Judul: Addition of Plant Growth Promoting Rhizobacteria to Improve the Quality of Organic Fertilizer, Nutrient Uptake, Growth and Yield of Upland Rice and Maize
Abstrak: Biofertilizer is one of the alternative fertilizers that can increase nutrient uptake, plant growth and production. The purpose of this research was to evaluate the quality of organic fertilizer (compost) enriched with bofertilizer and its effect on nutrient uptake, growth and yield of upland rice and maize. This experiment was conducted using a Randomized Block Design with two factors of treatment. The first factor was organic fertilizer that consist of three levels: compost without biofertilizer as a control, compost enriched with biofertilizer, compost and biofertilizer applied separately on the day of planting. The second factor was the anorganic fertilizer consisting 2 levels: 50% and 100% of recommended doses. The upland rice var Situbagendit and maize var Bisma were grown on the field condition. The bacteria used as biofertilizer were Bacillus subtilis strain HU48, Pseudomonas beteli strain ATCC1986IT, Azotobacter sp. strain HY1141, dan Azospirillum sp. strain NS01. The compost enriched with biofertilizer had the best effect on most variables observed including nutriet uptake, growth, biomass, and production of both crops. This enriched compost increased macro and micro elements uptake of upland rice and maize. This treatment increased the production of upland rice up to 73% while the maize production increased up to 38%. Anorganic fertilizer increased significantly the macro nutrient uptake in upland rice but not in maize. In comparison with 50% dose of anorganic fertilizer, 100% dose anorganic fertilizer increased the plant growth and yield of upland rice and maize. However, this increase was not significant. The best treatment was showed by compost enriched with biofertilizer that was combined with 100% anorganic fertilizer. This treatment increased grain weight up to 109,28% of upland rice, and seed weight up to 41,18% of maize compared to control.
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Judul: Kombinasi antara Pupuk Hayati dan Sumber Nutrisi dalam Memacu Serapan Hara, Pertumbuhan, serta Produktivitas Jagung (Zea mays L.) dan Padi (Oryza sativa L.)
Abstrak: The continues utilization of anorganik fertilizer might result in depletion of soil fertility. The objective of this research was to evaluate the effect of biofertilizer and nutrient sources in improving nutrient uptake, growth and productivity of maize and rice. The experiment was conducted in the plastic house Cikabayan IPB Farm for maize, while for rice it was held in a green house of Balai Besar Biogen Cimanggu, Bogor, West Java. Randomized Block Design was used for experimental design using 2 X 4 factors with 5 replications. The first factor is biofertilizer treatment which consist of application of biofertilizer (H1) and without biofertilizer as control (H0). The second one is the type of nutrient sources that comprise of 4 levels: Soil (N0), Soil + 100 % dosage of anorganik fertilizer (N1), Soil + 100 % dosage of compost (N2), Soil + 50 % dosage of compost + 50 % dosage of anorganic fertilizer (N3). The biofertilizer consist of Azospirillum sp., Pseudomonas sp., and Bacillus sp. selected by the Laboratory of Mikrobiologi, Bogor Agricultural University, Darmaga, Bogor, West Java. Each isolate was enriched in broth medium with the population of 108 cell/ml. The dosage of biofertilizer was 15 ml per pot. The dosage of anorganic fertilizer was 250 kg/ha Urea; 200 kg/ha SP-36, and 200 kg/ha KCl, whereas the compost dosage was 10 ton/ha. The result showed that application of biofertilizer significantly improved nutrient uptake, growth and productivity of rice and maize. For maize, the application of biofertilizer increased macronutrient uptake by 50-97 %, micronutrient uptake by 58,9-63,2 %, dry weight of plant up to 53,7 %, and dry weight of seed up to 36,6 %. For rice, application of biofertilizer resulted in an increase of macronutrient uptake by 10,9-22,5 %, plant dry weight 11,6 %, and total weight of rice seed 7,2 %. The result also showed that the nutrient sources significantly affect the nutrient uptake, growth and productivity of maize and rice. In maize, the highest macronutrient and micronutrien uptake (4,5 g/pot and 10,4 mg/pot respectively) and dry weighy of seed (36,6 g/pot) resulted from the treatment of N2, while the highest dry weight of plant resulted from N3 (6,9 g/pot). For rice, N2 treatment had the maximum macronutrient uptake (2,7 g/pot). The highest micronutrient uptake (5,9 mg/pot), dry weight of plant (41,4 g/pot), and total weight of rice seed (32,8 g/pot) resulted from the treatment of N3. In maize, the N2 treatment in combination with biofertilizer resulted in the highest seed dry weight (41,6 g/pot) and increased productivity by 97-137 % as compared to the treatment of N1 and N3. In rice, the combination treatment of N3 and biofertilizer resulted in the highest weight of rice seed (33,4 g/pot) as compared to the others.
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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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