Judul: Uji inokulum rhizobia dan pengaruhnya terhadap pertumbuhan Acacia mangium pada tanah masam bekas tambang
Abstrak: Acacia mangium is a legume plants, which became widely known in Indonesia. This plant can make symbiosis with rhizobia to form nodules on legume crops in order to fix nitrogen for the needs of plants. In addition, it also has the ability to adapt in marginal lands, rapid growth, and good characteristhic of wood. Thus, this plant is used to fulfil the needs of industry and potential to be developed as a commodity of Industrial Timber Estates. Generaly the symbiosis between rhizobia and A. mangium can grow well only in neutral soil. However this symbiosis also has been found in acid soil and very acid soil. In this research, there were three inoculant treatments isolated from nodules of A. mangium which grown in three different places. They were KPC inoculant treatment and Kampus inoculant treatment represented acid soil, and also RR inoculant treatment represented very acid soil. Each treatment was given one ml of rhizobia inoculant. The fertilizers given were urea and KH2PO4, i.e. 0.12 g/polybag equivalent to 240 kg/ha urea and 0.08 g/polybag equivalent to 160 kg/ha KH2PO4, respectively. The plant growth media were made from the ex-mining acid soil and cow dung with ratio of 1:1 and the pH was 3.68. Analysis of variance showed that rhizobia inoculant treatment significantly increase the availability of ammonium and nitrate in the soil for all treatments. KPC inoculant treatment had the highest value of ammonium and nitrate in soil, also N plant uptake i.e. 73.1 ppm, 251.7 ppm, and 94 mg, respectively. Then, followed by RR inoculant treatment i.e. 57.4 ppm, 233.7 ppm, and 93 mg respectively. Meanwhile, RR inoculant treatment had the highest value of N-total concentration that is 2.79%. In the RR inoculant treatment occured “the concentration effect” where the N-total concentration was high but the N plant uptake was low. In the other way, KPC inoculant treatment had lower N-total concentration than RR inoculant treatment, but the plant N uptake was higher than RR inoculant treatment, this is called as “the dilution effect”. The results showed that KPC and RR inoculants treatment significantly increase dry weight of upper plant, N-total concentration, and N plant uptake. The addition of rhizobia inoculant significantly increase the value of ammonium and nitrate in soil also N-total concentration and N plant uptake in all treatments as compared with control plant.
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Judul: Penggunaan Rhizobium Dan Mikrob Pelarut Fosfat (MPF) Untuk Memperbaiki Pertumbuhan Bibit Akasia (Acacia mangium dan Acacia crassicarpa)
Abstrak: The increasing of paper raw material requirement is caused by the development of raw material. Therefore, it is needed a method to produce a high quality and quantity of paper. Acacia is one of paper raw material. To increase the growth of acacia seed, an effective usage of Rhizobium and Phosphate Solubilizing Microbe (pSM) seedling inoculant is one of strategies to produce good acacia seeds. The Rhizobium and Phosphate Solubilizing Microbe seedling inoculant can reduce anorganic fertilizer usage and increase the growth of acacia seed. The aims of this research were to select Rhizobium which has an ability to fix atmosphere N2 air and local Phosphate Solubilizing Microbe in dissolving phosphate, also to test the ability of those isolates in increasing the growth of acacia seedling. This research was conducted in the Soil Biotechnology Laboratory, Department of Soil and Land Resource Science, Faculty of Agriculture, Bogor Agricultural University and RAPP greenhouse (Pelalawan and Pangkalan Kerinci R&D Nursary) in Riau. Plant media is cocopit. The experiment consisted of 15 Rhizobium treatments isolated from peat soil, which was planted with A. crassicarpa, and mineral soil, which was planted with A. mangium; 16 Phosphate Solubilizing Microbe treatments taken from peat and mineral soil with 5 replications . The research resulted 2 Rhizobium isolates from IS tested isolates, which could increase the growth of A. crassicarpa effectively, those were Rh Ac S and POS-RIS, and 2 Phosphate Solubilizing Microbe from 16 tested isolates, those were BPF 4 and FPF S. While on A. mangium, there were 2 isolated out of 15 Rhizobium isolates which could increase the A. mangium growth effectively, those were M32-M33-R2N and M45-R2N; also 3 isolates out of 16 Phosphate Solubilizing Microbe, those were M32-BP3, FRK2, and M33-FP2. The characteristic of effectiveness could be seen from the plant height, the amount of leaves, the dry root wight, the dry plant weight, the diameter of bar and the root compactness; so that the usage of Rhizobium inokulan, Rh Ac 5 and P05-RIS equal to the usage of 0.1 kgll Monopotassiumphosphate fertilizer and better than control. Meanwhile the usage of MPF, BPF 4 and FPFS equal to the usage ofO.SI1 kg of Osmocote fertilizer and better than control.
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Judul: Hamiltonian formulation for linear waves motion in two layers fluid
Abstrak: The surface wave could be considered as a wave that separates two fluids, namely water and air. Based on this assumption, it is introduced the interfacial wave, a wave between two layers of fluid with different density. The formulation of interfacial waves motion begins with deriving the base equation of irrotational ideal fluid. Furthermore, according to irrotational fluid assumption, the base equation can be stated in velocity potential. In this derivation, the fluids domain is assumed to be restricted by rigid lid boundary conditions, both at the upper and lower limit. Therefore, the interfacial waves motion can be explained in a hamiltonian formulation. In the hamiltonian formulation, total energy is defined as the sum of kinetic and potential energy. The hamiltonian system is obtained from reduction of kinetic energy by using the Dirichlet Neumann Operator. The resulted kinetic energy equation is nonlinear. Therefore, this form is linearized by first part of the Taylor expansion. This linearization gives a dispersion relation of linear wave. Based on this dispersion relation, the phase speed of the linear wave depends on the density ratio of the two layers fluid.
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