Judul: The characteristics of paddy soils at the toposequence with volcanic parent material in Bogor – Jakarta area
Abstrak: The aims of the research were: (1) to study the characteristics and genesis of paddy soils at the toposequence with volcanic parent materials in Bogor . Jakarta area, (2) to study the influence of paddy cultivation intensity on the formation of surface gley, plow pan, Fe and Mn layer, (3) to study the movement of Fe and Mn soil, and (4) to study the mineralogy and classification of the soils. Twelve pedons, selected based on: (1) soils subgroup, and (2) cultivation intensity were investigated. Soil sample were collected from each horizon of the pedons for laboratory analysis. The result of the research shows that the morphology, the non-paddy soils consists only of tillage layer and the original soil layer. The once paddy a year soils, besides the tillage layer, show further horizonisation, including less visible plow pan layer (bulk density slightly higher than the tillage layer), Fe accumulation and Mn accumulation layer, and the original soil layer; meanwhile, the horizon of the twice a year paddy soils are as follows: more visible reduced tillage layer (chroma three month after harvesting . 2), more visible plow pan layer (bulk density clearly higher than the tillage layer above it and the layer below it, and permeability and porosity lower), Fe and/or Mn accumulation layer, and the original soil layer. At higher elevation (Yellowish Brown and Brown Latosols), both the once a year and twice a year of paddy soils, the plow pan layer was found at a shallower depth (10 . 12 cm), while at the lower elevation (Reddish Brown and Red Latosols) it was found deeper (15 . 16 cm), with similar thickness (12 . 19 cm). At higher elevation (Yellowish Brown Latosols), Mn accumulation layer were thicker (72 - 86 cm) than at lower elevation, and in Reddish Brown Latosols (42 - 46 cm). The color of tillage layer of paddy soils is lighter than the lower layer. At harvesting time the chroma 0, three month after harvesting chroma 2, but one year after harvesting if not rice cultivated the colors approach to the original soils colors. The consistence of the tillage layer after harvesting (wet) were very sticky and very plastic, at one to three month no rice cultivation still slightly sticky, but after six to nine month becoming friable to very friable. The pedogenesis processes of paddy soils were Fe/Mn elluviation of tillage layer Fe/Mn illuviation in the lower depth. This indicated by Fed, Feo, and Fep, or Mnd, Mno, and Mnp, and the quantity of Fe or Mn mottles. The tillage layer of paddy soils contain higher weatherable minerals than non-paddy soils, due to mineral materials containing in the irrigation water or mineral material erupted from surrounding volcanoes. In the tillage layer of non-paddy soils, there were processes enrichment, decomposition, lessivage, and leusinization. But of in the paddy soils there were also elluviation and gleyzation. The soil that are regularly cultivated with paddy, there are changes in soil classification, e.i. Typic subgroup of the non paddy soils changes into Aquic subgroup in the once/year paddy soils, and Aquic suborder
Keyword: tillage layer, plow pan layer, manganese layer, iron layer, West Java

Judul: Evaluation of Characteristics of Physical Properties, Chemical Properties and Soil Quality of Post-Harvest Paddy Soil (Case Study: Tuban, East Java)
Abstrak: Tanah sawah pasca panen memiliki sifat yang berubah dan berbeda dengan kondisi ketika sawah diairi, meskipun merupakan kelanjutan dari sifat sebelumnya. Sifat yang berbeda perlu dievaluasi untuk mengetahui kualitas dan tingkat kesuburannya. Penelitian bertujuan mengevaluasi karakteristik sifat fisika dan kimia tanah sawah pasca panen di Tuban, Jawa Timur dan menentukan kualitas tanah serta potensinya untuk penanaman palawija. Metode penelitian menggunakan metode Principal Component Analysis (PCA) dan Minimum Data Set (MDS) dari parameter yang mewakili fungsi tanah untuk analisis kualitas tanah. Parameter yang dianalisis adalah tekstur, bobot isi, pori air tersedia, permeabilitas, C-organik, N total, P-tersedia (P2O5), Kalium dapat ditukar (K-dd), dan Kapasitas Tukar Kation (KTK). Berdasarkan hasil penelitian menunjukkan lokasi penelitian bertekstur klei yang masuk kedalam kategori sedang. Bobot isi berkisar pada 0.8 – 1.4g/cm3 . Pori air tersedia berkisar pada 7.37 – 41.47%. Permeabilitas berada pada rentang 0 – 39.88cm/jam. Kadar C-organik dan Nitrogen relatif rendah. P-tersedia, K-dd, KTK relatif tinggi. Berdasarkan analisis PCA didapatkan tiga parameter sebagai MDS yaitu tekstur, Pori Air Tersedia (PAT), dan permeabilitas. Nilai IKT berkisar 2.60 – 3.43 yang masuk kategori agak rendah dan sedang. Indeks Kualitas Tanah yang dominan pada daerah penelitian adalah sedang. Hasil analisis menunjukkan lokasi penelitian sesuai untuk pengembangan tanaman palawija dan IKT yang rendah dapat ditingkatkan dengan pemberian bahan organik., Post-harvest paddy soil has changed properties and is different from the conditions when the paddy soil is irrigated, although it is a continuation of the previous properties. Different properties need to be evaluated to determine their quality and fertility rate. The study aimed to evaluate the characteristics of physical and chemical properties of post-harvest paddy soil in Tuban, East Java and determine soil quality and its potential for planting crops. The research used Principal Component Analysis (PCA) and Minimum Data Set (MDS) method to select parameters for soil quality analysis. The parameters analyzed were texture, bulk density, available water pores, permeability, C-organic, total nitrogen, available phosphor (P2O5), exchangeable Potassium, and Cation Exchange Capacity (CEC). Based on the result showed that the location of the study has a clay texture which included in the moderate category. Bulk density ranges from 0.8 – 1.4g/cm3 . Available water pores ranges from 7.37 – 41.47%. Permeability ranges from 0 – 39.88cm/h. C-organic and total nitrogen level are relatively low. Available phosphor, exchangeable potassium, and CEC are relatively high. Based on the PCA analysis, there are three parameters obtained as the MDS that are texture, available water pores, and permeability. The Soil Quality Index values range from 2.60 – 3.43, which included in the slightly low and medium categories. The dominant soil quality index in the study area is medium categories. The results of the analysis showed that the location of the study is suitable for the development of secondary crops and SQI low category can be improved by the provision of organic matter.
Keyword: oil Quality Index, Minimum Data Set (MDS), Principal Component Analysis (PCA)

Judul: Konstruksi aritmetika kurva eliptik F(2m) supersingular dan non-supersingular untuk skema kunci publik ElGamal
Abstrak: Algoritme ElGamal adalah salah satu algoritme kunci publik dengan aritmetik modular p yang mempunyai struktur grip siklik Z(p). Tingkat keanaman algoritme ini terletak pada pemecahan masalah logaritme diskret dari Z(p). Akan tetapi, tingkat keamanan tadi tahun ke tahun semakin menurun yang disebabkan kemampuan pemecahan algoritme diskret semakin meningkat. Untuk memenuhi tingkat keamanan yang memadai dibutuhkan p yang cukup besar yang menyebabkan proses enkripsi dan dekripsi menjadi lambat.
Keyword: