Judul: Pemberian kotoran sapi pada pertanaman jagung (Zea mays) dinamika kadar c-organik dan n-tersedia pada andisol Lembang Jawa Barat
Abstrak: Penelitian Pemberian Kotoran Sapi pada Pertanaman Jagung (Zea mays) : Dinamika Kadar karbon (C) organik dan nitrogen (N) tersedia pada Andisol Lembang Jawa Barat ini dilaksanakan dari bulan Oktober 2009 hingga Mei 2010. Penelitian di lapangan dilaksanakan di Balai Penelitian Tanaman Sayuran, Lembang, Jawa Barat, sementara analisis sifat kimia tanah dilaksanakan di Laboratorium Kimia dan Kesuburan Tanah, Departemen Ilmu Tanah dan Sumberdaya Lahan, Fakultas Pertanian Institut Pertanian Bogor. Tujuan dari penelitian ini adalah untuk mengetahui dinamika perubahan kadar C-organik dan juga kadar N-tersedia (ammonium dan nitrat) pada tanah yang diberi perlakuan kotoran sapi. Perlakuan yang diberikan adalah 0 ton ha-1 and 20 ton ha-1 kotoran sapi. Pengambilan contoh tanah dilakukan pada minggu ke-1, 2, 3, 4, 6, 8, 10, dan 14 pada daerah perakaran (rhizosfer). Hasil analisis menunjukkan bahwa terjadi perubahan kadar C-organik serta kadar ammonium (N-NH4 +) dan nitrat (N-NO3 -) pada minggu-minggu pengambilan contoh tanah baik pada petak kontrol dan petak yang diberi perlakuan kotoran sapi. Proses nitrifikasi terjadi sejak minggu pertama inkubasi. Kadar NO3 - jauh lebih besar dibandingkan dengan kadar NH4 + pada setiap periode pengambilan contoh tanah. Kadar N-NO3 - mulai terlihat naik sejak minggu ke-3 inkubasi, diikuti dengan menurunnya kadar N-NH4 +. N-tersedia adalah Total dari N-NH4 + dan N-NO3 -. Data N-tersedia pada petak kontrol dan petak kotoran sapi disimulasi dengan menggunakan persamaan first order kinetic yaitu N=Nm (1-exp(-kt)), dengan N adalah konsentrasi Ntersedia, Nm adalah nilai N yang berpotensi termineralisasi, k adalah konstanta kecepatan mineralisasi, dan t adalah waktu dalam minggu. Persamaan first order kinetic untuk petak kontrol adalah N=560 (1-exp-0.242t) dengan nilai R2 sebesar 0.51 dan untuk petak kotoran sapi adalah N=717 (1-exp-0.223t) dengan R2 0.72. Berdasarkan nilai Nm dapat dilihat bahwa N yang berpotensi termineralisasi pada perlakuan kotoran sapi lebih tinggi dibandingkan petak kontrol, tetapi konstanta kecepatan mineralisasi N pada petak kontrol lebih cepat dibandingkan dengan petak yang diberi perlakuan kotoran sapi. Nilai R2 yang tinggi (0.5-1.0) menunjukkan bahwa persamaan-persamaan ini dapat digunakan untuk memprediksi laju N-tersedia pada minggu ke-t pada tanah Andisol Lembang. Dengan persamaan ini dapat dihitung bahwa N yang dapat termineralisasi akan habis pada minggu ke-30 setelah tanam
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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: Algorithm construction of HLI hash function
Abstrak: Cryptography is a study of mathematical techniques related to aspects of information security regarding on confidentiality, data integrity, entity authentication, and data origin authentication. Data integrity is a service, which is associated with the conversion of data carried out by unauthorized parties. To maintain data integrity, one can use hash functions. An hash function is a computationally efficient function to map an arbitrary length bitstring to a fixed length bitstring called as hash value. The use of hash function in maintaining the information integrity and authentication is in digital signatures, virus protection, and software distribution. Illustration of the hash function in the integrity and authentication of information that is emailed as follow. The sender sends the information and hash value to the recipient. If the hash value of the information is equal to the hash value that is sent by the sender, then information has not been changed. Otherwise the information has been changed. An hash function has two properties, one way and collision resistance. An hash function is called one way if it is computationally infeasible to find any input such that when given any hash value . Meanwhile an hash function is called collision resistant if it is computationally infeasible to find any two inputs where such that . The purpose of this study is to construct a HLI hash function algorithm, to analyze the speed and security of the hash functions as a results of construction. Furthermore, it is to compare it with SWIFFT. Hash function is constructed based on the result of algebraic operations on modular polynomial ringwith . Modular polynomial ring noted as is a set of all polynomials of degree at most with coefficients in . can be represented as a set of integer vector of modulo in dimension . So, it is simple to implement in a computer. In vector operations, is lattice . Furthermore, alattice that is defined from certain polynomial ring is called ideal lattice. HLI hash function is consists of addition and multiplication algorithm in the ring. Addition algorithm consists of sumation operations of modulo and multiplication consists of multiplication operations of modulo . Generally, algorithm of HLI hash function consists of multiplication operations of modulo and addition operations of modulo . However, if the input is binary number then multiplication algorithm only consists of multiplication operation of modulo , so algorithm of HLI hash function consists of multiplication operations of modulo and addtion operations of modulo . An hash function is secured if it has two properties, i.e., one way and collision resistance. HLI hash function hash is one way, it is following the proof of Micciancio. It is has collision resistant because of polynomial is irreducible over and monic. Moreover, it is proved that for every unit vector , the vector is small vector. If the input of hash function is a binary number then HLI hash function only involves addition operations of modulo . So the time that used almost same with SWIFFT. The excellence of HLI hash function is the key size smaller than SWIFFT. This effect on
Keyword: hash function, modular polynomial ring, lattice