Judul: Perbaikan Tanah Media Tanaman Jeruk dengan Berbagai Bahan
Abstrak: Addition of compost can improve the properties of soil, but it is rarely used although it has many benefits to soil. On the other hand, the use of ex situ material has been found in many places. Organic substances that easily available in situ are effective as compost materials. This research used five in situ organic substances with the objectives: to know the nutrient content of compost that have been used, to see the influence of compost addition to soil properties and citrus growth, and to find the compost type that giving the best influence to the growth of citrus crop. This research analyzed the physical, chemical, and biological properties of soil, and analyzed the nutrient content of the crop. The results of this research indicated that the nutrient content of compost depended on its origin. Compost influenced the properties of soil beginning three months after compost application that was showed by the increasing of nutrient availability. Compost also influenced the earthworm population where 906 worms/m2 have been found after six months of application of straw compost, and 1099 worms/m2 after application of grass compost. Compost application influenced physical properties of soil that encourage “the piled soil” (trumbuk) porosity, through improvement the composition of soil. After six month of application, the growth of the citrus plant was slightly influenced by addition of compost, this can be seen from the nutrient content of the plants, but from the amount of citrus fruits were shown clearly that application of cattle dung and banana tree compost could increased the yields.
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Judul: Perbaikan lahan bekas tambang pasir besi dengan aplikasi bahan humat dan kapur untuk tanaman semangka (Citrullus vulgaris scard)
Abstrak: Activities in iron sand mining affects the degradation of physical and chemical properties of soils. Several soil problems of ex-mined land of iron sand mining are low nutrient availability, low available soil water, high soil temperature, porous structure and uneven topography. Improvement of the such soil needs application of appropriate soil ameliorants such as humic substance and lime. It has been known that humic substance can be obtained by extracting organic matter, therefore, application of that material may improve the chemical, physical, dan biological properties of soil. The purpose of this research is to examine the effect of humic substance and lime application on ex-mined land of iron sand mining on soil characteristics, growth, and production of watermelon. The research was conducted in ex-mined land of iron sand quarry of PT. Antam (Aneka Tambang) at Patutrejo, Grabag village, Purworejo, Central Java from March 2010 until March 2011. The field research used Split Plot of Complitely Randomized Design consisted of two factors: Humic substance (H0: 0; H1: 7.5; H2:15; and H3: 22.5 L/Ha) and Lime (K: 0 and K1:100 kg/Ha) with three replications. The parameters of growth and production (shoots length, leaf number, segment number, male flowers number and fruit weight) were measured to determine the effect of the treatments. The chemical properties of soils were analyzed for monitoring the soil properties changes. The results showed that humic substance and lime application increased the availability of P, K, Ca, and Mg. Humic substance has carboxil and fenolic clusters those have capability to bound Al and Fe ions from soil solution for forming low solubility of complex compounds. Therefore, the concentration of free Al and Fe ions in the solution will decrease causing the available of phosphate increase. Humic substance increased the shoot length, leaf number, male flowers number, and the segment number. The application of humic substance as much as 22.5 L/Ha increase the watermelon production by 28% from 6.15 ton/Ha at K0H0 to 7.88 ton/Ha at K0H3 treatment. Leaf spot disease, soft rot, and pest snails affected growth and yield of watermelon.
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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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