Judul: Meningkatkan pelepasan unsur hara dari batuan beku dengan senyawa humat
Abstrak: One of alternatives that can be used to increase the nutrient elements release from igneous rocks is reaction with humic substances. This research aims to study the ability of humic substances to increase the nutrient elements release and improve the release from igneous rocks. The humic substances, in the form of salt and acid, are extracted from peat and lignite. Three kinds of igneous rocks were treated i.e. basalt porphyry, diorite porphyry and trachyte porphyry with three grain size i.e. 60 - <2000 μm, <60μm and (1x1x0,3)cm3 . the rocks were impregnated with humic substances for 5 weeks. The result showed that the peat humic substances in the form of peat humate can increase the nutrient elements release from igneous rocks in size <1000μm. Nutrient elements release in basalt porphyry showed better results than diorite porphyry and trachyte porphyry. Release process of element from minerals in igneous rocks occur in the field boundaries between crystals, crystals cleavage, and the crystals surface.
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Judul: Efektivitas campuran bahan humik dengan zeolit terhadap pertumbuhan dan ketersediaan unsur hara tanaman
Abstrak: Penelitian ini dilatarbelakangi oleh penggunaan pupuk buatan dengan dosis tinggi dan terus menerus yang mengakibatkan dampak diantaranya tanah menjadi keras, stabilitas tanah terganggu, serta terjadinya pencemaran lingkungan. Penggunaan bahan organik sebagai pupuk organik dapat dipertimbangkan sebagai salah satu alternatif untuk memecahkan masalah tersebut. Bahan humik (bahan terhumifikasi dari bahan organik) diketahui dapat memperbaiki kesuburan tanah dan membantu pertumbuhan tanaman. Oleh karena itu sangatlah tepat untuk memanfaatkannya seoptimal mungkin. Bahan organik yang cukup potensial untuk dimanfaatkan adalah gambut. Penggunaan mineral zeolit pada penelitian ini adalah sebagai penyerap bahan humik sehingga mempermudah aplikasi penggunaannya. Tujuan dari penelitian ini adalah melihat efektivitas campuran bahan humik dengan zeolit terhadap pertumbuhan dan ketersediaan unsur hara bagi tanaman. Bahan yang digunakan adalah bahan humik yang diekstrak dari gambut dengan menggunakan larutan 0.1 N NaOH. Bahan humik tersebut dicampur dengan zeolit. Perlakuan yang diberikan adalah bahan humik dengan kadar 0%, 0.8%, 1.6% dan 2.4% yang masing-masing taraf dibuat dalam takaran 25 g, 50 g dan 75 g per pot dan masing-masing perlakuan diulang sebanyak 3 kali. Parameter yang diamati adalah tinggi tanaman, bobot basah dan bobot kering tanaman. Analisa yang dilakukan meliputi analisa tanah yaitu pH, basa-basa dapat dipertukarkan (Ca, Mg, K, Na), KTK dan KB. Sedangkan analisis jaringan tanaman meliputi N, Ca dan Na. Hasil penelitian menunjukkan bahwa pemberian bahan humik dengan zeolit dapat meningkatkan pertumbuhan tanaman bayam dibandingkan perlakuan tanpa bahan humik. Dengan meningkatnya kadar bahan humik yang diberikan pertumbuhan tanaman menjadi terhambat hingga takaran 50 g per pot. Sedangkan untuk takaran 75 g per pot dengan semakin meningkatnya kadar bahan humik yang diperlakukan dengan takaran zeolit yang lebih tinggi ternyata pertumbuhan tanaman menjadi lebih baik…dst
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Judul: Thermal Characteristics and Dynamics of Tropical Cyclone over Western North Pacific Ocean: A Case Study of Typhoon Songda (Chedeng) 2011
Abstrak: The frequent occasion of Tropical Cyclone (TC) over Western North Pacific (WNP) Ocean lies from 10˚N to 26˚N and 121˚E to 170˚E. Sources of TC development come from warm ocean temperature where latent heat is released during condensation processes and subsequently concentrated in the boundary layer. Relative humidity at 850-700 hPa is responsible to produce the most intense storm. Meanwhile, weak vertical wind shear between 850-200 hPa is one of the dynamical factors that lead to the development of TC. Pressure level of 850-200 hPa is chosen to minimize the thermodynamic effect in the lower troposphere. Typhoon Songda (Chedeng in the Philippines) or TSC lasted from May 18th to 30th, 2011 and strengthened into powerful Super Typhoon stage between May 24th and 27th. Long curving track and the exhibition of all sequences of TC life cycle, TSC is then considered as an ideal case of TC. The objective of the study with case of TSC is to investigate the role of thermal characteristics and dynamics on TC intensity. The research is carried out by using Advanced Research of Weather Research and Forecasting model (WRF ARW model) version 3.3. Two domains are employed in the model. The first domain situate from 02˚N to 40˚N and 118˚E to 149˚E and cover spatial resolution () of 33.1 km. The second domain situate from 09˚N to 27˚N and 119˚E to 132˚E with of 11 km. Timestep of the model () is 120 seconds. The model is supported by the following physical parameterization, i.e., Yonsei University Scheme (YSU) in the boundary layer, Kain-Fritsch scheme (KF) in the cumulus, and WRF Single-Moment 3-class scheme in the microphysics. Initial meteorological condition prior to the formation of the cyclone is generated using WRF ARW standard-release model. Sensitivity of the model output is obtained from a selected single-parameter change scenarios, namely, 10 % to 20 % decrease and increase of wind shear initial data at 850-200 hPa, and by 10 % to 20 % decrease of relative humidity initial data at 850-700 hPa. The result showed that the negative correlations between wind shear and intensity are found in wind shear scenarios. Wind shears of 10 ms-1 which lead to strengthening of the wind intensity in the early period of Typhoon development are found in wind shear scenarios. The effect of wind shear changes on wind intensity is statistically significant in the 20 % wind shear scenarios. During mature stage, weak wind intensity occurred when wind shear increase as given in the WRF standard-release and the 20 % decreasing scenario. Different situation is found in the 20 % increasing scenario where wind shear tend to weak and lead to strong wind intensity at this stage. Meanwhile, the reduction of moisture supply at 850-700 hPa resulting from 20 % decreasing relative humidity play a major role in the weakening of wind intensity and reduces mechanical energy of the cycle process as much as 300 J kg-1.
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