Judul: Studies on Infiltration at Various Tropical Soil Textures
Abstrak: Understanding how water infiltrates and how fast water moves through soil play important role for agricultural planning such as development of plant irrigation, fertilizer and soil nutrition movement, surface and subsurface water pollution, and groundwater recharge. Because of the available data that obtained from direct measurement are very limited, therefore it is necessary to apply indirect method for simulating infiltration process in soil by taking into account soil physical and hydraulic properties which is collected during soil sampling as the predicting variables. The model used in simulation must be able to describe distribution of pressure head and soil water content along with the infiltration process. Objectives of the research are to optimize soil water retention function parameter of various tropical soil textures; to assess numerical simulation for solving the problem of one dimensional infiltration into a deep and homogeneous soil; and to simulate cumulative infiltration of various soil textures. Soil texture was classified based on International Society of Soil Science (ISSS) classification using distribution of sand, silt, and clay fraction. Soil water retention function of Van Genuchten was optimized using 165 soil sample data collected from Flores, Kotawaringin Barat, Samarinda, Kutai, dan Gorontalo. Combining error terms by a root-mean-square and changing to the finite difference form of the equation variables was applied to analyze error of water retention and hydraulic conductivity function. Numerical procedures of Crank-Nicolson semiimplicit discretization combined with Newton method and elimination technique of Thomas algorithm was used to solve one-dimensional Richards-Darcy’s equation. The Green and Ampt, and Philip infiltration model was used to find the length of wetted zone and sorptivity at each soil textures. Source code of programming was written in BASIC using Visual Basic for Application in Microsoft Excel. Soil water retention function parameter was optimized for 10 ISSS soil textures that is heavy clay, sandy clay, sandy clay loam, sandy loam, sand, light clay, clay loam, loam, silty clay, and silty clay loam. Result of simulation showed that Richards-Darcy’s equation was able to simulate infiltration process in soil by taking into account soil physical and hydraulic properties as the predicting variables. The output of simulation includes tabulated values and graphics representing the cumulative infiltration and the pressure head, water content, and unsaturated hydraulic conductivity profiles at different times. The results showed that sand, loam, sandy loam, heavy clay, and light clay soil textures have the largest to smallest cumulative infiltration and depth of wetted zone with time elapsed respectively.
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Judul: Keragaan Infiltrasi Tanah Latosol pada Beberapa Penggunaan Lahan di DAS Ciujung
Abstrak: Land use is an important aspect in maintaining ecosystem sustainability, particularly in the watershed ecosystem. Land use determines to physical, chemical, and biological characteristics of soil. These soil characteristics influence to the growth of plants and the performances of water infiltration into soil. Infiltration is an essential part of the hydrological cycle that has an important role water availability in the soil. Infiltration process have an important role to the distribution of rainfall and control to runoff, flood, erosion and ground water storage and finally will determines the availability of river discharge in dry season. The aims of this research is to assess the performance of soil infiltration in various land use in Ciujung watershed. The study was conducted on three land use types that included plantative forest (HT), dense mixed garden (KCR), and less-dense mixed garden (KCTR). The field observation was done by using the Double Ring infiltrometer method, while the the analysis of the physical and chemical and other soil characteristics were done in the Laboratory of Soil and Water Conservation, Department of Soil Science and Land Resources, Faculty of Agriculture. The results of this research showed that the infiltration rate is strongly influenced by land use. Infiltration rate is the highest and most stable on HT land use, followed by KCR and KCTR. Constant infiltration rate at HT and KCR is belonging to quickly class, while at KCTR is relatively moderate to fast. The magnitude of the rate constant infiltration in HT (23.4 cm h-1) is higher than KCR (13.2 cm h-1) and KCTR (6.0 cm h-1). The high rate infiltration of the soil on the land use of HT support it able to accommodate as much water (6.45 dm3) that higher than at KCR (3,66 dm3) and at KCTR (1.52 dm3). Infiltration rate is influenced by pores with large size (PDSC), while the volume of water infiltration is more influenced by the total porosity of the soil. Besides it is influenced by land use, soil infiltration in the study area is also determined by the physical and chemical characteristic of the soil organic matter, bulk density, total porosity, aggregate stability, macro pores, very fast drainage pore (PDSC), and soil texture.
Keyword: Bogor Agricultural University (IPB), infiltration volume., physical and chemical characterstics of soil, land use, Infiltration rate

Judul: Psittacosis Sebagai Zoonosis Penting Yang Berasal Dari Burung
Abstrak: Psittacosis atau ornithosis adalah penyakit menular dari burung kepada manusia. Agens penyebab psittacosis termasuk ke dalam virus psittacosis-lymphogranuloma venereum group yang disebut Chlamydia psittaci. C. psittaci hanya dapat berkembang biak di dalam jaringan hidup tetapi peka terhadap antibiotik. Penyebaran penyakit ini sangat luas, terdapat hampir di seluruh dunia. Di Indonesia penyakit ini belum pernah di diagnosa, tetapi mengingat terdapat demikian banyaknya jenis burung maka diperkirakan psittacosis ini sudah ada. Kasus pada manusia pertamakali ditemukan oleh Ritter pada tahun 1879, di Eropa. Waktu itu dikenal sebagai pneumotyphus. Chlamydia psittaci tidak hanya sebagai penyebab infeksi pada burung, juga bisa menyebabkan infeksi pada mamalia diantaranya sapi, kerbau, kambing, domba, babi dan kucing. Pada kucing dikenal sebagai feline pneumonitis. Pada domba atau kambing mengakibatkan enzootic abortion. Pada burung, kalkun merupakan unggas paling rentan diikuti oleh burung psittacine dan burung lain di luar famili psittacidae. Virulensinyapun berbeda-beda. Yang berasal dari kalkun bervirulensi tinggi, sedangkan yang berasal dari burung merpati bisa bervirulensi tinggi bisa juga bervirulensi rendah. Penularan terjadi melalui kontak langsung maupun ti- dak langsung. Penularan melalui telur tidak terjadi. Umumnya penyakit ini memperlihatkan gejala klinis berupa deman, lesu, lemah, anorexia, kurus, diarrhea ber- warna kekuningan, discharge dari mata dan hidung, conjunc- tivitis. Gejala khas pada kalkun adalah istirahat dengan sternum sebagai dasarnya, karena adanya tekanan dari bagian perut yang sakit. Sedangkan pada manusia memperlihatkan adanya demam, kadang-kadang merasa dingin, lesu, sakit kepala yang hebat, sakit pada bagian belakang badan dan photophobia…dst
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