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Article type: Cover
1998 Volume 42 Issue 1 Pages
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Article type: Cover
1998 Volume 42 Issue 1 Pages
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Article type: Appendix
1998 Volume 42 Issue 1 Pages
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Article type: Appendix
1998 Volume 42 Issue 1 Pages
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K. KIKUCHI
Article type: Article
1998 Volume 42 Issue 1 Pages
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Hirokatsu UTAGAWA, Shizuo NAGATSUKA, Hitoshi IKUZAWA
Article type: Article
1998 Volume 42 Issue 1 Pages
2-13
Published: June 30, 1998
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Genesis of Surface Gleyed Red-Yellow soils (Stagnic Acrisols, Epiaquic Paleudults) distributed widely on the hilly and Pleistocene terraces in the middle and northern part of Okinawa Island was studied from the viewpoint of the relationship between topographical distribution and physico-chemical properties of the soils. The results obtained are as follows: 1) The distribution of the sub-group of Surface Gleyed Red-Yellow soils (gRY) is closely related with the difference of microtopography. Surface Gleyed Red-Yellow soil (gRY_I) distributes on the relatively wide crest flat, whereas Surface Gleyed and Bleached Red-Yellow soil (gRY_<bI>) distributes on the slopes between crest flat and upper sideslope, and Podzol like Red-Yellow soil (P_D like) was found on the narrow crest flat and its shoulder slope. 2) The permeability coefficients of P_D like differ greatly between surface horizons (1.53×10^<-2> cm/sec.) and lower horizons (7.04×10^<-6> cm/sec.), and soil reaction of this type showed strong acid reaction. The permeability coefficients of gRY_I and gRY_<bI>, on the other hands, range from 4.73×10^<-2> to 8.86×10^<-4> cm/sec., and they showed relatively high positive correlation with the total porosity (r=0.89). The gRY_I showed weakly to slightly acid reaction, and gRY_<bI> showed strongly acid reaction. 3) From the relationship between topographical distribution and physico-chemical properties mentioned above, it is inferred that the genesis of each soil type is closely related with the frequency of soil water movement (the degree of the soil water effect) which derives from the difference of microtopography and soil permeability.
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Hirokatsu UTAGAWA, Shizuo NAGATSUKA
Article type: Article
1998 Volume 42 Issue 1 Pages
14-20
Published: June 30, 1998
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Seasonal changes of reduction-oxidation potential (redox-potential) in the surface horizon of Surface gleyed red-yellow soils (Stagnic Acrisols, Epiaquic Paleudults) in Okinawa Island were measured and its effect on the profile distiribution of free iron and aluminum oxides as well as exchangeable and easily reduciable manganese were analysed. The relations between the seazonal changes of redox-potential and the profile distribution pattern of the free iron, aluminum and manganese were different among the types of Suface gleyed red-yellow soils. From these facts the soil forming process of each types was deduced as follows: Surface gleyed red-yellow soil (gRY_I) distributed on the relatively wide crest flat has developed mainly by stagnogleization, whereas Surface gleyed and bleached red-yellow soil (gRY_<bI>) on the slopes between crest flat and upper sideslope has developed by the alternation of oxidative and reductive conditions (pseudogleization). On the other hand, Podozol like red-yellow soil (P_D like) on the narrow crest flat and it's shoulder is considered to thve developed by the combined soil forming process of reductive leaching and weak podzolization.
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Sohzoh SUZUKI, Hisako CHIYONOBU, Shinya AOIKE, Seiji KODATE, Yoshio IK ...
Article type: Article
1998 Volume 42 Issue 1 Pages
21-32
Published: June 30, 1998
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Changes of plant vegetation with years were observed in man-made forests formed by close planting of laurel nursery trees and in a natural forest. Ages of the man-made forests were lyear (ZR), 11 years (TN) and 18 years (TW) after planting trees and that of the natural forest (NF) was more than 100 years. 1) The height and structure of vegetation of TN and TW were 7. 5 to 10 m and 3 layers respectively and they were smaller than those of NF. 2) Though the numbers of trees per unit area in man-made forests were 2 to 4 times more than that of NF, the basal area (BA) and the D^2H of TN and TW were only 30% and 10% of NF by per tree respectively. 3) Number and D^2H of trees were occupied by a few kinds of dominant species in ZR, TN and NF in contrast with by several ones in TW. 4) Though the maximum frequency was 4-6 m in both TN and TW, TW also had the secondary maximum in 1.3-2 m. The frequency of NF decreased from gradually 30% in 1.3-2 m with increasing of heights. 5) Its is supposed that the man-made forests are on the way to a natural forest and they develop their vegetation with increasing stratification and/or biomass, e. g. D^2H in accordance with decreasing of numbers of trees by the natural selection.
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Sohzoh SUZUKI, Hisako CHIYONOBU, Shinya AOIKE, Seiji KODATE, Yoshio IK ...
