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: Peranan Cacing Tanah sebagai Bioindikator Kesuburan Tanah pada Berbagai Tipe Tutupan Lahan di Dramaga Bogor
Abstrak: Rapid population growth accompanied by improved quality of life for the better cause of human dependence on natural resources increases. In a natural resource ecosystems, plants have an important role in maintaining the ecological functions of ecosystems natural resources through its ability to regulate micro-climate conditions, water management and soil fertility. Soil fertility is the ability of the soil provides nutrients for plant growth. In this case, the earthworm is one of the terrestrial ecosystem biotic factors that served to increase soil fertility. The role of earthworms are very important for the process of decomposition of soil organic matter significantly affect the soil fertility. Research aims: (1) determine the type of land cover in Dramaga, (2) identify and analyze the various types of plants on land cover, (3) analyzing the fertility of the soil on the following types of land cover history management, (4) identify the type and abundance suspect earthworms as indicators of soil fertility, and (5) examine the relationship of the abundance of earthworms in soil fertility and plant abundance. Research activities carried out in Dramaga, West Bogor District, West Java. The research lasted for 3 (three) months, from February to April 2013. At the study site was the interpretation of Landsat imagery to identify and interpret the land cover type (landuse) at the study site. Then on each type of land cover is an inventory / treatise against three research objects that is plants, earthworms and soil fertility. Sampling design of the study using a two stage sampling. Primary sampling units in the form of squares measuring 20 m x 20 m three units per land cover type plants to the minutes of the tree level. As for the minutes of the level of regeneration is made smaller squares by three squares units each measuring 2 m x 2 m for seedlings, 5 m x 5 m for sapling and 10 m x 10 m for the pole in each primary sampling unit. Being for the benefit of earthworms treatise made secondary sampling unit size of 1 m x 1 m by one unit per primary sampling unit. In this study the identification or interpretation of land cover types is done using ArcGIS 9 software on Landsat imagery in 2012. The analysis of vegetation data (density, frequency, dominance, importance value index) using analysis of vegetation (Misra, 1974) and species diversity are analyzed according to the Shannon-Wiener formula (Krebs, 1978), soil fertility by the Research and Development of the Agriculture Department of Agriculture, 2005 and estimate the abundance of earthworms in each land cover type calculation procedures used by two stage sampling design. Based on the results of processing of Landsat imagery in the study site using ArcGIS 9 software, there are five types of land cover that bare ground, grasses, shrubs, forest plantations, and mixed forest. Results of data acquisition fifth land cover types dominated by species of different plants, namely: Digitaria sanguinalis (L.) in grasses, Waltheria indica (L.) in the bush, in Tectona grandis plantations, as well as Mimosa pudica (undergrowth), Hopea bancana (sapling), Baccaurea racemosa (pole), and
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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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