Judul: Perfomance of Shallot Production at Various Levels of Soil
Pottasium Content in Andisol and Inceptisol
Abstrak: Hara merupakan faktor yang penting dalam pertumbuhan tanaman bawang merah. Salah satu hara utama yang mendukung pertumbuhan bawang merah adalah kalium. Penelitian bertujuan untuk mengetahui pertumbuhan bawang merah yang dibudidayakan pada berbagai tingkat kadar hara kalium di tanah andisol dan inceptisol. Penelitian dilakukan di Rumah Plastik Kebun Percobaan Tajur PKHT IPB, Kecamatan Bogor Selatan, Kota Bogor, Jawa Barat pada bulan Februari sampai September 2021. Metode yang digunakan pada penelitian adalah rancangan kelompok lengkap teracak (RKLT) faktorial dengan perlakuan jenis tanah dan kadar hara kalium. Peubah pengamatan yang diamati adalah tinggi tanaman, jumlah daun, jumlah anakan, rata-rata diameter, jumlah umbi per rumpun, bobot basah tanaman, bobot basah umbi, bobot kering tanaman, dan bobot kering umbi. Berdasarkan hasil penelitian didapatkan bahwa interaksi antara jenis tanah dan kadar hara K berpengaruh terhadap bobot basah tanaman, bobot basah umbi, bobot kering tanaman, bobot kering umbi. Hasil penelitian juga menunjukkan bahwa secara umum pertumbuhan bawang merah di tanah andisol lebih baik daripada di tanah inceptisol., Nutrients are an important factor in growth of shallot plants. One of the main nutrients that support the growth of shallots is potassium. The objective of this study was to find out the growth of shallots cultivated at various levels of potassium nutrients in andisol and inceptisol soils. The study was conducted at the Plastic House of Tajur Experimental Garden, PKHT IPB, South Bogor, Bogor, West Java, from February until September 2021. This study was designed according to randomized complete block design (RCBD), two factor. The factors are soil type (andisol and inceptisol) and potassium nutrient levels as treatments. The observed variables included plant height, number of leaves, number of tillers, average diameter, number of bulbs per clump, wet weight of plants, wet weight of bulbs, dry weight of plants, and dry weight of bulbs. Based on the results of the study, interaction between soil type and potassium nutrient had an effect on wet weight of plants, wet weight of bulbs, dry weight of plants, and dry weight of bulbs. The result of study also shown in general, the growth of shallot in andisol soil better than inceptisol soil.
Keyword: pottasium, allium ascalonicum, andisol, inceptisol

Judul: Batas Kritis Hara Kalium Tanah untuk Tanaman Bawang Merah di Kabupaten Brebes, Jawa Tengah
Abstrak: Bawang merah (Allium cepa) merupakan komoditas hortikultura yang memiliki nilai ekonomi tinggi dan dibutuhkan oleh masyarakat dalam jumlah yang tidak sedikit. Penanaman bawang merah di sentra produksi Kabupaten Brebes dilakukan secara intensif akan berdampak buruk jika dilakukan dalam jangka panjang. Penentuan batas kritis hara kalium (K) tanah perlu dilakukan untuk mengetahui dosis pemupukan yang tepat pada tanah di Brebes. Tujuan penelitian ini adalah menentukan metode ekstraksi K tanah terbaik, mengetahui pengaruh pemupukan K terhadap pertumbuhan bawang merah, serta menentukan batas kritis hara K tanah untuk tanaman bawang merah di 13 lokasi pengambilan contoh tanah di Kabupaten Brebes. Metode ekstraksi K terbaik ditentukan dengan nilai koefisien korelasi (r) tertinggi dan nyata. Pemupukan K dilakukan dengan memberikan KCl p.a (X) pada taraf K0= 0, K1= ½ X, K2= X, dan K3= 2X kg ha-1 dengan dosis anjuran X=200 kg ha-1. Metode penentuan batas kritis yang digunakan adalah metode grafik Cate-Nelson dengan empat metode ekstraksi K tanah yaitu HCl 25%, Bray I, NH4OAc, dan pengabuan basah. Metode ekstraksi K yang paling sesuai untuk tanah di pertanaman bawang merah pada 13 lokasi penelitian ini adalah HCl 25% karena mempunyai korelasi yang nyata dengan bobot kering tanaman perlakuan K0. Hasil analisis ragam menunjukkan bahwa dosis pemupukan tidak berpengaruh nyata pada pertumbuhan tanaman bawang merah namun faktor lokasi berpengaruh nyata terhadap pertumbuhan bawang merah. Batas kritis hara K tanah untuk mencapai 90% produksi maksimum bawang merah pada 13 lokasi penelitian di Kabupaten Brebes berdasarkan metode HCl 25% adalah sebesar 550 ppm., Shallot (Allium cepa) is a horticultural commodity with high economic value and is needed by the community in large quantities. Cultivation in center production of Brebes Regency shallot is conducted intensively that will have a negative impact if carried out in the long term. It is necessary to determine the critical level for soil potassium (K) to determine the correct fertilization dose for the soil in Brebes. This study aimed to determine the best soil K extraction method, the effect of K fertilization on shallot growth, and the critical level of soil K nutrient for shallot at 13 soil sampling locations in Brebes Regency. The best K extraction method is determined by the highest correlation coefficient (r) value. K fertilization was carried out by applying KCl p.a (X) at K0= 0, K1= ½X, K2= X, dan K3= 2X kg ha-1 with the recommended dose of X=200 kg ha-1. The critical level determination method used was Cate-Nelson graphical method with four extraction methods, namely 25% HCl, Bray I, NH4OAc, and wet ignition. The most suitable K extraction method for soils in shallot fields at 13 locations in this study was 25% HCl because it significantly correlated with the dry weight plants of K0 treatment. The analysis of variance showed that the fertilization dose did not significantly affect the growth of shallot, but the location factor had a significant effect on shallot growth. The critical level for soil K nutrients to achieve 90% of the maximum shallot production at 13 research locations in Brebes Regency based on the 25% HCl method is 550 ppm.
Keyword: batas kritis, bawang merah, kalium, uji korelasi

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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