Judul: Pengaruh Limbah Kulit Samak terhadap Kurva Retensi Air Regosol Dramaga dan Podsolik Jasinga
Abstrak: Leather waste is the residue of the leather tanning process. Since leather waste is by product of organic based industry it may have the potential to be used in agriculture practices. The objectives of this research are to examine the effect of leather waste on water retention curve of sandy and clay soils. Water retention curve were derived from pressure plate apparatus data. The water content of the leather waste of pF 1, pF 2, pF 2.54 and pF 4.2 were respectively 22.85%, 15.66%, 14.79% and 13.29%. The analysis of variance showed that leather waste dosage, soil texture and their interactions significantly affected water content of pF 1, pF 2, pF 2.54 and pF 4.2. Leather waste application tend to shift water retention curve to the left, either in sandy or clay soil. The higher the dosage leather waste the lower the water content. The decrease of water content at higher pF value suggests that leather waste only has the ability to absorb water but not capable to hold them when a pressure is applied.
Keyword: type of soil, soil water retention curve, leather waste

Judul: Pengaruh Aplikasi Basah Water Absorbent Pati Singkong Terhadap Sifat Retensi Air pada Tanah Bertekstur Pasir
Abstrak: Water retention is one of soil physical properties that indicate water availability tobe used by a plant. The low water retention ability is generally owned by sand textured soils such as former mine tailings and other sand texture of soils. Plant on soil with low water retention ability will quickly sustain of water stress that extreme condition will lead to permanent wilting. Common effort to overcome this problem is generally by high frequency irrigation. This effort is however inefficient. Other alterative is needed to solve this problem. Presently BATAN (Badan Tenaga Nuklir Nasional) introduce a Super Water Absorbent (SWA) of Cassava Starch that capable to retain water ± 300 than of it weight. Nevertheless, how the SWA work and influence soil water retention characteristic is still questionable. The study aimed to assess the effect of SWA on soil retention characterstic was carried in a green house of IPB. Results of the study showed that SWA application had no significantly effect on the amount of water retained by soil with very high sand. Organic matter and content of sand are influencing the soil capability in water holding and storing.
Keyword: Bogor Agricultural University (IPB), water retention, super water absorbent, sand textured soils

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
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