Judul: Pengaruh penggunaan mulsa jagung terhadap sifat fisik dan biologi tanah serta produksi jagung pada tanah latosol Cimanggu Bogor
Abstrak: Continuous cropping for food crop can reduce soil quality of agriculture land, and in turn, land productivity particularly when the farmers do not apply adequate soil and water conservation techniques. One of the soil conservation techniques that can maintain soil quality and improve quality of degraded land is the using of crop residues as mulch. The purpose of this research was to study the effect of crop residue mulch on soil physical properties particularly bulk density and porosity; soil biological properties especially the amount of soil macro fauna; and plant growth and total production of maize. This research consisted of field experiments and soil analysis. Field experiments were carried out in Latosol Cimanggu Bogor and soil analysis were conducted at the Laboratory of Physics and Soil and Water Conservation, Department of Soil Science and Land Resources, Faculty of Agriculture, Bogor Agricultural University. The study was conducted from August to December 2009. Field experiments were arranged in a completely randomized design with four doses of corn straw mulch treatments, i.e without mulch (M0), 1 ton/ha (M1), 2 tons/ha (M2), and 3 tons/ha (M3). Each treatment was repeated 3 times to make 12 units of experiments. Parameters that were observed in this study consisted of bulk density, porosity, total soil macro fauna, and plant growth and yield of maize. The results of this research showed that corn straw mulch applications up to 3 tons/ha had no significant effect on the soil physical properties particularly porosity, bulk density, available water pore, and soil porosity. However, the applications of corn straw mulch with a minimum dose of 3 tons/ha significantly increased the amount of soil macro fauna particularly ants, worms, and termites. The using of corn straw mulch up to 3 tons/ha had no significant effect on plant growth and maize production, however there was a trend of increasing production with the increasing doses of mulch applications.
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Judul: Pengaruh Pemberian Mulsa Jerami Jagung dan Kepadatan Tanah terhadap Pertumbuhan dan Produksi Jagung (Zea mays)
Abstrak: Intensive land cultivation can damage soil structure and further enable soil to be compact, and reduce water availability in the soil. Mulch application to cover the soil surface will reduce evaporation rate and increase availability of water in the soil. The research was aimed to study the effect of corn straw mulching and soil density application on physical characteristics of the soil, to determining soil bulk density and dose of mulch which is most suitable for corn growth and production of corn. The experiment was designed using a completely randomized factorial design. The first factor is the density of soil which is consist of soil bulk density 0.8, 1.0, dan 1.2 g/cm3 (K1, K2, dan K3). The second factor was corn straw mulch application which was divided into three doses i.e. 0%, 30%, 60%, and 90% (M0, M1, M2, and M3). Data were analyzed using analysis of variance (ANOVA) and further testing using Tukey Test at the level of 5%. The results of the research show the interaction of soil compaction with mulch were significantly affect on plant height at age 11-14 weeks after growing, the number of leaves at the age of 10, 11, 12, and 14 weeks after growing, dry weight of corncob both with and without husk, and dry weight of seed.The increasing of soil compaction were significantly affect on field capacity, soil resistance before planting, both total and reproductive phase evapotranspiration in single growing season, weight of roots, plant biomass, plant growth and production, also soil physics characteristic after harvest. Mulch application significantly affect on evapotranspiration of vegetative phase, plant height at 8-14 weeks after growing, stem diameter at 10 weeks after growing, and production except dry weight of seed. Soil bulk density and mulch cover suitable for the growth and production of corn is 0.8 g/cm3 and 90%.
Keyword: soil compaction, mulch, field capacity, corn growth and production

Judul: Kombinasi algoritma sha 1 dan algoritma rsa untuk membentuk tanda tangan digital
Abstrak: Tanda tangan digital termasuk ke dalam teknik kriptografi yang memanfaatkan teknologi kunci publik (enkripsi asimetris). Tanda tangan digital dapat dibuat dengan mengkombinasikan teknik hashing (untuk membentuk message digest dari pesan asli) dan enkripsi asimetris (untuk membentuk kunci publik dan kunci privat). Teknik hashing yang digunakan adalah teknik rashing satu arah dengan menggunakan algoritma SHA 1, sedangkan algoritma RSA digunakan untuk enkripsi asimetris Tulisan ini bertujuan untuk mempelajari, menganalisis, dan mengimplementasikan pembentukan dan verifikasi tanda tangan digital menggunakan dua metode, yaitu dengan mengkombinasikan algoritma SHA 1 dan algoritma RSA dan dengan menggunakan algoritma RSA saja. Analisis yang dilakukan pada kedua algoritma ini meliputi analisis algoritma, dan analisis hasil implementasi. Analisis terhadap algoritma SHA | menunjukkan bahwa algoritma ini memiliki kompleksitas O(n) untuk kasus terburuk. Sedangkan untuk pembentukan kunci publik dan kunci privat dengan algoritma RSA diperlukan beberapa algoritma pendukung, yaitu algoritma Miller Rabin, Witness, Euclid, dan Extended Euclid. Semua algoritma pendukung tersebut memiliki kompleksitas waktu yang sama, yaitu O(k), dengan adalah panjang representasi bit bilangan bulat. Kompleksitas waktu yang didapatkan untuk proses pembentukan tanda tangan digital dengan kedua metode ini adalah sama yaitu O(nk). Untuk proses verifikasi, kompleksitas waktu yang didapatkan dengan menggunakan kombinasi dua algoritma adalah O(1 + k) dan untuk algoritma RSA adalah O(n + k). Pada proses pembentukan tanda tangan digital menggunakan kombinasi dua algoritma yang ditandatangani adalah message digest yang dihasilkan oleh algoritma SHA 1, sedangkan pada algoritma RSA yang ditandatangani adalah pesan itu sendiri. Dari hasil implementasi didapatkan untuk proses pembentukan tanda tangan digital menggunakan kombinasi dua algoritma lebih cepat dibandingkan dengan menggunakan algoritma RSA saja untuk file-file yang berukuran besar, dst
Keyword: Tnda Tangan Digital, Teknik Kriptografi, Enskripsi Asimetris