Judul: Analysis Biological and Chemical Characteristics of Soil in Several Types Land Use in Bogor Regency
Abstrak: Penggunaan lahan di Kabupaten Bogor memiliki vegetasi beragam dan karakteristik tanah berbeda. Karakteristik tanah memiliki pengaruh terhadap pengelolaan lahan. Keberadaan mikrob tanah dapat digunakan sebagai bioindikator kesuburan tanah. Kesuburan tanah dihasilkan oleh interaksi sifat fisik, kimia, dan biologi tanah. Penelitian ini bertujuan mengetahui karakteristik sifat biologi dan kimia tanah pada berbagai tipe penggunaan lahan di Kabupaten Bogor. Pengambilan sampel tanah dilakukan dengan menggunakan metode purposive random sampling dengan 5 kali ulangan. Lokasi penelitian meliputi delapan penggunaan lahan yaitu kebun bambu, kebun jabon, kebun sengon, kebun lamtorogung, tegalan, tanaman sereh wangi, kebun buah naga, dan kebun pisang. Hasil analisis menunjukkan lahan pisang dan buah naga memiliki kadar C-organik, N-total tertinggi dan populasi fungi tertinggi yaitu 3,78 x 105 CFU/gram. Sedangkan pada lahan di Kecamatan Jasinga yang memiliki hara dan populasi fungi yang cukup dan populasi Azotobacter tertinggi yaitu pada lahan lamtorogung dapat diusahakan untuk tanaman perkebunan yang lebih memiliki nilai jual lebih tinggi seperti pada lahan tegalan dapat ditanami pohon karet, kelapa sawit, atau kakao., Land use in Bogor Regency has diverse vegetation and different soil characteristics. Soil characteristics have an influence on land management. The presence of soil microbes can be used as bioindicators of soil fertility. Soil fertility is produced by the interaction of physical, chemical, and biological properties of the soil. This study aims to determine the characteristics of the biological and chemical properties of soil in various types of land use in Bogor Regency. Soil sampling using the purposive random sampling method with 5 repeats. The research location includes eight land uses, namely bamboo, jabon, sengon, lamtorogung gardens, moorings, fragrant lemongrass plants, dragon fruit orchards, and banana gardens. The results of the analysis showed that banana and dragon fruit fields had the highest C-organic, N-total levels and the highest fungi population of 3,78 x 105 CFU/gram. Meanwhile, on land in Jasinga District which has sufficient nutrients and fungi populations and the highest Azotobacter population, namely on lamtorogung land, it can be cultivated for plantation crops that have a higher selling value, such as in moorlands that can be planted with rubber trees, oil palm, or cocoa.
Keyword: Azotobacter sp., microbes, soil fertility, total fungi

Judul: Analysis of soil Chemical and Biological Characteristics of Soil in Several Types Land Use in Sulawesi Tengah
Abstrak: Penggunaan lahan yang beragam serta pengelolaan yang intensif mengakibatkan penurunan tingkat kesuburan tanah di suatu lahan. Penggunaan lahan di Sulawesi Tengah banyak difungsikan sebagai perkebunan dan pertambangan sehingga populasi mikrob di setiap penggunaan lahannya berbeda-beda. Penelitian ini bertujuan mengetahui karakteristik sifat kimia dan sifat biologi tanah pada berbagai penggunaan lahan di Sulawesi Tengah. Pengambilan sampel tanah dilakukan dengan menggunakan metode purposive random sampling di Sulawesi Tengah. Lokasi penelitian yaitu Kecamatan Lore Utara dan Mantikulore (pertambangan emas), Kecamatan Nokilalaki (Kakao), dan Kecamatan Banawa Selatan (Kelapa Sawit). Hasil analisis menunjukkan populasi mikrob dan fungi tertinggi terdapat pada penggunaan Lahan Sawit yang memiliki kadar C-organik yang rendah dan kadar N-total yang sedang. Sedangkan populasi mikrob dan fungi terendah terdapat pada lahan Tambang Konvensional dengan kadar C-organik dan N-total yang rendah. Berdasarkan hasil analisis kimia tanah, Lahan Kakao memiliki kadar C-organik dan N-total lebih tinggi di antara penggunaan lahan lain, sedangkan kadar P dan K total t e r t i n g g i dimiliki oleh lahan Tambang Konvensional. Kadar C-organik dan nisbah C/N tanah berpengaruh terhadap tinggi rendahnya nilai respirasi yang dihasilka, Land use diversity and land management intensively have decreased soil fertility. One of the dominant land uses in Central Sulawesi are plantations and mining, which has an impact on the microorganism’s population. This study was aimed to determine the characteristics of chemical and biological properties of soil in various land uses in Central Sulawesi. Soil sampling was carried out using the purposive random sampling method in Central Sulawesi. The research location are North Lore District and Mantikulore District (Mining), Nokilalaki District (Cocoa), and South Banawa District (Oil Palm). The results showed that the highest concentrations of bacteria and fungi population was Oil Palm plantations which has low C-organic levels and moderate total N levels, the lowest bacterial and fungal populations was Conventional Mining with low levels of organic C and total N. Based on soil chemical properties, Cacao land has the highest content of C-organic and the total N, otherwise Conventional mining has the highest Phosphate and Potassium content. Meanwhile, C-organic and C/N ratio of soil have an effect to the high and low value of the soil respiration.
Keyword: Cocoa, C/N ratio, Gold mining, Oil Palm, Plantation

Judul: Truncated Stop Loss as a Optimal Solution of Reinsurance Agreement in One-Period Model
Abstrak: Reinsurance is one of risk management efforts of an insurance company, which is called the cedent. Similar with insurance, reinsurance constitutes the cedent to pay the premium. We consider one-period reinsurance model and derive a rule which minimizes the ruin probability of the cedent for a fixed reinsurance premium. Therefore, it is needed to construct an optimal reinsurance agreement for the cedent. The premium is calculated according to four different principles, i.e. economic, generalized zero-utility, Esscher, and mean-variance principles. Stop loss is a reinsurance contract which protect the insurance company for losses that exceed a certain amount. The result of this research shows that a truncated stop loss is an optimal agreement in the class of all reinsurance contracts with various premiums calculated using above mentioned principles.
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