Judul: Ketersediaan Besi   (Fe)   dan Mangan   dalam  Humic  Dystrudept  dan  Serapannya   Akibat   Pemberian   Beberapa   Bahan   Organik   pada   Budidaya  Tumpangsari   Tanaman   Brokoli   (Brassica   oleraceae)  dan   Petsai   (Brassica  pekinensis)
Abstrak: As alternative way to solve pollution problem that are happened because of modern farming practices is organic farming. The use of organic fertilizers have some real superiority than that of chemical one. Organic fertilizer contains some macro nutirients (N, P, K, Ca, Mg, etc) and micro nutrients (Fe, Mn, Cu, Zn, etc). Besides macro nutrients, these micro nutrients have own role which is needed by crop. Iron (Fe) and manganese (Mn) are two nutrients needed for the growth of a plant. This research was carried out to discover the effect of chickenmanure compost and goat manure compost as well as its combination with pesticides and Thitonia compost on the avaibility of Fe and Mn in soil, their absorption and the production of broccoli and petsai. This research was designed into Group Randomized Design with 6 treatments and 3 replications. Organic fertilizers, those were chicken manure compost (25 ton/ha), goat manure compost (25 ton/ha) and Thitonia compost (3 ton/ha) was applied a the treatments. The results of this research showed that the treatment of organic fertilizers (chicken manure and goat manure as well as its combination) gave significance effect to increase the growth of broccoli but did not increase the growth of petsay, the availability of Fe and Mn in soil and the production of broccoli and petsay. However, there was a tendency that the treatment of chicken manure compost and its combination was higher compared to that of goat manure compost and its combination on all parameter observed.
Keyword: 

Judul: Ambang Batas Fe dalam Pupuk Organik yang Berpotensi Menyebabkan Keracunan Fe Pada Tanaman Padi Sawah
Abstrak: Many scientists reported that intensive agricultural using a high rate of in anorganic NPK fertilizer and pesticide, caused declining in soil productivity, soil degradation, and increased environmental pollution. Organic content of these soils are mostly very low, while it is widely know that organic matter is very important to keep physical, chemical, and biological properties of soil as well as soil productivity. However, the quality and quantity of organic matter to be used are important factor determining the impact on the soil. In Ministry of Agriculture Decree (Permentan) No. 28, 2009, a maximum limit of total iron content in organic fertilizer is 8.000 mg kg-1 while most of the current organic fertilizers available in the market exceed this limit. The objectives of the study were to know the quality of organic fertilizer currently available in the market in Java Island and to determine the threshold level of iron that potentially cause iron toxicity in rice. The survey was conducted on May to July 2011 in java Island for survey and collecting a number of organic fertilizer currently marketed and the pot experiment was conducted on May to November 2011 in green house. This experiment using a randomized complete block design with two factors; the types of soil (Endoaquert, Tropaquept, and Hapludult) and organic fertilizer enriched with Fe (FeCl3) in various level. Each treatment was replicated three times. Survey results from 60 samples of granule organic fertilizer taken from several areas in Java Island with 11 parameters, there was indicated two samples (3 % from the total samples) that fulfilled several criteria following of Permentan No. 28, 2009 and no sample (0%) that fulfilled several criteria following of Permentan No. 70, 2011. The pot experiment results showed that the threshold of total iron content in granule organic fertilizer potentially cause iron toxicity for Endoaquert, Tropaquept, and Hapludult were 62.900, 37.300, and 61.100 mg kg-1 respectively. The threshold of total iron content in granule organic fertilizer potentially cause iron toxicity in rice of IR 64 variety with dose 1 ton/ha is 59.500 mg kg-1.
Keyword: Iron, threshold, organic fertilizer, iron toxicity, wetland rice

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.
Keyword: