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.
Keyword: 

Judul: Pengaruh pemberian bahan organik in situ terhadap beberapa sifat kimia tanah di lahan bekas tambang pasir besi di Kabupaten Purworejo Provinsi Jawa Tengah
Abstrak: The iron sand post mining land in the sub-District Grabag, Purworejo District is a critical land that is relatively difficult to be reclaimed. This is due to physical and chemical characteristic of soil that is unappropriate for plant growth. Physically, the post mining land is dominated by sand texture The purpose of this research were to increase the levels of soil organic matter in the sandy soil through the planting of velvet bean (Mucuna pruriens), elephant grass (Pennisetum purpureum Schumach), winged-slack flemingia (Flemingia congesta) and red calliandra (Calliandra calothyrsus) and to analyze the level of soil fertility after the biomass of treatment. The research was tested on experimental plots each measuring 240 m². The treatment plant on each plot were: (1) elephant grass, (2) velvet bean, (3) a combination of elephant grass and Flemingia, (4) a combination of elephant grass and red calliandra, (5) a combination of velvet bean and Flemingia, and (6) a combination of velvet bean and red calliandra. Basic fertilizer were urea, SP-36, KCl and humic compounds. Overall the research area was reaching 4620 m, which makes soils very porous. The sand texture and low organic matter greatly affect the low availability of nutrients. This iron sand reclamation research is conducted by providing in situ organic material with plants that are able to produce high biomass such as legumes, grass, etc. 2 The results showed that the addition of in situ organic materials were able to improve significantly the soil chemical characteristics at the iron sand post mining land. This was seen especially in the parameters of C-organic, N-total, the C/N ratio and CEC which were increased significantly. But these increase in soil chemical characteristics have not been able to improve the soil fertility class of assessment criteria from very low to low within six weeks. . When harvesting, the biomass produced by the plants were cut and then buried under the ground as deep as ± 20 cm and were left for six weeks. The addition of in situ organic materials within six weeks period can not improve the soil chemical characteristics into productive land of agriculture. It was expected with the sustainable addition of in situ organic materials can restore the condition of the land as good as before mining activities
Keyword: 

Judul: Penentuan Nilai Eigen dan Vektor Eigen dari Matriks Tridiagonal 2-Toeplitz dengan Pendekatan Polinomial Chebyshev
Abstrak: The eigenvalues and eigenvectors of a matrix can be determined by finding its characteristic polynomials. The characteristic polynomials of a tridiagonal 2-Toeplitz matrix is shown to be closely connected to polynomials which satisfy the Chebyshev recurrence relationship. If the order of the matrix is odd, then the eigenvalues are found explicitly in terms of the Chebyshev zeros and the eigenvectors are found in terms of the polynomials satisfying the recurrence relationship. For even ordered matrices, the situation is more complicated. The problem in these cases is that although the Chebyshev recurrence formula is still applied, its initial values are not generating Chebyshev polynomials
Keyword: