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51.
52.
Ebenezer Annan-Afful Noriko Iwashima Ernest Otoo Kwame Osafredu Asubonteng Daisuke Kubota Akira Kamidohzono 《Soil Science and Plant Nutrition》2013,59(5):649-664
The bulk density and nutrient distribution in soil profiles as affected by various land use systems were studied. Mean bulk densities of the various soil profiles, 0-20, 20-40, and 4060 cm in the selected five land use systems along the upland / lowland topo-sequences were, 1.26, 1.73, and 1.44 Mg m-3 for the primary forest (PF) plot in the upland area, 1.13, 1.51, and 1.50 Mg m-3 for the cacao farm (CP) plot, 1.16, 1.63, and 1.26 Mg m-3 for the mixed cropping (MC) plot, 1.39, 1.61, and 1.50 Mg m-a for the fallow (Fallow) plot, all three land use systems being in the upland / fringe areas, and 1.46, 1.72, and 1.60 Mg m-3 for the lowland traditional rice farming (TR) plot, respectively. The very high bulk density of the second layer, especially in the PF plot, may be related to the hardening of the iron / quartz stone layer due to prolonged dry conditions, which may affect plant growth and hydrological cycles in the benchmark inland valley watersheds. The TC contents of the topsoil samples were 43, 32, 24, 26, 18, and 15 g kgm-1 for the PF, CP, Fallow, MC, TR, and sawah (Sawah) plots, respectively. The C / N ratios of the topsoil samples were 10, 10, 9.8, 9.1, 8.8, and 8.8 for the CP, Fallow, MC, Sawah, TR, and PF plots, respectively, displaying a higher natural fertility, especially for the N supply in the PF plot in the upland area. The available phosphorus levels were low even for the topsoil samples, 1.8 to 3.4 mg kg-1 for the upland soils while the lowland TR and Sawah plots recorded values of 4.4 and 4.9 mg kg-1, respectively. The contents of exchangeable K, 0.1-0.4 cmole kg-1, of the topsoil samples were in the range of those of normal inland valley soils in West Africa. In contrast to the content of available P, although the MC plot showed a depletion, the PF, Fallow, and CP plots showed a replenishment of available K through biological nutrient cycling. The levels of exchangeable Ca and Mg as well as eCEC, were also relatively high compared to those of mean inland valley soils in West Africa. The major component of eCEC was Ex. Ca. The levels of Ex. Ca in the topsoil samples were 11.1, 9.1, 7.8, 4.7, 5.1, and 3.9 cmolc kg-1 for the PF, CP, Fallow, MC, TR, and Sawah plots, respectively. The distinctive feature of Ex. Mg was its large distribution in the upper soil profiles in the CP plot, indicating that in the cacao farms, Ex. Mg was enriched, probably due to the high level of Mg in the leaf litter. The lowland soils, normally, should have been enriched in exchangeable bases such as Ca, K, and Mg, leading to a higher eCEC value and higher general fertility through the process of geological fertilization, Le., nutrient flows from upland to lowland areas, as in the case of lowland sawah in monsoon Asia. At the benchmark sites, however, the effects of the geological fertilization process were not evident. This is one of the most important characteristics of West African inland valley watersheds. 相似文献
53.
Takaaki Itai Teruyuki Maruoka Minoru Kusakabe Kenji Uesugi Muneki Mitamura 《Soil Science and Plant Nutrition》2013,59(3):450-454
Abstract In this paper, we proposed a new approach for on-site colorimetric analysis of ferrous ions (Fe2+) and ammonium-nitrogen (NH4 +-N) using a soil color meter as an alternative method to conventional spectrophotometry. The soil color meter we used can express solution color numerically on the basis of L*a*b* color space. After coloring of water by the 1, 10 phenanthroline method and the Indophenol blue method, the color of solution was measured by the soil color meter. A linear relationship between Fe2+ and a* or b* values, and systematic change of NH4 +-N with L* value, enable us to make a calibration curve. The Fe2+ and NH4 +-N concentrations in groundwater samples (Fe2+: 0.3–1.3 mg L?1; NH4 +-N: 0.02–0.62 mg L?1) determined by the proposed method agreed well with those determined by conventional spectrophotometry with the difference being ± 0.05 mg L?1 and ± 0.02 mg L?1, respectively. Since a similar apparatus is widely used in the soil science field, this technique would facilitate field surveys. 相似文献
54.
Kiyohiko Nakasaki Nobuyuki Uehara Minoru Kataoka Hiroshi Kubota 《Compost science & utilization》2013,21(4):47-51
The effect of Bacillus licheniformis HA1 cell density on the acceleration of organic waste composting was tested in a bench-scale composting system utilizing a process limit temperature of 60°C. Variables measured during composting were CO2 evolution rate, conversion of substrate carbon and pH. When an initial cell density of 2.0×104 cfu/g-dry solid was used, the strain HA1 increased in number and prevented the decrease in pH during the early stage of composting. This resulted in enhanced populations of other thermophiles and increased the rate of organic matter decomposition. By contrast, no effect was observed at a lower cell density of HA1. It was found that the minimum cell density of HA1 to accelerate organic decomposition was around 104-105 cfu/g dry solid of raw material. 相似文献
55.
Urbanization is expanding in and around small to medium-sized cities as well as in large cities, and the expansion includes low-lying areas where the flood risk is high. Flood risk in small watersheds has been evaluated using precise mathematical models. However, these models cannot be applied to larger basins due to the complexity of data collection and analysis. As a result, quantitative evaluations of flood risk at macro scales and the flood-prevention function of paddies around urban areas have not been made. This paper proposes a method and an index that can be used to evaluate the flood-prevention function of paddies on a regional scale. In addition, the use of this system for basin-wide management is illustrated by an example for the Kinu and Kokai rivers, which are tributaries of the Tone River of Japan. The applicability of the approach is evaluated using data from a major flood that occurred in the study area. 相似文献
56.
A new cytotoxic 25-membered macrolide, amphidinolide C2 (1), has been isolated from marine dinoflagellate Amphidinium sp. (Y-71 strain), and the structure 1 was elucidated on the basis of spectroscopic data and chemical means. 相似文献
57.
Ground-dwelling beetle community in beech forests of Sado Island,Japan: comparison with the mainland
Island ecosystems differ from mainland ecosystems in their long-term isolation. On Sado Island, Japan, cattle grazing in the
past gradually changed forests into grasslands, thereby altering the diversity of indigenous insects. We compared ground-dwelling
beetle diversity on Sado Island to that on the nearby mainland. Contrary to previous reports, the island isolation effect
resulted in lower γ and β diversity than on the mainland, because of the low species richness of beetles with low dispersal
abilities. Few flightless beetles could invade Sado Island, even when the beech forests on the island were relatively adjacent
to those on the mainland. Such a history of ecosystem formation could be the general pattern for continental-island mountain
forests that were never connected to those of the mainland. We did not observe low α diversity of ground-dwelling beetles,
suggesting that the cattle grazing history of the island has not changed environmental conditions for ground-dwelling beetles
enough to reduce their diversity. In addition, cattle grazing increases the abundance of merdivorous insects by increasing
the abundance of their food resource.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
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