Judul: Pengaruh soil conditioner berbasis bahan alami terhadap sifat fisik dan biologi tanah podsolik merah kuning
Abstrak: One type of the most important soil in dry land is Red Yellow Podzolic. These soils have many problems. The main problems in this soil are poor physical and biological properties, it has high bulk density, low permeability, low water holding capacity and low microbial activities. However, this land has a potential, because it covers about 25%-27% of the total mainland of Indonesia. Therefore, soil and water conservation efforts are needed to prevent and repair the poor soil properties. One of soil and water conservation efforts needed is the use of chemical either in the form of synthetic compounds or organic materials that can increase soil aggregate stability and prevent erosion is highly needed. This research was aimed to develop and identify the effect of organic Soil Conditioner based on rice straw organic matter and city organic waste on physical and biological properties of Red Yellow Podzolic Soil. Soil Conditioner used was the compost in the form of briquettes. The experiment was arranged in randomized design with two factors, treatments of soil conditioner include city organic waste, rice straw, and control, with three level of doses, A 1:20, B 1:30 and C 1:40. Each treatment was repeated 3 times to make 27 experimentals units. The results of this research showed that the Soil Conditioner based on city organic waste and rice straw were significantly decreased the bulk density and significantly increased porosity, permeabilty, saturated water content, the water holding capacity, very rapid drainage pores as well as total microbial and total fungi activities of Red Yellow Podzolic Soil.
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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: 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