Judul: Pengaruh Aplikasi Senyawa Humat Terhadap Sifat Kimia Tanah Vertisol dan Pertumbuhan Tanaman Jagung (Zea mays).
Abstrak: Vertisol is one of the potential soil type that can be used for agriculture activity intensively. This soil has high pH, cation exchange capacity (CEC), and base saturation percentage, but it has high potassium fixation that causes inefficiency in fertilization. Vertisol is considered as fertile soils, large cracks and hard soil consistency in drought seasons, sticky consistency in rainy seasons, and high potassium fixations are problems that are considered serious if the soil is used for the agriculture land. The purpose of this research are to find out the effects of applications of several dosages of humic substance to the chemical properties of vertisol, also the effects of applications of humic substance to the growth of the corn plant. This research was done in the green house university farm of Bogor Agriculture University. This research was done since September 2008 until February 2009. Soil analysis was done in the laboratory of land physical resource development, laboratory of physics and soil conservation, and laboratory of chemistry and soil fertility, Soil Science and Land Resource Department, Faculty of Agriculture, Bogor Agriculture University. Soils are applied with dosages of humic substance which are H0 (0 l/ha), H1 (5 l/ha)), H2 (10 l/ha), dan H3 (25 l/ha). The results of this research showed that addition of humic substance does not gives a significant increase to the soil chemical properties of vertisol generally. Soil acidity (pH) showed a relatively same value in all dosages that which were 7,49 - 7,51. Base saturation that was also analyzed in each application showed a percentage of >100%., where bases that analyzed were dominated by Ca and Mg Cations. CEC showed a small increase for all treatment. The highest increase of CEC is in H1 which is 30,76 me/100g from control which is 27,92 me/100g. C-organic showed a relatively same value for each application which is in the range of 1,05% in H1 and 1,22% in H3. Application of humic substance showed an increase in plant height, wet mass, and dry mass. But showed the same value relatively in the numbers of leaves of the corn.
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Judul: Pengaruh aplikasi polimer hidroksi aluminium terhadap beberapa sifat kimia tanah vertisol dan pertumbuhan jagung [Zea mays]
Abstrak: Salah satu lahan pertanian yang memiliki potensi untuk dimanfaatkan secara lebih intensif adalah tanah-tanah yang termasuk ke dalam ordo Vertisol dan tanah-tanah lainnya yang memiliki sifat vertik. Dari sisi sifat kimia tanah ini memiliki pH, kapasitas tukar kation dan persentase kejenuhan basa yang tinggi. Meskipun Vertisol tergolong subur, retakan yang hebat, konsistensi tanah sangat keras pada musim kemarau, sangat lekat pada musim hujan dan fiksasi kalium yang tinggi merupakan kendala-kendala yang cukup serius bila tanah ini dimanfaatkan untuk keperluan pertanian. Untuk memperbaiki kualitas sifat fisik dan kimia tanah ini, aplikasi polimer hidroksi aluminium bisa menjadi salah satu yang diharapkan. Penelitian ini bertujuan untuk mengetahui pengaruh aplikasi Polimer Hidroksi Aluminium (PHA) terhadap beberapa sifat kimia tanah Vertisol yaitu kemasaman (pH), kapasitas tukar kation (KTK) dan kejenuhan basa-basa (KB), serta pertumbuhan jagung sebagai tanaman indikator.
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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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