Judul: Analysis of Biological and Chemical Characteristics of Soil at Various Altitudes in Bandung, West Java
Abstrak: Bandung memiliki ketinggian antara 675 mdpl – 2.100 mdpl dengan suhu udara berkisar 14oC sampai dengan 30oC. Ketinggian tempat merupakan salah satu faktor yang berpengaruh terhadap pertumbuhan dan perkembangan tanaman. Perbedaan ketinggian tempat di atas permukaan laut (dpl) dapat menimbulkan perbedaan iklim dan cuaca terutama suhu dan kelembapan. Perbedaan iklim dan cuaca dapat mempengaruhi populasi mikrob dan transformasi hara di dalam tanah. Tujuan dari penelitian ini mempelajari karakteristik sifat biologi dan kimia tanah pada beberapa ketinggian tempat di Bandung, Jawa Barat. Hasil penelitian menunjukkan ketinggian tempat menghasilkan aspek kesuburan tanah berbeda. Keragaman kadar unsur hara tanah yang karena tingkat pengelolaan lahan yang berbeda-beda. Populasi bakteri pelarut fosfat (BPF) dapat tumbuh dengan optimum pada ketinggian 1000 mdpl. Nilai pH yang sesuai untuk pertumbuhan bakteri serta kandungan P-Total yang sangat tinggi dan P-tersedia yang sedang merupakan faktor BPF tumbuh dengan memanfaatkannya sebagai sumber nutrisi. Total populasi fungi tumbuh optimum hanya sampai ketinggian 1200 mdpl, sedangkan pada ketinggian 1400 mdpl populasi fungi menurun. Respirasi tanah pada ketinggian tempat memiliki nilai yang tidak berbeda nyata. Tanaman hortikultura sesuai dibudidayakan pada ketinggian 600 – 1200 mdpl, sedangkan pada ketinggian > 1200 mdpl lebih sesuai untuk tanaman perkebunan., Bandung has an altitude between 675 masl – 2,100 masl with air temperatures ranging from 14oC to 30oC. The height of the place is one of the factors that influence the growth and development of plants. Differences in altitude above sea level (asl) can cause differences in climate and weather, especially temperature and humidity. Climate and weather differences can affect microbial populations and nutrient transformations in the soil. The aims of study is to study the characteristics of soil biological and chemical properties at several altitudes in Bandung, West Java. The results showed that the height of the place produced different aspects of soil fertility. The diversity of soil nutrient levels due to different levels of management. The population of phosphate solubilizing bacteria (BPF) can grow optimally at altitude of 1000 meters above sea level. The pH value is appropriate for bacterial growth as well as the very high P-Total content and moderate P-available is a factor in BPF growing by utilizing it as a source of nutrition. The total population of fungi grows optimally only at altitude of 1200 meters above sea level, while at altitude of 1400 meters above sea level the fungi population was decreased. Soil respiration at the height of the premises has no significant different value. Horticultural crops are suitable for cultivation at altitude of 600-1200 meters above sea level, while at an altitude of > 1200 meters above sea level are more suitable for plantation crops.
Keyword: Nutrient, Phosphate Solubilizing Bacteria, Temperature, Total Fungi

Judul: Analysis of Soil Fertility at Various Level of Canopy Density in KHDTK Haurbentes, Bogor District, West Java
Abstrak: Kawasan Hutan Dengan Tujuan Khusus (KHDTK) Haurbentes merupakan kawasan hutan yang dimanfaatkan secara khusus menjadi hutan penelitian di kawasan hutan produksi. Kawasan hutan ini harus tetap memperhatikan kelestarian dan kesuburan tanahnya. Tujuan dilakukan penelitian ini adalah untuk menganalisis kesuburan tanah pada berbagai kerapatan tajuk berdasarkan sifat fisik dan kimia tanah. Kerapatan tajuk diukur menggunakan alat spherical densiometer (SD). Sampel tanah diambil di tiga titik secara diagonal pada petak berukuran 20 m × 20 m berdasarkan kerapatan tajuk rendah, sedang, dan tinggi. Parameter yang digunakan untuk menentukan kesuburan tanah yaitu tekstur tanah, pH tanah, C-organik, P2O5 potensial, K2O potensial, kation yang dapat ditukar, KTK, dan kejenuhan basa. Hasil penelitian menunjukkan bahwa kondisi tanah di bawah ketiga tutupan tajuk memiliki tekstur tanah beragam dari debu hingga lempung berpasir, pH tanah masam, C-organik, P2O5, dan kation dapat ditukar yang rendah, K2O yang sedang, dan kejenuhan basa yang rendah. Adapun nilai KTK sangat tinggi pada kerapatan tajuk rendah, sedang, dan tinggi berturut-turut adalah 50,30 me/100g, 52,96 me/100g, dan 53,93 me/100g. Status kesuburan tanah yang ditemukan pada setiap kerapatan tajuk masih tergolong rendah., Special Purpose Forest Area (KHDTK) Haurbentes is a forest area that is specifically used as a research forest in a production forest area. This forest area must still pay attention to the sustainability and fertility of the soil. The purpose of this study was to analyze soil fertility at various canopy densities based on the physical and chemical properties of the soil. The canopy density was measured using a spherical densiometer (SD). Soil samples were taken at three points diagonally on a 20 m × 20 m plot based on low, medium, and high canopy densities. The parameters used to determine soil fertility were soil texture, soil pH, organic C, potential P2O5, potential K2O, exchangeable cations, CEC, and base saturation. The results showed that the soil conditions under the three canopy covers had various soil textures from silt to sandy loam, acidic soil pH, low C-organic, P2O5, and cation exchangeability, moderate K2O, and low base saturation. As for the exceptionally high CEC values at low, medium, and high crown density were 50,30 me/100g, 52,96 me/100g, and 53,93 me/100g, respectively. Soil fertility status of the soil found at each canopy density was still relatively low.
Keyword: c-organik, hutan penelitian, kerapatan tajuk, kesuburan, KTK, c-organic, CEC, crown density, fertility, research forest

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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