Judul: Analisis Sebaran Pupuk Butiran pada Berbagai Metode Penebaran Pupuk Secara Manual di Lahan Sawah Oleh Petani
Abstrak: Most of Indonesian rice farmers apply fertilizers manually. The distribution of fertilizers is unknown, so it is necessary to find a method to determine the variability of fertilizer distribution. In this research, several combinations of spreading ways were analyzed to determine the variability of fertilizer distribution. The research began with identification patterns of fertilizer spreading by farmers. Simulation of the spreading pattern was done by spreading fertilizer on a plastic sheet covered by a glue layer. Images from of the fertilizer on the plastic sheet are taken and analyzed to predict the fertilizer distribution. The results of simulation showed that the distribution of fertilizer vary within a wide range of 470 kg/ha to 940 kg/ha, and the average is 651.20 kg/ha. Simulation also found the best combination of spreading pattern that could achieve a relatively uniform distribution with the range of dosage 125.79 kg/ha to 940.05 kg/ha and the average is 151.98 kg/ha.
Keyword: simulation, image processing, fertilizer spreading

Judul: Analysis of Nutrient Availability Map and Nutrient Needs Map  of Glutinous Rice Plants Based on Optimum Percentage Deviation Method
Abstrak: Umumnya pemupukan yang dilakukan sebagian besar petani padi ketan di Kabupaten Subang belum menggunakan pupuk sesuai kebutuhan tanaman. Penentuan kebutuhan pupuk padi ketan bisa dilakukan dengan mengetahui ketersediaan unsur hara tanah dan kebutuhan unsur hara tanaman. Data ketersediaan unsur hara tanah diketahui dengan melakukan analisis tanah berupa N-Tersedia, Fosfor (P), dan Kalium (K). Kebutuhan unsur hara tanaman diukur menggunakan metode DOP (Deviation Of Optimum Percentage). Pembuatan peta ketersediaan dan kebutuhan unsur hara dilakukan dengan metode interpolasi Kriging. Penelitian ini bertujuan membuat peta ketersediaan unsur hara, kebutuhan unsur hara tanaman dan membandingkan kedua peta tersebut. Berdasarkan hasil peta ketersediaan unsur hara tanah didapatkan persebaran pola unsur hara (N), (P), dan (K) yang bervariasi. Uji keakuratan model dengan menghitung nilai RMSE (Root-Mean-Square Error) dan Mean Absolute Error (MAE), dihasilkan nilai RMSE dan MAE paling akurat pada unsur hara (P) yaitu 6,3 dan 5,2. Berdasarkan indeks DOP, dihasilkan urutan kebutuhan pemupukan dari yang paling dibutuhkan, seperti perhitungan elevasi rendah 6,87 – 18,24 mdpl unsur hara (N) lebih dibutuhkan dari pada unsur (K) dan (P). Berdasarkan hasil perbandingan persentase per hektar peta ketersediaan dan kebutuhan unsur hara dihasilkan kesesuaian perbandingan pola ketersediaan rendah = kebutuhan tinggi yaitu 7,0 % (N), 2,6 % (P), dan 0,6 % (K). Sedangkan kategori tidak sesuai mendominasi pola perbandingan peta ketersediaan dan kebutuhan unsur hara yaitu 51,4 % (N), 79 % (P), dan 63,4 % (K)., In general, most of the glutinous rice farmers in Subang Regency fertilize without using fertilizer according to the needs of the plants. Determining the need for glutinous rice fertilizer can be done by knowing the availability of soil nutrients and plant nutrient requirements. Data on the availability of soil nutrients is known by conducting soil analysis in the form of Available-N, Phosphorus (P), and Potassium (K). The need for plant nutrients is measured using the DOP (Deviation Of Optimum Percentage) method. Making maps of nutrient availability and needs is done by the Kriging interpolation method. This study to make a map of nutrient availability, plant nutrient needs and compare the two maps. Based on the results of the soil nutrient availability map, it was found that the distribution of nutrient patterns (N), (P), and (K) varied. Test the accuracy of the model by calculating the RMSE (Root-Mean-Square Error) and Mean Absolute Error (MAE) values, resulting in the most accurate RMSE and MAE values for nutrients (P), namely 6,3 and 5,2. Based on the DOP index, the sequence of fertilization needs is generated from the most needed, such as the calculation of low elevations 6,87 – 18,24 masl nutrients (N) are more needed than elements (K) and (P). Based on the results of a comparison of the percentage per hectare map of nutrient availability and requirements, a suitability of the pattern of low availability = high demand was obtained, namely 7.0% (N), 2.6% (P), and 0.6% (K). Meanwhile, the unsuitable category dominates the comparison pattern of nutrient availability and requirement maps, namely 51.4% (N), 79% (P), and 63.4% (K).
Keyword: Accuracy test, availability, fertilization, kriging interpolation, needs

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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