Judul: Karakteristik Gambut Pedalaman, Transisi dan Pantai di Provinsi Riau: Keterkaitan Tingkat Dekomposisi dan Sifat Kimia Gambut dengan Produktivitas Biomassa Kelapa Sawit
Abstrak: Increased demand for palm oil derivative products (CPO, crude palm oil) causes the ever faster rate of and widespread land clearing for oil palm plantation area. Land clearing for this purpose is generally perfomed on peat swamps. In Riau Province, until year 2007, the use of peatlands for cultivating various plantation crop commodities have reached ±817.593 ha. Since peatlands are considered vulnerable to land clearing, this activity and its subsequent land management should be based on the nature and characteristics of the peat material which is largely determined by its formation physiography. Based on this background, this study aims to assess the relationship between the degree of decomposition and chemical properties of peatlands developed on fresh-water, brackish and marine physiography with biomass productivity of cultivated oil palm with age of <6 and >6 years in Riau Province. Field observations and sampling of the peat materials were conducted in January 2010. The results showed that the peat materials of Riau that developed on freshwater, brackish and marine physiography were at hemic decomposition degree. Based on the relationship between the degree of decomposition and the value of E400/E600 ratio, peat materials of the fresh-water, brackish and marine physiography cultivated for oil palm with age of >6 years were dominated by oldhemic decomposition degree (E400/E600 <5,0). Whilst, it was found in the brackish physiography with oil palm of age of <6 years peat materials with hemic decomposition degree (E400/E600 >5,0). This suggests that the degree of humification of the peat materials on oil palm cultivating lands with age of <6 years were lower than those with age of >6 years. The average organic-C content of the inland and transition peatlands were higher than those of the coastal one. The acidity was in moderate to high level in which the higher average values of pH-H2O and pH-KCl were found in transition and coastal peatlands. The average concentration of total N, P2O5 and K2O were also higher in the transition and coastal peatlands. The highest total biomass productivity of oil palm was found in the transition peatlands, both at the age of <6 and >6 years. The results of this study provides additional scientific facts that as compared to the coastal and inland ones, the transition peatlands provide as the best medium for the cultivation of oil palm, especially in Riau Province.
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Judul: Variability of Some Physical and Chemical Properties of Peat  Based on Distance from River and Peat Depth
Abstrak: Pemanfaatan lahan gambut menjadi lahan pertanian harus dilakukan dengan baik dan bijaksana. Hal ini disebabkan banyaknya faktor penghambat yang dimiliki oleh lahan gambut seperti produktivitas lahan yang semakin rendah seiring dengan bertambahnya ketebalan gambut dan rendahnya kesuburan alami tanah. Sifat fisik dan kimia gambut sangat penting untuk pengelolaan produktivitas tanaman dalam kaitannya dengan jarak dari sungai dan kedalaman pengambilan contoh. Penelitian ini bertujuan untuk mempelajari hubungan antara sifat fisik dan kimia gambut di perkebunan kelapa sawit di Kabupaten Labuhanbatu, Provinsi Sumatera Utara berdasarkan jarak dari sungai dan kedalaman. Pengambilan contoh gambut dilakukan pada transek hidrosekuen dari Sungai Leidong sebanyak 10 titik contoh. Setiap titik berjarak sekitar 300 m dari titik lainnya dan pada setiap titik diambil contoh gambut pada kedalaman 0-50 cm dan 50-100 cm. Analisis bobot isi, porositas, pH, C-organik, KTK, N-total, P-tersedia, P-total dilakukan pada setiap contoh. Perbedaan jarak dari sungai tidak berpengaruh pada bobot isi dan porositas gambut. Sebaliknya, contoh yang lebih dalam nyata memiliki bobot isi yang lebih rendah dan porositas yang lebih tinggi. Jarak yang jauh dari sungai nyata memiliki pH yang lebih rendah. Jarak dari sungai dan kedalaman contoh tidak mempengaruhi C-organik, KTK, N-total, P-total, dan P-tersedia gambut. Studi ini menunjukkan bahwa perlu dilakukan penelitian lebih detil untuk mengetahui pengaruh jarak dari sungai, kedalaman gambut dan pengaruh antropogenik terhadap pengelolaan produktivitas gambut., The utilization of peatlands for agriculture must be coducted properly and wisely. This is due to the many inhibiting factors possessed by peatlands such as lower land productivity along with increasing peat thickness and low natural fertility of the soil. The study of peat physical and chemical properties are very important for management of plant productivity in relation with the distance from the rivers and depth of samples. This study was aimed to examine the relationship between physical and chemical properties of peat in oil palm plantation in Labuhanbatu Regency, North Sumatra Province based on the distance from the river and the depth of sampling. Ten peat sampling points were carried out according to hydro sequence transect from the Leidong River. Each point was about 300 m apart from one another, and at each point peat samples were taken at depths of 0-50 cm and 50-100 cm. Analysis of bulk density, porosity, pH, organik-C, CEC, total-N, total-P, available-P was carried out on each sample. The difference of the distance from the river had no effect on the peat bulk density and porosity. On the other hand, deeper samples had lower bulk density and higher porosity. More distance from the river had lower pH. The distance from the river and depth of samples did not affect peat organik-C, CEC, total-N, total-P, and available-P. This study showed that a more detailed research is needed to determine the effect of distance from river, peat depth, and anthropogenic affect on peat productivity.
Keyword: bulk density, hydrosequence transect, oil palm, pH, porosity

Judul: Analisis kestabilan model infeksi virus leukemia feline
Abstrak: Virus leukemia foline adalah virus penyebab kanker darah dan kerusakan swnsum tulang pada kucing. Virus ini menyebar secara pidemi melalui air liur dan lendir hidung lewat interaksi antarkucing. Penyebaran virus leukemia feline ini digarnbarkan dengan suatu model matematis yang memuat sejumlah persarnaan diferensial biasa non linear yang didasarkan pada prinsip-prinsip epidemi standar (Murray, 1989). Model ini mendeskripsikan penyebaran virus lellkelllia feline dalarn suatu populasi konstan yang dihubungkan dengan waktu.
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