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: Chemical and Physical Properties of Peat Soil under Oil Palm and Shurb
Abstrak: Penggunaan lahan gambut untuk pertanian terus meningkat akibat potensi yang sangat besar dalam menyediakan kebutuhan bahan pangan. Penanaman kelapa sawit pada lahan gambut perlu mencermati sifat fisika dan kimia tanah gambut, agar menghasilkan produksi yang maksimal. Penelitian ini bertujuan mengamati sifat fisika dan kimia tanah gambut dibawah tegakan kelapa sawit dan semak belukar serta mengindentifikasi pengaruh penggunaan lahan, jarak dari kelapa sawit dan kedalaman contoh tanah terhadap sifat kimia dan fisika tanah gambut. Pengambilan contoh tanah gambut dilakukan di perkebunan kelapa sawit PT KTU (Kimia Tirta Utama) yang berada di Kabupaten Siak, Provinsi Riau. Pengambilan contoh tanah gambut dilakukan pada 10 titik pada masing-masing kedalaman di bawah tegakan kelapa sawit dengan tiga jarak dari kelapa sawit yang berbeda (1,5 m, 3 m, 4,5 m) dan 10 titik pada masing-masing kedalaman di semak belukar. Hasil sidik ragam menunjukan bahwa sifat kimia dan fisika tanah gambut pada tegakan kelapa sawit dan semak belukar berbeda nyata. Sebagian besar sifat kimia dan fisika tanah gambut akan menurun dengan bertambahnya kedalaman gambut. Analisis PCA menunjukkan bahwa sifat kimia dan fisika tanah gambut pada penggunaan lahan semak belukar menjadi faktor penentu utama keragaman data. Namun, pada penggunaan lahan kelapa sawit, sifat fisika dan kimia tanah gambut menunjukkan perbedaan kontribusi terhadap komponen utama. Pada data kedua penggunaan lahan menunjukkan bahwa sifat fisika menjadi faktor penentu utama keragaman data. Penggunaan lahan dan kedalaman memiliki perbedaan yang nyata, sedangkan jarak dari pohon kelapa sawit tidak berbeda nyata terhadap sifat fisika dan kimia tanah gambut., The use of peatland for agriculture continues to increase due to high potential in providing food needs. The cultivation of palm oil on peatland needs to be observe to the chemical and physical properties of the peatland. This is related to the management of oil palm plantations that can make maximum production. This research was aimed to observe the physical and chemical properties of the peatland under oil palm plantation and shurbs and to identify the relationship between the physical and chemical properties of peatland. Sampling was carried out at 10 sample points under oil palm plantation with three different distances from palm oil. (1,5 m, 3 m and 4,5 m) and 10 points in the shrub. Soil samples taken were disturbed and undisturbed soil samples. Each point samples were taken based three soil depths (0-20 cm, 20-40 cm and 40-60 cm). The results of variance showed that the chemical and physical properties of peat soil in oil palm stands and shrubs were significantly different. Most of the chemical and physical properties of peat soils will decrease with increasing peat depth. PCA analysis shows that chemical and physical properties of peat soils in bush land use are the main determinants of data diversity. However, in the use of oil palm land, the physical and chemical properties of peat soils show different contributions to the main components. The second data shows that the physical properties of the land use are the main determining factors for the diversity of the data. Land use and depth have significant differences, while the distance from oil palm trees is not significantly different
Keyword: management, distance from palm oil, PCA Analysis, soil depth, manajemen, jarak dari kelapa sawit, kedalaman tanah, analisis PCA

Judul: Grup dan Homomorfisma Grup pada Rubik Revenge
Abstrak: Rubik cube is a kind of puzzle game. A player must arrange rubik sides, which have been disordered, back to the position where every side has the same colour. This paper does not focus on the settlement solution, but instead on proving the existence of a group homomorphism between rubik movement group and S96 symmetric permutation group in rubik revenge. Firstly, it has been proved that rubik movement set is a group. Then, it also has been proved that the M set, which contains numeric labels of 1 until 96 in cubinos sides, is S96 symmetric permutation group.
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