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: Spatial Distribution of Soil Nutrients in Sawah Baru Agriculture Fields, Dramaga District, Bogor Regency
Abstrak: Tanaman padi merupakan komoditas pangan utama yang dikonsumsi masyarakat Indonesia. Kabupaten Bogor salah satu wilayah yang berkontribusi signifikan dalam memenuhi kebutuhan komoditas padi di Jawa Barat dan sekitarnya. Akan tetapi, masih terdapat permasalahan pada penurunan produksi, produktivitas dan luas panen lahan padi sawah. Pemanfaatan metode interpolasi Ordinary Kriging bagi lahan sawah di Indonesia masih sangat minim, terutama informasi status hara pada lahan pertanian di Kabupaten Bogor. Penelitian ini bertujuan untuk menganalisis, memetakan, dan membandingkan pola spasial parameter kesuburan tanah (pH H2O, C-organik, dan status hara tanah) pada tanaman padi menggunakan metode Kriging di Lahan Sawah Baru Dramaga, Kabupaten Bogor. Hasil penelitian menunjukkan keragaman semivariogram dari setiap parameter kesuburan tanah (pH H2O, C-organik, N-total, P-tersedia, P-total, K-total, yang dapat ditukar (Ca-dd, Mg-dd, K-dd, Na), KTK dan KB) yang dikuantifikasi dari nugget effect, sill, dan range dalam semivariogram. Distribusi spasial beberapa parameter kesuburan tanah di wilayah penelitian bervariasi dengan rentang dari sangat rendah sampai dengan sangat tinggi dengan akurasi berbeda. Pemetaan dengan metode interpolasi Ordinary Kriging melalui semivariogram spherical juga menunjukkan tingkat akurasi berbeda. Parameter pH H2O, K-total, Ca-dd, dan Mg-dd mempunyai akurasi yang lebih kuat serta parameter P-total dan Kdd mempunyai akurasi yang moderat dibandingkan parameter lain. Sedangkan, parameter C-organik, P-tersedia, N-total, Na-dd, KTK, dan KB mempunyai akurasi yang lebih lemah menunjukkan parameter tersebut kurang akurat dalam menggambarkan kondisi aktual wilayah penelitian., Rice is a main food commodity consumed by Indonesians. Kabupaten Bogor is one of the regions that significantly contributes to West Java’s demand. However, problems in production decrease, productivity, and total harvested paddy field have widely been acknowledged, whilst land resource datasets have largely been insufficient. This research assessed ordinary kriging interpolation, which has been limitedly investigated on the retrievals of soil nutrients. This research goal was to analyze, to map, and to compare spatial pattern of soil fertility parameters (pH H2O, soil organic carbon (OC), and soil nutrient status). Experiment was conducted in Sawah Baru agriculture fields, Kecamatan Dramaga, Kabupaten Bogor. Results showed a variety of semivariogram, observed from soil fertility parameters (i.e., pH H2O, soil organic carbon (OC), Total-N, P-Available, Total-P, Total-K, Exchangeable Ca, Mg, K, Na, cation exchange capacity (CEC), and base saturation), with respect of nugget effects, sills, and ranges in respective semivariograms. Spatial distribution of soil fertility parameters broadly varied with divergent accuracies. Modeling using spherical-type semivariogram also indicated unassociated levels of accuracy. pH H2O, Total-K, Exchangeable Ca, and Exchangeable Mg were parameters with strong accuracy levels, while Total-P and Exchangeable K displayed moderate accuracy compared to other parameters. Meanwhile, soil organic carbon (OC), P-Available, Exchangeable Na, CEC and base saturation indicated a lower accuracy, suggesting that those parameters warrant an in-depth analysis in the future.
Keyword: Ordinary Kriging, kesuburan, semivariogram, fertility

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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