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: Pemberian kotoran sapi pada pertanaman jagung (Zea mays) perubahan beberapa sifat kimia dan fraksi fosfor inorganik pada ultisol Gunung Sindur
Abstrak: Indonesia has wide area for acid upland soils. This upland soils are potential to develop as agricultural land. Soil order which dominantly occupied these acid upland is Ultisols. The Ultisols occupied about 24.3 % of the total acid upland soils. Acid upland soils in Indonesia have some limiting factors chemically and physically. Chemically, they have very low nutrient status and deficient in phosphorus (P), so that P fertilizer is recommended. Application of organic matter such as cow dung was expected to improve some chemical properties and P availability on acid upland soils. This reasearch was conducted in acid upland soil situated at Gunung Sindur District, Bogor Regency Cibadung Village. Analyses of soil chemical properties and the P inorganic fractions were held in the Laboratory of Chemistry and Soil Fertility, Department of Soil Science and Land Resource, Faculty of Agriculture, Bogor Agricultural University. The objectives of this research were to evaluate the effect of cow dung on the changes of some chemical properties and inorganic phosphorus fractions under maize cultivation. The rates of cow dung applied were 0, 10, 20, and 40 tons ha-1. The soil samples used were collected at the time before planting as initial soil properties, two weeks after incubation of manure application and harvest time in the rhizosphere area and between the plant rows The Application of cow dung increased soil pH significantly on two weeks after incubation and after harvest in rhizosphere area. These increases soil pH were followed by the decreases of exchangeable Aluminum. The Application of cow dung increased cation exchange capacity (CEC) significantly on two weeks after incubation but not significantly on that of after harvest in rhizosphere area and between plant rows as well. The application of cow dung increased soil organic carbon (C) on two weeks after incubation and on after harvest in rhizosphere area. The application of cow dung increased base saturation of the soil on two weeks after incubation and after harvest in rhizosphere area and between plant rows as well. The Application of cow dung increased resin-Pi and NaHCO3-Pi fractions on two weeks after incubation and on after harvest in the rhizosphere area and between plant rows as well. As for NaOH-Pi fraction, the application of cow dung only increased this P fraction on two weeks after incubation. Analyses of the P fraction changes (the content of the P fraction after harvest - two weeks after incubation) showed that the resin-Pi was negative values both in rhizosphere and between planting rows. This suggested the resin-Pi contents partly were transformed into other P fraction. The changes NaHCO3-Pi after harvest in rhiszosphere area and between plant rows were positive values. It suggested that partly resin-Pi contents were transformed into this fraction. From the evaluation of the changes on NaOH-Pi fraction which were interpreted as Al-P and Fe-P, the 3 contents of this P fraction of some samples decreased. This suggested that the NaOH-Pi fraction was not stable because it transformed to replenish if available P in soil solution depleted. Dynamics of P fractions that occurred after harvest were related to plant activities.
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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