang Bedagai Regency, North Sumatera Province
Abstrak: Upaya Kabupaten Serdang Bedagai dalam meningkatkan luas lahan kelapa sawit memiliki persaingan dengan komoditas karet. Tanaman karet merupakan tanaman yang diusahakan secara turun temurun. Petani tidak memiliki catatan history tentang usahatani karet dan kelapa sawit sehingga tidak diketahui secara pasti manakah usahatani yang lebih layak untuk dijalankan. Penelitian ini bertujuan untuk (1) Mengidentifikasi aspek-aspek kelayakan dan mengestimasi kelayakan finansial usahatani karet dan kelapa sawit di Kecamatan Dolok Masihul (2) Menganalisis switching value dan sensitivitas perubahan harga jual output dan harga beli input pada usahatani karet dan kelapa sawit di Kecamatan Dolok Masihul dan (3) Menganalisis persepsi petani terhadap usahatani karet dan kelapa sawit di Kecamatan Dolok Masihul. Metode dalam penelitian ini adalah analisis deskriptif, analisis kelayakan finansial, analisis switching value, analisis sensitivitas dan analisis likert. Hasil penelitian menunjukkan usahatani karet dan kelapa sawit layak untuk dijalankan. Berdasarkan kriteria investasi menunjukkan usahatani kelapa sawit lebih menguntungkan dibandingkan dengan usahatani karet. Analisis switching value dan sensitivitas menunjukkan bahwa adanya perubahan harga output dan input mempengaruhi pendapatan petani karet dan kelapa sawit. Alasan yang mempengaruhi petani untuk tetap berusahatani karet antara lain usahatani karet adalah usahatani yang dilakukan secara turun temurun, pendapatan usahatani karet masih dapat memenuhi kebutuhan hidup sehari-hari, dan petani nyaman dalam berusahatani karet., The efforts of Serdang Bedagai Regency in increasing the area of oil palm land have competition with rubber commodities. Rubber plant is a plant that is cultivated from generation to generation. Farmers do not have historical records of rubber and oil palm farming so it is not known for sure which farming is more feasible to run. This study aims to (1) Identify the feasibility aspects and estimate the financial feasibility of rubber and oil palm farming in Dolok Masihul District (2) Analyze the switching value and the sensitivity of changes in the selling prices of output and the purchase price of inputs on rubber and oil palm farming in Dolok Masihul District and (3) Analyze farmers’ perceptions of rubber and oil palm farming in Dolok Masihul District. The methods in this research are descriptive analysis, financial feasibility analysis, switching value analysis, sensitivity analysis and likert analysis. The result showed that rubber and oil palm farming was feasible 94 to run. Based on the investment criteria, it shows that oil palm farming is more profitable than rubber farming. Switching value analysis and sensitivity analysis shows that changes in output and input prices affect the income of rubber and oil palm farmers. The reasons that influence farmers to continue farming rubber are: rubber farming has been carried out from generation to generation, rubber farming income can still meet the needs of daily life, and farmers are comfortable in rubber farming.
Keyword: welfare, conversion, cultivation, production, profit

Judul: Metrik Einstein (Anti-) Self-Dual Berdimensi Empat dengan Metode Cartan
Abstrak: Gravitational field equation can be formulated in differential forms (differential geometry), which describes gravity as a manifestation of the curvature of space-time. Curvature of space-time is characterized by a metric that satisfies the gravitational field equation. With differential forms it can be formulated the (anti-) self-dual Einstein equation, which is a modification of the Cartan structure in (anti-) self-dual basis. Calculation of (anti-) self-dual metric with (anti-) self-dual Einstein equation is simpler than the calculation using Christoffel symbols.
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