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: 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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