Judul: Pengaruh Pemberian Ekstrak Bahan Organik Dari Kompos Kotoran Sapi, Kompos Kotoran Ayam Dan Larutan Bahan Humat Terhadap P Tersedia Pada Andisol Sukamantri Dan Inceptisol Dramaga
Abstrak: Fosfor merupakan salah satu unsur yang ketersediaannya untuk tanaman tergolong rendah. Masalah kekurangan P ini seringkali bukan hanya disebabkan oleh rendahnya kadar P total di dalam tanah, tetapi juga karena bentuk-bentuk fosfor yang dapat diambil oleh tanaman terbatas jumlahnya. Penelitian ini bertujuan untuk mengetahui pengaruh pemberian bahan organik dalam bentuk cair, yaitu ekstrak dari kompos kotoran ayam (KA), ekstrak kompos kotoran sapi (KS), dan larutan bahan humat terhadap jumlah ketersediaan fosfor pada tanah Andisol dan Inceptisol. Penelitian dilakukan dengan pemberian ekstrak kompos KA dan kompos KS dengan perbandingan tanah terhadap ekstrak kompos (1:10) dan perbandingan tanah terhadap larutan bahan humat (1:4). Tanah yang digunakan adalah Andisol Sukamantri dan Inceptisol Dramaga. Tanah dan ekstrak kompos diinkubasi selama 7 hari. Analisis P tersedia dilakukan dengan menggunakan metode Bray 1. Ekstrak kompos KA dan kompos KS berturut-turut mengandung P total sejumlah 143.4 ppm dan 102.5 ppm. Hasil analisis menunjukkan pemberian ekstrak kompos KA dan ekstrak kompos KS meningkatkan ketersediaan P pada Andisol dan Inceptisol. Setelah pemberian kompos KA dan kompos KS, pada Andisol ketersediaan P meningkat dari 6.5 ppm menjadi berturut-turut 74 ppm dan 108 ppm, sedangkan pada Inceptisol meningkat dari 5.7 ppm menjadi berturut-turut 146 ppm dan 250 ppm. Pemberian larutan bahan humat A dan B pada Andisol meningkatkan P tersedia dari 6.5 ppm menjadi 15 ppm dan 16 ppm, sedangkan pada Inceptisol meningkat dari 5.7 ppm menjadi 30 ppm dan 17 ppm
Keyword: Andisol, bahan humat, ekstrak bahan organik, kompos kotoran ayam, kompos kotoran sapi, Inceptisol, P tersedia

Judul: Pengaruh Pemberian Ekstrak Bahan Organik dari Kompos Kotoran Ayam, Kompos Kotoran Sapi dan Larutan Bahan Humat terhadap Fosfor Tersedia pada Inseptisol Dramaga dan Inseptisol Surade
Abstrak: Phosphorus (P) is an essential macro-nutrient for plant growth and development. Phosphorus problems in the soils are the small amount of P content and low availability because of high fixation. This research was aimed to find out the influence of applying organic matter extract from chicken manure compost, cow manure compost and solution of humate materials on the amount of available P in Dramaga Inceptisol and Surade Inceptisol. In this research, organic matter extract from chicken manure compost (1:10), cow manure compost (1:10), and solution of humate materials (1:4) were added to Dramaga Inceptisol and Surade Inceptisol. Analysis of available P was conducted using Bray I methods. The results analysis showed that available P were increased by adding chicken manure compost extract and cow manure compost extract. Addition of extract from chicken manure compost and cow manure compost which contained P of 1.43 ppm and 1.02 ppm each has increased available P in Dramaga Inceptisol from 5.3 ppm on control sample to 163 ppm and 216 ppm. The same treatment also increased available P in Surade Inceptisol from 4.8 ppm on control sample to 142 ppm and 179 ppm. Addition solution of humate materials A and B that containing P in Dramaga Inceptisol successfully increased available P from 5.3 ppm on control sample to 44 ppm and 35 ppm, and available P in Surade Inceptisol increased from 4.8 ppm on control sample to 26 ppm and 30 ppm.
Keyword: humate materials, cow manure compost, chicken manure compost, organic matter extract, Inceptisol, available P

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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