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: Produksi biomassa oleh tanaman rumput gajah, koro benguk, kaliandra dan flemingia di lahan bekas penambangan pasir besi Kecamatan Kutoarjo, Purworejo Jawa Tengah
Abstrak: Iron sand as one type of mineral is a great potency in the subdistrict of Kutoarjo, Purworejo district. However, it has been realized that mining activities can not be separated from the effects towards the surroundings environment, especially from the aspect of land degradation. Physically, the land at the site of the iron sand post mining is dominated by the sandy texture. One method of amelioration for sandy soils is by providing organic material. In this research, the organic material was supplied in situ from the elephant grass (Pennisetum purpureum Schumach), velvet bean (Mucuna pruriens), red calliandra (Calliandra calothy rsus ) and winged-slack flemingia (Flemingia congesta). The objectives of this research were to know the amount of biomass produced by each plant type and to find out the quality of plant biomass based on N, P, K absorption parameters in plants. The plants which had to be tested on each plot were: (1) elephant grass, (2) velvet bean, (3) a combination of elephant grass and winged-slack flemingia, (4) a combination of elephant grass and red calliandra, (5) a combination of velvet bean and winged-slack flemingia, and (6) a combination of velvet bean and red calliandra. Each treatment was tested in experimental plots measuring 240 m2 and were repeated three times, so there were 18 experimental plots, plus three control plots measuring 100 m2. Overall the research area was reaching 4620 m2. The results from over five months research showed that the biomass of plants with the largest amount was produced by elephant grass at the fourth plant treatment plot and also by velvet bean at the fifth plant treatment plot. The elephant grass at the fourth plot capable of producing dry matter 8.32 tons/ha in 18 weeks, while the velvet bean at the fifth plot produce dry matter 2.13 tons/ha in 18 weeks. Both of these plants had a relatively more balanced ratio of N, P and K contents and uptakes in plants. The NPK ratio of fourth plot was (0.79:0.13:1.47) and the fifth plot was (1.74:0.15:0.76). Plants that produce high biomass can provide a large amount of organic material in the post mining land which lack of organic material. In addition, the content and balanced nutrients uptake in plant biomass play a role in improving the availability of nutrients in the land.
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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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