Judul: Identifikasi Status Ketersediaan Boron pada Tanah di Beberapa Daerah di Indonesia.
Abstrak: Pemupukan unsur hara mikro sering diabaikan, sehingga mengakibatkan defisiensi unsur hara mikro. Boron (B) merupakan salah satu unsur hara mikro dengan tingkat kejadian defisiensi yang tinggi. Penelitian ini bertujuan mengevaluasi dan mengidentifikasi status ketersediaan B pada tanah di beberapa daerah di Indonesia. Identifikasi ketersediaan B pada tanah di Indonesia menggunakan contoh tanah yang diambil secara random dari 23 lokasi. Contoh tanah kemudian dikering-udarakan, contoh tanah yang sudah siap kemudian di ekstrak menggunakan dua metode yaitu ekstraksi CaCl2 0,02 M panas dan metode ekstraksi Morgan, dengan metode kolorimetri menggunakan metode kurkumin. Hasil penelitian menunjukkan ketersediaan B dengan ekstrasi CaCl2 0,02 M panas memiliki nilai yang rendah, dan hanya sebagian kecil memiliki nilai ketersediaan B pada kelas sedang, tidak ada tanah dengan ketersedian B > 1 ppm. Lokasi dengan nilai ketersediaan B sangat rendah yaitu Grobogan, Bangli, Karawang, Semarang, dan Garut, sedangkan lokasi dengan nilai ketersediaan B rendah yaitu Subang, Cikabayan, Bandung, Mojokerto, Pesisir Barat, Ngampuang Jombang, Banjar Agung Jombang, pesisir selatan, Lahat, Banten, Bojonegoro, dan Boyolali, dan ketersediaan B pada kelas sedang terdapat pada contoh tanah dari lokasi Pati, Jasinga Bogor, Labuhan Batu Utara, Padaluyu, Cisarua Bogor, dan Sorowako. Jika nilai kelas ketersediaan B disajikan dalam persentase didapatkan hasil, kelas sangat rendah sebesar 21,7 %, kelas rendah sebesar 52,2 % dan kelas sedang sebesar 26,1 %, tidak ada tanah yang tergolong ke dalam kelas tinggi. Hal tersebut menunjukan ketersediaan B pada tanah di beberapa daerah di Indonesia tergolong rendah, hal ini cukup mengindikasikan tanah di Indonesia mengalami masalah ketersediaan B yang serius.
Keyword: Defisiensi Boron, Metode ekstraksi Morgan, Pemupukan Unsur Hara

Judul: Analsis Status Hara Fosfor Pada Berbagai Lahan Pertanian Pangan di Pulau Jawa
Abstrak: Indonesia is an agricultural country that has the fourth largest population in the world with 237,6 million people and growth rate of 1,49%. One program that made by the government to fulfill the demands of food is agricultural intensification program. While using the improved varieties, fertilizing is one of the most important input to succed this program. In Indonesia, P fertilizer is the second most important after N fertilizer, especially on up land. Availability of phosphorus in the soil becomes very important because it has many roles in plants. However, in the soil, their availability relatively low because of binding by Al, Mn and Fe in acid soils, or by Ca, Mg in alkaline soil. Since it is easily fixed and the presence of P in the soil is limited but needed in large quantities, the role of P fertilizer is critical in maintaining the availability of P nutrient for plant growth. The phenomenon levelling off, which is the rate of increase in soil productivity is not in line with the rate of fertilizer is the main reason to evaluate the status of the current P nutrient in agricultural soils in Java. This study aimed to evaluate the status of the current P nutrient (available-P and potential-P) in agricultural lands in Java, and their association with some other soil chemical properties. There are 43 samples (locations) were taken from the island of Java, which consists of 23 samples of paddy field and 20 samples of up land agriculture. The methods that used to measure the potential-P is HCl 25% extraction and the available-P is Bray 1. The results based on the available criteria show that from 23 samples of paddy field, 19 samples have very high status of potential-P, two samples have high status and two other samples have low status of potential-P. In the paddy field available-P there are 21 samples that have very high status and two other samples that have high and low status of available-P. On up land agriculture, from 20 samples, 15 samples have very high status of potential-P, four samples have high status and one other sample have medium status. Available-P in up land agriculture entirely have very high status. For paddy field there are positive correlations between available-P with exch-Ca, and pH, meanwhile on up land agriculture, potential-P has positive correlations with total-C, total-N, and EC. From this study, it is concluded that the status of P in agricultural soil in Java is in general very high. In the future, it is worthed to consider how to harvest especially the potential-P for plant growth.
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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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