Judul: Pemanfaatan bahan humat dan abu terbang untuk reklamasi lahan bekas tambang
Abstrak: Open pit coal mining activities consist of land clearing, removal and placement of top soil, removal and dumping of overburden, and coal getting. Those activities have some impact on landscape changes and degradation of soil. Therefore, reclamation of ex-mining area is needed to improve post mining land become a stable and productive land. Impact of open pit coal mining generally are decreasing of soil characteristics such as declining of soil pH, soil nutrients, and soil organic matter. Improvement of the soil can be done by application of soil amendments. One of alternatives for soil amendment that available in the field is fly ash. Having high pH and nutrients, fly ash can be used to increase soil pH and source of soil nutrients. However most of K, Na, Ca and Mg in fly ash are still bounded in oxide bonding. Humic subtances may be used for increasing of the release of nutrients in fly ash. Humic subtances have polyelectrolite macromolecules such as carboxyl and OH-fenolic that can stimulate for releasing nutrients in fly ash. The objectives of this research are studying influence of humic subtances and fly ash on plant growth, absorption of the plant, and soil chemical characteristics. This research was conducted on February to July 2009 in nursery and post mining land at Sangatta Region, PT Kaltim Prima Coal, East Kutai Regency, East Kalimantan. The experiment was conducted in two locations i.e. first experiment in nursery area using Completely Randomize Design with 2 factors; humic subtances dosages (0,00; 0,075; and 0,15 ml/polybag) and fly ash dosages (0; 200; dan 400 g/polybag). Albazia falcataria and Shorea parvifolia Dyer are use as indicator plants. Second experiment was conducted in post mining area using Group Randomize Design with 2 factors, humic subtances dosages (0,000; 0,9375; and 1,875 ml/plant) and fly ash dosages (0,0; 2,5; and 5,0 kg/measurement plot). The plants were planted in three slopes i.e. upper slope, middle slope, and foot slope. The growth and production of plants were measured. Plant analysis was also conducted to evaluate the effect of soil amendments on plant absorption. The soil analysis covers pH, organic matter, N, P-Bray I, exchangeable bases of Ca, Mg, K, Na, exchangeable Al and CEC. The results showed that humic subtances increase the CEC and organic matter of soil while fly ash increases the pH, P and exchangeable bases. Humic subtances and fly ash increase the growth of Albazia falcataria relatively quick than that of Shorea parvifolia Dyer. Humic subtances and fly ash increase the absorption of Ca and Mg by plants. There is a positive correlation between increasing soil nutrients and plant growth as well as plant absorption
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Judul: Pengaruh abu terbang dan bahan humat terhadap pertumbuhan tanaman sengon (Paraserienthes falcataria) dan sifat-sifat kimia tanah di lahan bekas tambang batubara
Abstrak: Indonesia is the largest coal producer in Southeast Asia. Some problems will appear in coal mining during and after mining especially land degradation. For reclaiming land degradation, some efforts can be done to improve the physical, chemical, and biological properties of soil. Some of the alternatives for soil ameliorant are fly ash and humic substances. Fly ash can be obtained from the coal burning at the electric power plant while humic substances can be extracted from organic materials. Application of fly ash and humic substances in the soil at ex-coal mining are expected to improve the physical, chemical and biological properties of soil. The research aims to find out the effect of fly ash and humic substances on sengon’s growth (Paraserienthes falcataria) and chemical properties of soil in the ex-coal mining land. This research was conducted in a greenhouse, nursery PT. Kaltim Prima Coal, East Kutai, East Kalimantan Province. The research used a completely randomized design factorial of two factors. The first factor were 3 levels of fly ash: 0 tons/ha, 40 tons/ha, and 80 tons/ha, or equivalent to 0 g/polybags, 200 g/polybag, and 400 g/polybag. The second factor were 3 levels of humic substances: 0 l/ha, 15 l/ha, and 30 l/ha, or equivalent to 0 ml/polybags, 0,075 ml/polybags, and 0,15 ml/polybags. Each polybag filled with soil material as much as 10 kg. Each treatment was repeated as many as 5 times. The results showed the interaction between fly ash and humic substances significantly increased the N content, N absorption, plant height, and weight of leaves. The highest result of those parameters was the treatments of F2H2. The analysis also showed that fly ash significantly increased pH, total-N, organic-C, exchangeable-K, exchangeable-Na, exchangeable-Ca, base saturation, K content, Mg content and Mg uptake of leaves, and tended to increase the available-P, P content and P uptake of leaves, and decreased the exchangeable-Al. Humic substances significantly increased the available-P and exchangeable-Ca, and tended to increase pH, C-organic, Cation Exchange Capacity (CEC), Mg uptake of leaves, and decreased the exchangeable-Al.
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Judul: Konstruksi aritmetika kurva eliptik F(2m) supersingular dan non-supersingular untuk skema kunci publik ElGamal
Abstrak: Algoritme ElGamal adalah salah satu algoritme kunci publik dengan aritmetik modular p yang mempunyai struktur grip siklik Z(p). Tingkat keanaman algoritme ini terletak pada pemecahan masalah logaritme diskret dari Z(p). Akan tetapi, tingkat keamanan tadi tahun ke tahun semakin menurun yang disebabkan kemampuan pemecahan algoritme diskret semakin meningkat. Untuk memenuhi tingkat keamanan yang memadai dibutuhkan p yang cukup besar yang menyebabkan proses enkripsi dan dekripsi menjadi lambat.
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