Judul: Pengaruh Jenis Pupuk dan Dekomposer terhadap Pertumbuhan dan Produksi Padi Organik
Abstrak: Field experiment was carried out in Cikarawang, Dramaga, Bogor from November 2011 to March 2012. The objective of the research was to study the effect of fertilizer types and decomposer on growth and yield of organic rice. The experiment used factorial-randomized complete block design with fertilizer combinations (15 ton chicken manure ha-1 and 5 ton Tithonia diversifolia ha-1, 10 ton chicken manure ha-1 and 5 ton Tithonia diversifolia ha-1, and 10 ton chicken manure ha-1 and 5 ton rice straw ha-1) as the first factor and decomposer application (using decomposer and without decomposer) as the second factor. Organic fertilizer types significantly affected root wet weight, nutrient content of P and K in leaves. Rice productivities were not significantly different with fertilizer combinations 15 ton chicken manure ha-1 and 5 ton Tithonia diversifolia ha-1, 10 ton chicken manure ha-1 and 5 ton Tithonia diversifolia ha-1, and 10 ton chicken manure ha-1 and 5 ton rice straw ha-1, they were 2.28, 2.22, and 2.16 ton dry seed ha-1, respectively. Decomposer application significantly affected the number of tillers at 8 week after planting, leaf color at 5 weeks after planting, nutrient content of P in leaves and panicle length. Rice yield with decomposer application and without decomposer were 2.25 and 2.19 ton ha-1, respectively, and they were not different.
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Judul: Pemanfaatan Jerami Padi sebagai Pupuk Organik untuk Meningkatkan Pertumbuhan dan Produksi Padi (Oryza sativa)
Abstrak: The leveling off of rice production in Indonesia is mainly caused by degradation of wetlands, which could be characterized by low organic matter content. The factors that cause this issue such as the utilization inorganic fertilizer only, the habit of farmers by carrying out rice straw off from wetland or burning of rice straw. The objectives of this research were (1) to test the ability of decomposers in speeded up the decomposition process of rice straw,( 2) examined the effect of organic fertilizer on the growth and yield of rice. The experiment used completely randomized block design. The treatment was tested of decomposers namely control/no decomposers (D0), decomposers collection of Prof Iswandi Anas, and commercial decomposers. The treatments in field experiment namely NPK 100%, NPK 50%, NPK 50% + PO1, and NPK 50% + PO2 + PB. PO1 and PO2 was an organic fertilizer that each decomposed by D1 and D2, while PB was a bioorganic fertilizer. Application of decomposers in this experiment did not speed up the decomposition of rice straw, because the rice straw had been decomposed. It was indicated by the low C/N. There was a possibility of the presence of decomposers microbes in control because of the straw was saved for 10 days in humid conditions. Application of 50% NPK with organik fertilizer to 100% NPK was not significantly meant application of NPK fertilizer on field research was sufficient at 50% dose, so that the role of organic fertilizer could not be evaluated. However, there was a tendency of enhancing growth and yield of rice in addition of decomposed organic fertilizer by decomposers.
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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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