Judul: Pemberian kotoran sapi pada pertanaman jagung (Zea mays) perubahan beberapa sifat kimia dan fraksi fosfor inorganik pada andisol Lembang, Jawa Barat
Abstrak: The research entitled Fraction The Application of Cow Dung on Maize (Zea mays) cultivation: The Changes of Some Chemical Properties and Phosphorus Inorganic Fractions on Andisol Lembang was conducted from September 2009 until April 2010. The research in the field was conducted at Indonesian Vegetables Research Institute, Lembang, West Java, while the chemical properties of soil analyses were performed at the Laboratory of Soil Chemistry and Fertility, Department of Soil Science and Land Resource, Faculty of Agriculture, Bogor Agricultural University. The background of this research is the high application of organic metter to overcome the very high P retention in this soil. Therefore the research concerning the P fractions distribution is very important. The researches related to the effect of organic matter to changes on P fractions would have been a lot done, but researches data on those for Andisol Lembang is not yet available. The objectives of this research were to evaluate the effect of cow dung to changes of some chemical properties and fractions of inorganic P (Pi) on maize cultivation in the root (rhizosfer) area and in between crop rows. The treatments were applied in four rates those were 0, 10, 20, and 40 tons ha-1 and each treatments were repeated three times. Composite soil sampling was conducted at two weeks after incubation (prior to maize planting) and after harvest when the maize was about three months collected in the rhizosfer area and in between rows of plants. The changes on P fractions were calculated by subtracting the fraction P after two weeks of incubation with fraction P after harvest in the rhiszosfer area and in between rows of plants. The results of preliminary analyses suggested that this Andisol Lembang was slightly acid. C-organic carbon was very high status, cation exchange capacity (CEC) was high status, base saturation (BS) was low status, total N was medium status, available P was high status and soil texture class was silt loam. The high available P suggested that P fertilization in Andisol Lembang was very intensive. The results suggested that cow dung did not increase significantly soil pH, soil CEC, and C-organic. The cow dung did not increase BS significantly after two weeks of incubation but increase BS significantly at harvest in the rhizosfer area and in between rows of plants. The BS values at harvest were lower than two weeks after the incubation that suggesting there was leaching process or the removal of nutrients by the plants. The cow dung increased resin-Pi significantly. The changes in resin-Pi after harvest in between rows of plants and rhizosfer area were negative in their values. Those indicated that there was a transformation process of the resin-Pi into other P fractions or absorbed by plants. The cow dung increased NaHCO3-Pi significantly at harvest in both the rhizosfer area and in between rows of plants but did not increased this fraction significantly at after two weeks of incubation. The changes of NaHCO3-Pi in the rhizosfer area were positive in their values indicating that the resin-Pi transformed into this fraction. While the values of a negative changes
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Judul: The Application of Cow Dung on Corn (Zea Mays) Cultivation: The Dynamic of Changes in Organic Carbon and Available Nitrogen Content in Ultisol Gunung Sindur.
Abstrak: The research entitled The application of Cow Dung on Corn (Zea Mays) Cultivation: The Dynamic of Changes in Organic Carbon (C) and Available Nitrogen (N) Content in Ultisol Gunung Sindur was conducted in Cibadung village, Gunung Sindur, West Java. Chemical Analyses were conducted in Laboratory of Soil Chemistry and Fertility Department of Soil Science and Land Resource, Faculty of Agriculture, Bogor Agricultural University. The objectives of this research were to evaluate the dynamic of changes in Organic C and available N (ammonium and nitrate) in Ultisol Gunung Sindur treated by cow dung on corn cultivation. The treatments were 0 ton ha-1 (control plot) and 20 ton ha-1 of cow dung in air air-dried condition. The soil samples collection were conducted at 1st, 2nd, 3th, 4th, 6th, 8th, 10th and 14th week after planting in root zone. Organic C content in plot treated by 20 ton ha-1 of cow dung increased with time of soil samples collection and their values were always higher than those of control plot up to 6th week. The equilibrium where the content of organic C of control and plot treated by 20 ton ha-1 of cow dung were similar and constant, occured at 14th week after planting. Ammonium content in plot treated by 20 ton ha-1 of cow dung increased with time of soil samples collection and their values were always higher than those of control plot up to 14th week. Similar to organic C content, the equilibrium was reached at 14th week after planting. The first order kinetic equation coud not be used to simulate the data of ammonium. The Nitrate content increased with time of soil samples collection. The nitrate contents in control plot and plot treated with 20 ton ha-1 of cow dung as well, were always higher than those of ammonium in all time of soil samples collection. The first order kinetic equation revealed that in control plot N which was potential to mineralize to be nitrate was 494 mg kg-1 with rate constant 0.61 week-1 while in plot treated with 20 ton ha-1 of cow dung, N which was potential to mineralize to be nitrate was 620 mg kg-1 with rate constant 0.41 week-1. As for availabe N (ammonium + nitrate), N which was potential to mineralize to be available N in control plot was 538 mg kg-1 with rate constant 0.63 week-1 while in plot treated with 20 ton ha-1 of cow dung N which was potential to mineralize to be available N was 665 mg kg-1 with rate constant 0.46 week-1. The first order kinetic equation also revealed that N from 20 ton ha-1 will fully mineralize to be nitrate and available N at 14th week after planting. The results suggested that equilibrium of application of 20 ton ha-1 cow dung on corn plantation in Ultisol Gunung Sindur for organic C, amonium, nitrate and available N occured at 14th week. N mineralization to be nitrate and available N was simulated well by first order kinetic equation.
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Judul: Cycle Hamilton pada Graf Lengkap, Graf Regular, dan Graf 2-Connected 4-Regular Berorder Kurang dari Sepuluh
Abstrak: Suatu graf disebut graf Hamilton apabila graf tersebut memuat cycle Hamilton, yaitu cycle yang melewati setiap vertex tepat satu kali. Menentukan keberadaan cycle Hamilton pada suatu graf dapat menggunakan syarat cukup yang berupa teorema-teorema yang telah diperkenalkan sejak tahun 1950-an. Beberapa syarat cukup yang dibahas dalam karya ilmiah ini adalah syarat cukup yang berhubungan dengan graf lengkap dan graf regular. Suatu graf lengkap berorder 𝑛������ ≥ 3 dan graf r-regular berorder 𝑛������ ≤ 2𝑟������ + 1 merupakan graf Hamilton, Karena kedua graf tersebut memuat cycle Hamilton. Selanjutnya, syarat cukup tersebut digunakan untuk menentukan keberadaan cycle Hamilton pada graf 2-connected 4- regular berorder kurang dari 10.
Keyword: graf Hamilton, graf regular, graf lengkap, graf 2-connected 4-regular