Judul: Populasi Mikrob Tanah Latosol Darmaga yang diinkubasi Soil Conditioner Berbahan Kompos Jerami Padi
Abstrak: Latosol that is found widespread in Indonesia, has characteristics such as it contains much aluminium and Iron oxides, deficient in plant nutrients due to excessive leaching, reddish in color, horizons in the soil profile are not distinct and deep solumn (over 150 cm). Soil conditioner has an important role in improving soil phyical properties such as stimulating granulation, soil aeration and water holding capacity. Soil conditioner from rice straw compost could also enhance beneficial microbial population and their activity, such as nitrogen fixers, phosphate solubilzers and cellullose decomposers. Organic matter accumulation, nutrient cycles and the formation of stable soil structure are strongly influenced by soil organism activities. Thus, the use of soil conditioner on Latosols is expected to improved the physical, chemical and biological properties of soils. This research aims 1) to evaluate the microbial (bacteria and fungi) population in soils incubated by soil conditioner made from rice straw compost, 2) to study the relationship between microbial population and some soil physical properties (aggregate stability and soil moisture). The experiment was arranged using completely randomized designed with two factors i.e. 1) the treatment of soil conditioners (with and without soil conditioner) and 2) incubation time (2 and 6 months). The treatment was replicated three times, thus resulted in 12 experimental units. The result showed that soil conditioner significantly increased soil moisture content, compared to the control. After six months incubation, soil conditioner had no effect yet on the soil aggregate stability and soil microbial population, compared to the control
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Judul: Pemanfaatan kompos jerami padi dan sampah pasar sebagai soil conditioner
Abstrak: Generally, dry land of agriculture is characterized by low soil fertility and availability of water for irrigation depend on rainfall. Therefore, development dry land agriculture is required conservation efforts intended to improve soil structure, reduce erosion, minimize loss of nutrients and increase water availability. Improvement of physical, chemical and biological soil properties can be done by using soil conditioner. This research aimed to formulate soil conditioner from rice straw raw material, waste vegetables market, cow dung and biochar. The research was conducted on April to September 2010 in plastic house was build in the field of university farm of Bogor Agriculture University in Cikabayan Darmaga, Bogor. Physical and chemical analysis were conducted in the laboratory of Department of Soil Science and Land Resources, Faculty of Agriculture, IPB, whereas biological analysis was conducted in the Plantation Research Institute. The research was initiated with the composting of rice straw and waste vegetables market materials. The resulting compost was used as the base material to formulate soil conditioner which were enriched by biochar, extraction of goat urine and manure and CuSO4. The results showed that the largest compost material depreciation occurred in compost D and B of 69,29% and 54,7%, respectively. Average of saturated water content of all compost were over than 200%, while bulk density were 0,36 g/cm3 (compost D), 0,29 g/cm3 (compost C), 0,22 g/cm3 (compost A) and 0,15 g/cm3 (compost B). Macro nutrients content (N, P, K and Mg) in compost C and D were lower than compost A and B, on the contrary Ca content of compost C and compost D were higher than compost A and B namely were 1,16% and 3,16%, respectively. Total population of microorganisms was different for each type of compost. The highest fungal population was found in compost A (5.05 x 105) and the highest bacterial population in compost C (4.45 x 1011). Compost which were formed from materials A and B were the best compost due to has a lower bulk density and higher of nutrient content (N, P, K, Mg, Fe, Cu, Mn, Zn and total fungal) comparing with C and D materials. The bulk density of briquettes soil conditioner after compaction treatment was 0,64 gr/cm3. Soil conditioner B has a higher of macro and micro nutrients contents than soil conditioner A, C and D. Soil conditioner A has a higher colonies of fungal (9.3 x 106) and soil conditioner D has a lot of colonies of bacteria (5,05 x 1011). Based on the nutrients content, soil conditioner with formulation B is the best formulation as compared with formulations A, C and D.
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Judul: Closed Knight’s Tour pada Papan Catur Berbentuk Persegi Panjang dengan Ukuran Maksimal 8 × 8
Abstrak: Closed Knight’s Tour merupakan langkah kuda yang mengunjungi setiap kotak pada papan catur tepat satu kali dengan langkah kuda berawal dan berakhir pada kotak yang sama. Graf yang terbentuk dari closed knight’s tour dinotasikan sebagai graf G(m,n), dengan m adalah banyaknya baris dan n adalah banyaknya kolom. Graf tersebut memuat Hamiltonian cycle. Sebuah graf terhubung G adalah graf bipartite jika dan hanya jika graf tersebut tidak memiliki cycle dengan panjang ganjil. Papan catur yang memenuhi syarat cukup untuk memiliki closed knight’s tour adalah papan catur berukuran 5 × 6, 5 × 8, 6 × 6, 6 × 7, 6 × 8, 7 × 8, dan 8 × 8.
Keyword: bipartite, closed knight’s tour, hamiltonian cycle, knight’s tour, teori graf