Judul: Estimasi nilai ekonomi lingkungan perkebunan kelapa sawit ditinjau dari neraca air tanaman kelapa sawit: studi kasus perkebunan kelapa sawit di Kecamatan Dayun Kabupaten Siak Propinsi Riau
Abstrak: Dayun is one of the center of oil palm plantations in Siak. Government company that develops the oil palm plantation in Dayun is PT. Perkebunan Nusantara Lima (PTPN V) and also the first company which develops the oil palm in Siak. The oil palm plantations cause various effects to the environment; one of them is the decreasing of water availability that can be used by the water stakeholders. The decreasing of water availability causes additional cost to the community. The objectives of this study are to determine the decreasing of water because of the oil palm plantation and cost that spent to meet the needs of water. The study uses water balance model by Thornwhite 1957 and Willingness to Pays (WTP) analysis using questionnaire of Contingent Valuation Method (CVM) in Sawit Permai, Dayun, Siak.The land cover, before and after, affect the water balance which impact the water availability in Dayun. The decreasing of water availability is comparable with the increasing of water demand in oil palm plantation, equal to 67 mm/year. Oil palm plantation has greater runoff than forest. The need of water in oil palm plantation in Dayun is 42.728 liters /ha /day, with the need of a single palm tree equal to 0,012 m3/s/day. Based on the analysis of debt estimation, there is debt decreasing which indicates the decreasing of water availability in Dayun, around 349 m3/s/year. The estimated value of the environment for oil palm plantations by water resources consumption based on the difference of forest and oil palm plantations during the dry season (JJA) is equal to Rp 7.500.000.. Average WTP for the water conservation program is Rp 26.400, with WTP maximum and minimum up to Rp 45.000 and Rp 5.000 respectively. The economic value of water conservation program is Rp 18.850.000/month.
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Judul: Perception and Income of Farmer’s towards Alternative Oil Palm Replanting Elective in Dayun District Siak Regency
Abstrak: Kecamatan Dayun merupakan salah satu daerah potensial untuk perkebunan kelapa sawit yang ada di Kabupaten Siak, Provinsi Riau. Luas perkebunan kelapa sawit di Kecamatan Dayun adalah 24.972 hektar. Perkebunan kelapa sawit di Dayun dimulai sejak tahun 1987, dengan umur tanam tersebut maka usahatani kelapa sawit di Dayun perlu untuk dilakukan peremajaan (replanting). Penelitian ini bertujuan untuk (1) Menganalisis persepsi petani terhadap upaya peremajaan kelapa sawit di Kecamatan Dayun Kabupaten Siak (2) Menghitung tingkat pendapatan usahatani kelapa sawit di Kecamatan Dayun Kabupaten Siak (3) Mengidentifikasi alternatif sistem peremajaan kelapa sawit yang tepat untuk petani di Kecamatan Dayun Kabupaten Siak. Penelitian ini menggunakan analisis deskriptif untuk mengetahui persepsi petani dengan metode Skala Likert, analisis pendapatan untuk mengetahui tingkat pendapatan petani kelapa sawit, dan analisis kelayakan usaha untuk mengidentifikasi pola peremajaan yang tepat di Kecamatan Dayun. Hasil penelitian menunjukkan persepsi petani terhadap upaya peremajaan dilihat dari enam aspek peremajaan adalah baik. Rata-rata pendapatan atas biaya total yang diperoleh petani dari usaha tani kelapa sawit yaitu sebesar Rp1.959.741,85/ha/bln. Pola peremajaan tumpang sari tepat dijadikan solusi bagi petani di Kecamatan Dayun agar dapat terus memperoleh pemasukan selama masa peremajaan karena layak secara finansial dan memiliki waktu pengembalian modal lebih cepat dibandingkan dengan pola peremajaan konvensional., Dayun District is one of the potential regions for oil palm manors in Siak Regency, Riau Province. The space of oil palm manors in Dayun District is 24,972 hectares. Oil palm manors in Dayun District began in 1987, with the planting age, oil palm cultivating in Dayun District should be replanted. This study plans to (1) analyze farmer’s perceptions of oil replanting in Dayun District, Siak Regency (2) Calculate the farmer’s income from oil palm in Dayun District, Siak Regency (3) Identify elective oil palm replanting that are proper for farmer’s in Dayun District, Siak Regency. This study uses a Likert Scale to see farmer’s perceptions of oil palm replanting, income analysis to calculate oil palm farmer’s income, and business feasibility analysis to determine the right choice of oil palm replanting in Dayun District. The results showed that farmer’s perceptions of oil palm replanting viewed from the six aspects were good. Average income obtained by farmer’s from oil palm is Rp1.959.741,85/ha/month. Intercropping replanting design is the right answer for farmer’s in Dayun District with the aim that they can still earn income during the replanting period because it’s financially achievable and has a faster payback period than conventional replanting design.
Keyword: Analisis kelayakan, peremajaan konvensional, replanting, skala Likert

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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