Article type: Article
1998 Volume 42 Issue 1 Pages
33-43
Published: June 30, 1998
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Changes of soil profiele, soil physico-chemical properties and micro organism biomass with years were observed in man-made forests formed by close planting of nursery stocks of laurel trees and in a natural forest. Ages of the man-made forests were 1 year (ZR), 11 years (TN) and 18 years (TW) after planting trees respectively. Soil profiles showed the development of organic and humic layers with years as the increase of the depths of O and A horizon, darkness of soil colors, contents of roots and compactness. Though soil texture of man-made forest soils and a natural forest soil were loamy sand to sandy loam and clay loam respectively, it was difficult to recognize that soil texture changed for 10-20 years in man-made forest soils. Decreasing of bulk density and increasing of pore volume were observed with years except for some layers of TN. The starting depths of the constant lower values of softness decreased with years except TN and the values of softness in the subsoil of TN was lower than those of others. Total carbon, total nitrogen, CEC and microorganism biomass in soils increased with years and they were supposed to be caused from the increasing of plant residue with plant growth.
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Toru UTSUGAWA, Kiyoshi NAKAMURA
Article type: Article
1998 Volume 42 Issue 1 Pages
44-56
Published: June 30, 1998
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The results obtained were summarized as follows; (1) The fluvial terrace have developed in Kitakyusyu Regions. These terrace were- divided into three terrace groups, namely, the higher terrace surface, the upper terrace surface, and the lower terrace surface. The destribution of Red soil was restricted on relatively higher terrace surface. Red weathering crust covered with Aso-4 pyroclastic flow deposits distributed on the upper terrace surface. (2) The Aso-4 pyroclastic flow was one of the largest of activities of Aso volcano. (3) Aso-4 pyroclastic flow covered extensive area of Kyusyu round the Aso caldera and western part of Honsyu. (4) The ash, named the Aso-4 ash, was a fine-grained ash, consisting of bubble wall glass shard and brown hornblende, hyperthene and Magnetite. (5) Especially Aso-4 pyroclastic flow changes into the facies of white clay called as Yamenendo at its fill-top, and this is most extensively distributed as tephrochronological key bed in northern and middle Kyusyu. (6) The heavy mineral assemblage of Yamenendo was composed of brown hornblende, hyperthene, and augite. (7) The age of the upper terrace surface is at least older than 1.2-1.3×10^5 years.
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Yumei KANG, Toshihiko MIURA, Takashi KOSAKI
Article type: Article
1998 Volume 42 Issue 1 Pages
57-61
Published: June 30, 1998
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The influence of pH change on Cd leachability and chemical forms of contaminated soil was investigated. Results of sequential extraction of soil Cd showed that more than 70% of the total Cd in the contaminated soil was associated with the exchangeable, inorganically-bound and organically-bound fractions, suggesting that most of Cd are mobile in soil. As the pH of soils decreased, the water-soluble Cd contents increased remarkably. The increase of the water-soluble Cd was mainly from the exchangeable and inorganically-bound fractions, and also a part from the organically-bound, oxide-occluded and residual fractions. It was concluded when soil becomes acid, not only Cd in the fractions which equilibrated with solution desorpted, but also that some Cd dissolved from oxide-occluded and residual fractions, which must be released from the destruction of oxides and mineral.
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Yumei KANG, Toshihiko MIURA, Takashi KOSAKI
Article type: Article
1998 Volume 42 Issue 1 Pages
62-66
Published: June 30, 1998
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The effect of redox potential on Cd solubility and chemical forms in contaminated soil was investigated by incubation. As the incubation time elapsed, the Cd content in the submerged water decreased in accordance with lowering of soil Eh. This is considered to be attributable to the formation of cadmium sulfide. The decrease of the Cd content in submerged water was delayed for a few days from the decrease of Eh. This is because the formation of cadmium sulfide cannot occur until sulfate is reduced to sulfide by sulfatereducing bacteria. These results suggested that Cd changed into insoluble form in the order of mobility in soil. The exchangeable and inorganically-bound Cd shifted to the submerged water because the chemical equlibrium was broken by the precipitation of cadmium sulfide. The conclusion is that the insolubilizing of Cd in soil under incubation is a relatively slow process, but once the Cd dissolved into the solution, the formation of cadmium sulfide is extremely rapid.
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M. KAWATO
Article type: Article
1998 Volume 42 Issue 1 Pages
67-70
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Article type: Appendix
1998 Volume 42 Issue 1 Pages
71-85
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Article type: Appendix
1998 Volume 42 Issue 1 Pages
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Article type: Appendix
1998 Volume 42 Issue 1 Pages
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Article type: Appendix
1998 Volume 42 Issue 1 Pages
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Article type: Appendix
1998 Volume 42 Issue 1 Pages
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Article type: Cover
1998 Volume 42 Issue 1 Pages
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1998 Volume 42 Issue 1 Pages
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