Judul: Pengaruh pemberian bahan organik in situ terhadap beberapa sifat kimia tanah di lahan bekas tambang pasir besi di Kabupaten Purworejo Provinsi Jawa Tengah
Abstrak: The iron sand post mining land in the sub-District Grabag, Purworejo District is a critical land that is relatively difficult to be reclaimed. This is due to physical and chemical characteristic of soil that is unappropriate for plant growth. Physically, the post mining land is dominated by sand texture The purpose of this research were to increase the levels of soil organic matter in the sandy soil through the planting of velvet bean (Mucuna pruriens), elephant grass (Pennisetum purpureum Schumach), winged-slack flemingia (Flemingia congesta) and red calliandra (Calliandra calothyrsus) and to analyze the level of soil fertility after the biomass of treatment. The research was tested on experimental plots each measuring 240 m². The treatment plant on each plot were: (1) elephant grass, (2) velvet bean, (3) a combination of elephant grass and Flemingia, (4) a combination of elephant grass and red calliandra, (5) a combination of velvet bean and Flemingia, and (6) a combination of velvet bean and red calliandra. Basic fertilizer were urea, SP-36, KCl and humic compounds. Overall the research area was reaching 4620 m, which makes soils very porous. The sand texture and low organic matter greatly affect the low availability of nutrients. This iron sand reclamation research is conducted by providing in situ organic material with plants that are able to produce high biomass such as legumes, grass, etc. 2 The results showed that the addition of in situ organic materials were able to improve significantly the soil chemical characteristics at the iron sand post mining land. This was seen especially in the parameters of C-organic, N-total, the C/N ratio and CEC which were increased significantly. But these increase in soil chemical characteristics have not been able to improve the soil fertility class of assessment criteria from very low to low within six weeks. . When harvesting, the biomass produced by the plants were cut and then buried under the ground as deep as ± 20 cm and were left for six weeks. The addition of in situ organic materials within six weeks period can not improve the soil chemical characteristics into productive land of agriculture. It was expected with the sustainable addition of in situ organic materials can restore the condition of the land as good as before mining activities
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Judul: Reklamasi lahan bekas tambang pasir besi dengan aplikasi bahan organik in situ serta penambahan bahan humat dan kapur pada tanaman kacang tanah (Arachis hypogaea l), studi kasus PT. Aneka Tambang, Kecamatan Kutoarjo, Kabupaten Purworejo, Jawa Tengah
Abstrak: Mining activity is an effort that cannot be separated from the modern civilization. The activity of iron sand mining made that area degraded in soil physical and chemical properties. The research was conducted in iron sand post mining area of PT. Aneka Tambang (ANTAM), at Patutrejo, Grabag Village, Kutoarjo, Central Java from March 2010 until July 2010. Reclamation efforts had been conducted by PT. ANTAM by giving compost to the soil and then planting perenial plants namely Ketapang tree. That compost was imported from others area. This became an obstacle because compost in the surrounding area was very limited. Therefore using organic matter in situ, was a simple and easy way. In situ biomass production needed to be developed to improve soil fertility of iron sand post mining area. Therefore, it was needed plants that were tolerant to soil physical properties in ex-mining area, as well as producing organic matter in situ. The plant that have been used often as organic matter source in situ was legume crops. Legume crops can produce more organic matter, high in nutrient uptake and have nodules that can fixed nitrogen from atmosphere. Legume crop that was used in this research was peanut (Arachis hypogaea L). Planting peanut in iron sand mining area may improve soil properties through nitrogen (N2) fixation.
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Judul: Approximation of the Median of Poisson Distribution Using the Relation of Poisson-Gamma Distribution
Abstrak: A major drawback of median is that median cannot usually be defined in closed form, even in the cases where their distribution functions are known. This study gives an approximation of the closed form for the median of the Poisson distribution by using the relation of Poisson-Gamma distribution. The approximation uses elementary techniques based on the monotonicity of certain sequences involving tail probabilities of the Poisson distribution and the Central Limit Theorem. Furthermore, a closed form expression for the mean absolute deviation 􀜧|􀜰􀰒 􀵆 􀜯􀝁􀝀􁈺􀜰􀰒􁈻| is also studied. The median is relevant because of the fact that it minimizes the mean absolute deviation of a Poisson random variable (􀜰􀰒􁈻 by considering median as central tendency.
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