Judul: Pertumbuhan Bibit Krey Payung (Filicium decipiens) pada Media Bekas Tambang Pasir dengan Penambahan Arang dan Pupuk NPK
Abstrak: Mining activity is one of exploitation natural resources exploitation which is consist of land clearing activities, extraction, dredging or landfill. One type of mining that usually do by the communities is sand mining. Problems arising from mining, among others, the land vulnerable to landslides, sedimentation of sand in the river, the potential for flooding in the lower areas, the loss of soil organic matter, loss of soil layer, soil structure changes, air pollution in the form of dust, and damage to rural roads. Revegetation should become a absolute activities on ex mined land, but revegetation efforts often face a very severe constraint. In the land of the former sand mining has dominated the sand texture with low KTK and low nutrient content. Charcoal and NPK fertilizer application expected to overcome it. Krey payung has good prospects for growing trees classified in different types of soil, and produce a lot of litter for soil improvement, and has a canopy and attractive leafy. The results showed that the greatest growth is combined with charcoal without NPK fertilizer and it gave krey payung seedling growth is best shown by the IMB (seed quality index) value of 29 points. Giving largest single charcoal which is 10% to the planting medium sand mined lands provide an krey payung seedling growth is best shown by IMB value of 28 points. Treatment given media without NPK fertilizer best response krey payung seedling growth indicated by IMB value of 30 points. The addition of NPK on soil media former sand mining respond less well on seedling growth krey payung.
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Judul: Pertumbuhan Bibit Sengon (Paraserianthes falcataria (L) Nielsen) pada Media Bekas Tambang Pasir dengan Pemberian Subsoil dan Arang Batok Kelapa
Abstrak: Exploitation of natural resources in order to meet the increasingly commonplace as the needs of the population increase. Exploitation are likely to cause environmental damage. One such activity is the mining of sand. River sand mining will lead to a sustained decrease in the amount of sand in the river bed. As a result, the river will be damaged by excavation continues. In addition to damaging the ecosystem of the river, sand mining has also led to a decrease in water quality and air pollution. In order to reduce the impact of damage, utilization and processing of mining waste as a growing medium in a first step into alternative revegetation can be done. However, low nutrient content and CEC and texture of sand dominated an obstacle in the utilization of tailings sand as a growing medium. Application subsoil and the addition of coconut shell charcoal is expected to help improve these constraints. Sengon is a very fast growing plant and has a high potential and has been widely known to the public. These plants are best used in the post-mining land rehabilitation. The results showed that the addition of the interaction of subsoil and coconut shell charcoal gives the best growth of influence. Interaction addition of 75% subsoil and charcoal 40 g (a3b2) is the best treatment to improve seedling height by 64%. While the increase in diameter increment, the interaction of subsoil 75% and the addition of 60 g charcoal (a3b3) is the best treatment with the addition of a diameter of 87.50%. The best treatment for weight parameters in total bases (BKT) and total dry weight (BKT) indicated by the treatment (a3b3) with a 63.49% increase% and 36.10%. Giving a single charcoal best in show at the addition of 60 g charcoal (a0b3). Indicated by a high addition of 47.32%. While granting subsoil singly not give significant effect on seedling growth.
Keyword: sengon, subsoil, Charcoal, mining sand

Judul: Penggunaan Teorema Homeomorphy 2-Manifold dan Teorema Euler Poincare pada Torus 𝑇�� dan Simplicial Complex 𝐾��
Abstrak: Two dimensional topological spaces are said to be homeomorphic if they have the same topological invariant, where one of topological invariant used is an Euler characteristic. Homeomorphy 2-Manifold’s Theorem and Euler Poincare’s Theorem are used to distinguish two topological spaces. Homeomorphy 2-Manifold’s Theorem uses Euler characteristic to identify two dimensional topological spaces. Euler Poincare’s Theorem is an alternative way to find Euler characteristic with Betti number, which is topological invariant as well. The objective of this paper is to investigate the homeomorphism of torus 𝑇����� and simplicial complex 𝐾�����. Topological space torus and simplicial complex 𝐾����� have the same Euler characteristic, which is two. Based on Homeomorphy 2-Manifold’s Theorem topological space torus 𝑇����� and simplicial complex 𝐾����� is homeomorphic.
Keyword: simplicial, torus, Euler, homeomorphism, topology