Judul: Pengaruh Kedalaman Muka Air Tanah dan Dosis Terak Baja terhadap Hidrofobisitas Tanah Gambut, Emisi Karbon, dan Produksi Kelapa Sawit
Abstrak: Development of oil palm plantation requires drainage to support growth and production of the oil palm. The excessive drainage would cause the peat dryness of as well as hydrophobicity and thus decreasing its capacity to retent water, soil infiltration, surface erossion. It can limit oil palm growth. The application of water management and soil amandment must be performed to avoid the decrease of peat soil quality and to improve the productivity of oil palm. This series research was designed to: 1) evaluate the peat soil hydrophobicity under oil palm plantation area, 2) study the effect of the ground water level depth and stell slag dose on the peat soil hydrophobicity and other soil physical changes, 3) study the effect of the ground water level depth and the steel slag dose on CO2 emission from peat soil, and 4) study the effect of ground water level depth and steel slag dose on the growth and production of oil palm. The first study has utilized sapric and hemic peat soil samples taken from the 6-year Panai Jaya Oil Palm Plantation (PAJ) and the 20-year Meranti Paham Oil Palm Plantation (MEP). Peat soil samples were heated at a temperature of 50°C with a time interval and the effects on hydrophobicity were recorded. Hydrophobicity of the peat soil was evaluated by Water Drop Penetration Time (WDPT) method. After the hydrophobicity of all peat soil samples had been observed, a number of soil properties, including soil water content (SWC), total acidity, carboxylic content (COOH) and phenolic-OH were then analyzed. Critical water content (CWC) of the peat soil. The point at which hydrophobicity occurred, was determined using exponential relationship between soil water content and the probability of the occurrence of soil hydrophobicity, the point at which the probability of the occurrence of hydrophobicity was between 60% and 80%. Fourier Transform Infra Red (FTIR) spectrometer was used to evaluate peat soil hydrophobicity by knowing the functional groups in peat soil. The second experiment was carried out in laboratory by application of various steel slag level (0; 7.17; 14.81; dan 22.44 g pot-1) on two peat type (sapric dan hemic) with two soil moisture conditions including wet and dry (hydrophobic). Peat soil samples that has been added with steel slag incubation for 60 days and observation of soil properties, FTIR analysis, and wettability by WDPT method. The field experiment was carried out in 6 years-oil palm block of PAJ. Research plots was designed using a split plot design with three replications. Plots treated with three treatments of ground water level (MAT-1, MAT-2, and MAT-3) as main plots and four level of steel slag application (0; 3.15; 6.51; 9.86 kg pohon-1) as a subplot. MAT-1 is ground water level (GWL) at depths of 30-50 cm, MAT-2 is GWL at depths of 60-75 cm, and WLM-3 is GWL at depths 70-90 cm below the soil surface. The research observation consists actual soil water content, actual v hydrophobicity, oil palm growth and production, subsidence, and accumulation of heavy metals in fruit. The results shown that hydrophobicity of peat soil in this study was
Keyword: CO2 emission, hydrophobicity, oil palm, peat soil, steel slag

Judul: Pengaruh Kedalaman Muka Air Tanah dan Dosis Terak Baja terhadap Hidrofobisitas Tanah Gambut, Emisi Karbon, dan Produksi Kelapa Sawit
