Judul: Pyrite and weathered jarosite inactivation of  acid sulphate soil by leaching and biofilter use
Abstrak: The experiments were conducted in the Laboratory of Soil Chemistry and Fertility, Faculty of Agriculture, IPB from March to July 2009, and greenhouse of Indonesian Research Institute for Swampland Agriculture (IRISA), Banjarbaru, South Kalimantan, from October until May 2010. The study was aimed to: (1) investigate the effectiveness of leaching water sources for reducing Fe2+, total-Fe, SO4 2-, and Al3+ concentration in leachate and soil at Eh values of -100 to 400 mV, (2) study the effect of leaching water source (fresh water, brackish water, and peat water) on concentrations of Fe2+, total-Fe, and SO4 2- in leached and soil of acid sulphate soil, and (3) study the effect of leaching water source, root volume (biofilter plant area/pot) and kind of biofilter plants on reducing concentration of Fe2+, total-Fe, and SO4 2- in leached and soil. The results showed that brackish water increased concentration of Fe2+, total-Fe, and Al3+ in leachate, while peat water increased concentration of SO4 2- in leachate. The higher concentration of Fe2+ was found at Eh condition of 100 mV in leachate, while the higher concentration of total-Fe, SO4 2-, and Al3+ was found at Eh condition of 400 mV. Chemical analysis of soil after leaching for eight weeks showed that brackish water decreased concentration of Fe2+ and Al 3+ in soil, while peat water decreased concentration of total-Fe and SO4 2- in soil. Eh condition at 200-300 mV reduced lower concentration of Fe2+ in soil, while at 400 mV reduced concentration of total-Fe, SO4 2-, and Al3+ in soil. During the leaching process, the concentration of Fe2+, total-Fe, and SO4 2- in leachate were decreased. The decrease of that concentrations in the first period was greater than that in the second period. Leaching by brackish water was more effective than by fresh water or peat water in lowering the concentration of Fe2+ and total-Fe in leached. Whereas, leaching by using peat water was more effective to decrease the concentration of SO4 2- compared other treatments. Leaching water sources had no significant effect in improving growth and yield components of Margasari rice variety, but significantly increased dry weight and yield of rice. Dry weight and yield of rice were higher on soil leached by peat water and fresh water than those on soil leached by brackish water. Eliocharis dulcis showed greater ability than Eleocharis retroflaxa to decrease the concentration Fe2+, total-Fe, dan SO4 2- in leachate. Increasing root volume (biofilter plant area/pot) of biofilter plants increased the plant ability in reducing the concentration of those ions in leachate. The leaching water sources had no consistent effect on the difference of Fe2+, total-Fe, and SO4 2- concentration in leachate.
Keyword: Leaching Process, Pelindian, Biofilter, Air Insitu

Judul: Pelindian Pirit Dan Jarosit Pada Tanah Sulfat Masam  Dengan Air Gambut Pada Beberapa Nilai Eh
Abstrak: Permasalahan utama pada tanah sulfat masam adalah teroksidasinya pirit yang muncul ke permukaan dan meningkatkan kadar unsur Al, Fe dan S yang bersifat racun bagi tanaman. Dalam pertanian tradisional proses oksidasi pirit di lapangan berjalan sangat lambat dan membutuhkan waktu yang lama. Salah satu upaya untuk mempercepat terjadinya oksidasi adalah melalui pengeringan dan pencucian. Salah satu bahan pelindi yang potensial dan bermanfaat yang dijumpai di lapangan adalah air gambut. Penelitian ini bertujuan untuk mengetahui kandungan ion Fe3+, SO42- dan Al-dd pada tanah sulfat masam setelah pelindian pada tanah yang dikondisikan pada beberapa nilai Eh (-100 ±25, 0 ±25, 100 ±25, 200 ±25, 300 ±25, 400 ±25 mV) menggunakan air gambut. Penelitian ini dilakukan di laboratorium Kesuburan Tanah, Departemen Ilmu Tanah dan Sumberdaya Lahan, Fakultas Pertanian, Institut Pertanian Bogor dari bulan Maret hingga Agustus 2009. Tanah yang digunakan adalah tanah yang mengandung pirit > 2% yang diambil dari kebun percobaan Balai Penelitian Pertanian Lahan Rawa Balandean, Kabupaten Barito Kuala, Kalimantan Selatan Banjarmasin. Air gambut yang digunakan untuk melindi diambil dari km 18 Kecamatan Gambut, Kabupaten Banjar Kalimanatan Selatan. Dari hasil penelitian ini diperoleh bahwa pelindian yang telah dilakukan selama 8 minggu menggunakan air gambut menunjukkan bahwa terjadi penurunan kosentrasi Fe3+, SO42- dan Al-dd pada tanah sulfat masam yang dikondisikan pada Eh 400 ±25 mV. Ion- ion yang terdapat pada air hasil lindian yang dianalisis setiap minggunya menunjukan bahwa Eh 400 ±25 mV memiliki kosentrasi Fe3+, SO42- dan Al paling tinggi. Hasil ini menunjukkan bahwa pengaruh oksidasi dan pelindian tertinggi terdapat pada Eh 400 ±25 mV dimana merupakan nilai Eh tertinggi pada penelitian ini. Proses pelindian mampu menurunkan kosentrasi Fe3+, SO42-, dan Al-dd secara efektif pada tanah sulfat masam selama 4 minggu pelindian. Pelindian pada minggu kelima dan selanjutnya (pada penelitian ini hingga minggu kedelapan) tidak berpengaruh positif lagi terhadap redoks pada perlakuan yang diindikasi dengan menurunnya nilai Eh menjadi 150 ±25 mV. Pelindian menggunakan air gambut pada penelitian ini meningkatkan kandungan basa-basa pada tanah sulfat masam. Kata kunci : Al-dd, Eh, Fe3+, pelindian, SO42- , sulfat masam
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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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