Judul: Evaluasi Kesuburan Andisol pada Beberapa Kabupaten di Sumatera Utara
Abstrak: Kabupaten Humbang Hasundutan, Dairi, dan Karo merupakan daerah dataran tinggi yang berpotensi untuk pengembangan hortikultura. Akan tetapi, tingkat kesuburan tanah menjadi permasalahan utama. Penelitian bertujuan mengevaluasi tingkat kesuburan tanah serta membandingkan Andisol di Humbang Hasundutan, Dairi, dan Karo. Contoh tanah pada kedalaman 0-20cm di setiap daerah dilakukan analisis sifat kimia tanah, kemudian dilakukan perbandingan berdasarkan kriteria PPT Tahun 1995. Hasil penelitian menunjukkan terdapat variasi hasil akibat adanya perbedaan pengelolaan tanah serta jenis penggunaan lahan. Kabupaten Humbang Hasundutan memiliki rata-rata nilai C-organik tinggi, P total rendah, K total sangat tinggi, KTK rendah serta KB sedang. Kabupaten Dairi memiliki ratarata C-organik, P total serta K total yang sangat tinggi, serta KTK dan KB yang sedang. Kabupaten Karo memiliki rata-rata C-organik yang tinggi, P total dan K total sangat tinggi, KTK sedang, serta KB yang tinggi. Berdasarkan evaluasi status kesuburan tanahnya, Kabupaten Dairi dan Karo memiliki tingkat kesuburan tanah sedang, sedangkan Kabupaten Humbang Hasundutan memiliki status kesuburan rendah., Humbang Hasundutan, Dairi, and Karo regencies are highland areas with the potential for horticultural development. However, the level of soil fertility becomes the main problem. The study aimed to evaluate soil fertility levels and compare Andisol in Humbang Hasundutan, Dairi, and Karo. Soil samples at a depth of 0-20 cm in each area were analyzed regarding the soil chemical characteristics, then a comparison was made based on the soil fertility criteria PPT 1995. The results showed that there were variations in results due to differences in soil management and types of land use. Humbang Hasundutan Regency had an average of high organic carbon (C) values, low total phosphorus (P), very high total potassium (K), low cation exchange capacity (CEC) and medium base saturation. Dairi Regency had a very high average of organic C, total P and K total, as well as moderate CEC and base saturation. Karo Regency had a high average of organic C, very high total P and total K, medium CEC, and high base saturation. Based on the evaluation of the soil fertility status, Dairi and Karo Regencies had moderate soil fertility, while Humbang Hasundutan Regency had a low fertility status.
Keyword: base saturation, cation exchange capacity, organic carbon, total potassium, total phosphorus

Judul: Analysis of Soil Fertility at Various Level of Canopy Density in KHDTK Haurbentes, Bogor District, West Java
Abstrak: Kawasan Hutan Dengan Tujuan Khusus (KHDTK) Haurbentes merupakan kawasan hutan yang dimanfaatkan secara khusus menjadi hutan penelitian di kawasan hutan produksi. Kawasan hutan ini harus tetap memperhatikan kelestarian dan kesuburan tanahnya. Tujuan dilakukan penelitian ini adalah untuk menganalisis kesuburan tanah pada berbagai kerapatan tajuk berdasarkan sifat fisik dan kimia tanah. Kerapatan tajuk diukur menggunakan alat spherical densiometer (SD). Sampel tanah diambil di tiga titik secara diagonal pada petak berukuran 20 m × 20 m berdasarkan kerapatan tajuk rendah, sedang, dan tinggi. Parameter yang digunakan untuk menentukan kesuburan tanah yaitu tekstur tanah, pH tanah, C-organik, P2O5 potensial, K2O potensial, kation yang dapat ditukar, KTK, dan kejenuhan basa. Hasil penelitian menunjukkan bahwa kondisi tanah di bawah ketiga tutupan tajuk memiliki tekstur tanah beragam dari debu hingga lempung berpasir, pH tanah masam, C-organik, P2O5, dan kation dapat ditukar yang rendah, K2O yang sedang, dan kejenuhan basa yang rendah. Adapun nilai KTK sangat tinggi pada kerapatan tajuk rendah, sedang, dan tinggi berturut-turut adalah 50,30 me/100g, 52,96 me/100g, dan 53,93 me/100g. Status kesuburan tanah yang ditemukan pada setiap kerapatan tajuk masih tergolong rendah., Special Purpose Forest Area (KHDTK) Haurbentes is a forest area that is specifically used as a research forest in a production forest area. This forest area must still pay attention to the sustainability and fertility of the soil. The purpose of this study was to analyze soil fertility at various canopy densities based on the physical and chemical properties of the soil. The canopy density was measured using a spherical densiometer (SD). Soil samples were taken at three points diagonally on a 20 m × 20 m plot based on low, medium, and high canopy densities. The parameters used to determine soil fertility were soil texture, soil pH, organic C, potential P2O5, potential K2O, exchangeable cations, CEC, and base saturation. The results showed that the soil conditions under the three canopy covers had various soil textures from silt to sandy loam, acidic soil pH, low C-organic, P2O5, and cation exchangeability, moderate K2O, and low base saturation. As for the exceptionally high CEC values at low, medium, and high crown density were 50,30 me/100g, 52,96 me/100g, and 53,93 me/100g, respectively. Soil fertility status of the soil found at each canopy density was still relatively low.
Keyword: c-organik, hutan penelitian, kerapatan tajuk, kesuburan, KTK, c-organic, CEC, crown density, fertility, research forest

Judul: Simulasi Protokol Autentikasi Pelanggan pada Voice Privacy
Abstrak: Existing design of the telephone public network is susceptible to eavesdropping on its voice stream. Consequently, any wire taper can listen to supposedly private conversation. In order to prevent such eavesdropping, we propose a protocols and its implementation for end-to-end voice privacy authenticate as a service available for interested subscribers. Our protocols consist of customer enrollment system, customer authentication system and simulation voice privacy. Protocols that we made are adaptation from Sharif and Wijekesera journal with the title Providing Voice Privacy as a Service over the Public Telephone Network. The result of the process shows how the customer enrolls and how the system process the password, how the system authenticate customer simulate voice privacy.
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