Abstrak: Pengembangan kelapa sawit pada lahan gambut mensyaratkan drainase tanah untuk dengan membuat saluran-saluran guna menurunkan muka air tanah dan menciptakan ruang perakaran yang sesuai untuk pertumbuhan dan produksi tanaman. Drainase yang berlebihan menyebabkan terjadinya kekeringan tanah gambut dan menyebabkan terjadinya hidrofobisitas, sehingga gambut mengalami penurunan dalam kemampuan memegang air, infiltrasi tanah, erosi permukaan, dan membatasi pertumbuhan tanaman yang diusahakan di atasnya. Penelitian ini disusun dalam suatu rangkaian percobaan dengan tujuan untuk: 1) mengkaji hidrofobisitas tanah gambut dari lingkungan perkebunan kelapa sawit, 2) mengkaji pengaruh kedalaman muka air tanah dan dosis amelioran terhadap hidrofobisitas tanah gambut dan perubahan sifat fisik lainnya, 3) mengkaji pengaruh kedalaman muka air tanah dan dosis terak baja terhadap emisi karbon dari tanah gambut, dan 4) mengkaji pengaruh kedalaman muka air tanah dan dosis terak baja terhadap pertumbuhan dan produksi kelapa sawit. Penelitian tahap pertama menggunakan tanah gambut saprik dan hemik dari kebun Panai Jaya (PAJ) yang berumur 6 tahun dan tanah gambut dari kebun Meranti Paham (MEP) yang berumur > 20 tahun. Sampel tanah gambut terlebih dahulu dipanaskan pada suhu 50o C dengan berbagai interval waktu pemanasan, kemudian diamati hidrofobisitasnya dengan metode Water Drop Penetration Time (WDPT). Analsis sifat-sifat tanah meliputi kadar air tanah, kemasaman total, kadar COOH, dan fenolat-OH. Penentuan kadar air kritis (KAK) menggunakan model hubungan eksponensial antara hidrofobisitas dan kadar air tanah (KAT) pada peluang kejadian 60-80%. Fourier Transform Infra Red (FTIR) digunakan untuk evaluasi hidrofobisitas dengan mengetahui keberadaan gugus-gugus fungsional dalam tanah gambut. Penelitian tahap kedua di laboratorium dengan aplikasi dosis terak baja (0; 7.17; 14.81; dan 22.44 g pot-1) pada dua jenis tanah gambut (saprik dan hemik) dan dua kelembaban tanah yaitu kapasitas lapangan dan kering (hidrofobik). Setelah diinkubasi selama 60 hari, sampel diamati sifat-sifatnya dan wettability dengan metode WDPT dan FTIR. Penelitian di lapangan dilakukan di blok tanaman kelapa sawit umur 6 tahun di kebun PAJ dengan perlakuan terdiri dari tiga kedalaman muka air tanah (MAT) dan empat dosis terak baja (0; 3.15; 6.51; 9.86 kg pohon-1). Kedalaman muka air tanah (MAT) terdiri dari MAT-1 (30-50 cm), MAT-2 (45-70 cm), dan MAT-3 (70-90 cm). Penelitian disusun dalam rancangan acak kelompok petak terpisah dengan kedalaman muka air tanah sebagai petak utama dan dosis terak baja sebagai anak petak. Pengamatan meliputi kadar air tanah aktual, hidrofobisitas aktual, emisi CO2, pertumbuhan, produksi kelapa sawit, subsiden, dan kadar logam berat dalam buah. Hasil penelitian menunjukkan bahwa hidrofobisitas tanah gambut dalam penelitian ini berhubungan negatif (eksponensial) dengan kadar air tanah, iii kemasaman total, kadar karboksilat, dan OH-fenolat. Penurunan kadar air tanah, kemasaman total, kadar karboksilat, dan kadar OH-fenolat akan meningkatkan hidrofobisitas tanah gambut. Penurunan kadar air tanah menyebabkan peningkatan rasio komponen hidrofobik terhadap komponen hidrofilik, dan tanah gambut mengalami hidrofobisitas. Kadar air kritis (KAK) untuk terjadinya hidrofobisitas tanah gambut dari lokasi penelitian yang diperoleh adalah 201 – 223%, 293 – 307%, 118 -126%, dan 184 – 213%, berturut-turut untuk PAJ hemik > PAJ saprik > MEP hemik > MEP saprik. Tanah gambut hemik akan mengalami hidrofobisitas lebih cepat daripada jenis saprik. Tanah gambut PAJ membutuhkan kadar air yang lebih tinggi dibandingkan tanah gambut MEP agar tanah gambut
Keyword: emisi CO2, hidrofobisitas, kelapa sawit, tanah gambut, terak baja

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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