Journal of the Japanese Society of Soil Physics

[title in Japanese]

[in Japanese]

2004 Volume 98 Pages 1-2
Published: 2004
Released on J-STAGE: October 01, 2021

DOIhttps://doi.org/10.34467/jssoilphysics.98.0_1

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Latent Heat Transfer in a Salt-affected Nonswelling Clay

Iwao Sakaguchi, Hidetoshi Mochizuki, Mitsuhiro Inoue, Shinobu Inanaga

2004 Volume 98 Pages 3-10
Published: 2004
Released on J-STAGE: October 01, 2021

DOIhttps://doi.org/10.34467/jssoilphysics.98.0_3

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Latent heat transfer (LHT) with phase-change from liquid to gas occurs, when there is a temperature gradient in the porous media. LHT is a characteristic of porous media like soils, but there are few studies on the relationship between LHT and solutes. Although Philip and de Vries model was often used to analyze LHT, solutes have never been taken into consideration in the model. In this study, LHT was analyzed theoretically and experimentally with an assumption that the effects of temperature and salt concentration on thermal conductivity are caused by LHT. Thermal conductivities of Kaolin were measured under several conditions of water content, NaCl concentration and temperature. The LHT component of thermal conductivity was separated from the apparent one according to its temperature dependence, and analyzed by the extended method of Hiraiwa and Kasubuchi to estimate the phenomenological coefficient which contains tortuosity factor. As a result, the phenomenological coefficient never exceeded unity even at the maximum. The coefficient was expected to show a constant value under the fixed water content. However, it decreased with NaCl concentration. Further research is required on the tortuosity factor and modification of Philip and de Vries model, or introduction of other coefficients into the model to deal with solutes.

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Analysis of Ground Freezing Process by Unfrozen Water Content Obtained from TDR Data in Hetao Irrigation District of China

麗萍王, Takeo Akae

2004 Volume 98 Pages 11-19
Published: 2004
Released on J-STAGE: October 01, 2021

DOIhttps://doi.org/10.34467/jssoilphysics.98.0_11

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In this paper, the ground temperatures and the unfrozen water contents estimated from Time Domain Reflectometry (TDR) measurements at experimental site A(cultivated land) and C (salinized land) , were applied to analyze the ground freezing in Hetao Irrigation District, Inner Mongolia of China. Based on the different transportation status of unfrozen water, the frozen soils were divided into extensively frozen and partially frozen layer. In extensively frozen layer the unfrozen water content is kept as constant without remarkable changes, whereas below this layer, the unfrozen water content changed abruptly, the layer is referred partially frozen layer. It is found the isotherms of —1.2 and — 2.1°C are the boundary temperatures between extensively and partially frozen layers at site A and C, respectively. The estimated unfrozen water content showed the partially frozen layers still existed in the depth of 0.70〜0.90 m at the end of April.

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Practical Aspects of TDR for Simultaneous Measurements of Water and Solute in a Dune Sand Field

Hossein Dehghanisanij, Tahei Yamamoto, Mitsuhiro Inoue

2004 Volume 98 Pages 21-30
Published: 2004
Released on J-STAGE: October 01, 2021

DOIhttps://doi.org/10.34467/jssoilphysics.98.0_21

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Simultaneous measurement of volumetric soil water content (θw) and soil solution electrical conductivity (ECw) was made for dune sand soil using Time Domain Reflectometry (TDR). The best relationship between TDR dielectric constant (Ka) and Ow, and that for bulk soil electrical conductivity (ECb) and ECw were defined for dune sand soil and assessed in a dune sand field. The salinity of soil solution showed no effect on Ka and consequent θw. The commonly used linear relation between TDR transmission coefficient (T) and 6w was inaccurate for dune sand soil when θw was in the range of soil water holding capacity. A polynomial equation was suggested for expressing the relation between T and θw, with less variation than a power relation. Based on field assessment, there was a better agreement between θw)recorded by TDR and that from soil sampling than a similar relation for ECw. The relative error (RE) between TDR measured and soil sampling was 4.97% and 10.67% for Ow and ECw, respectively.

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Changes in the Water Holding Capacity of Abandoned Terrace Paddy Fields Following Afforestation

Yoshiki Shinomiya, Atsushi Torii, Yoshiyuki Inagaki, Tsuyoshi Yamada

2004 Volume 98 Pages 31-39
Published: 2004
Released on J-STAGE: October 02, 2021

DOIhttps://doi.org/10.34467/jssoilphysics.98.0_31

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Water holding capacity, soil physical properties and organic matter properties in abandoned terrace paddy fields were investigated in order to evaluate the effect of afforestation on water conservation function. We studied 12 abandoned terrace paddy fields where sugi (Cryptomeria japonica ) or hinoki {Chamaecyparis obtsusa) were planted. The stand ages ranged from 12 to 33 years. The water holding capacity and permeability of surface soil in abandoned terrace paddy fields increased with increasing stand age. They became almost equal to those in artificial forests of sugi or hinoki in mountainous area about 30 years after afforestation. The water holding capacity correlated with soil carbon content and can be predicted from the stand age and carbon content at the organic layer by multiple regression analysis. Increase of the stand age indicates increases of litterfall, carbon content in mineral soils and activity of soil fauna. As a result, soil aggregate develops well so that the water holding capacity increases. Comparing similarly aged stands, the water holding capacity and carbon content in mineral soils were greater in lower carbon content at organic layer. This suggests that decomposition of litterfall is important for the water holding capacity. These results suggest that water conservation function in soil of abandoned terrace paddy fields would be elevated following afforestation.

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[title in Japanese]

[in Japanese]

2004 Volume 98 Pages 41-42
Published: 2004
Released on J-STAGE: October 02, 2021

DOIhttps://doi.org/10.34467/jssoilphysics.98.0_41

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[title in Japanese]

[in Japanese]

2004 Volume 98 Pages 43
Published: 2004
Released on J-STAGE: October 02, 2021

DOIhttps://doi.org/10.34467/jssoilphysics.98.0_43

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[title in Japanese]

[in Japanese]

2004 Volume 98 Pages 44
Published: 2004
Released on J-STAGE: October 02, 2021

DOIhttps://doi.org/10.34467/jssoilphysics.98.0_44

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[title in Japanese]

2004 Volume 98 Pages 51-52
Published: 2004
Released on J-STAGE: October 02, 2021

DOIhttps://doi.org/10.34467/jssoilphysics.98.0_51

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[title in Japanese]

[in Japanese]

2004 Volume 98 Pages 53
Published: 2004
Released on J-STAGE: October 02, 2021

DOIhttps://doi.org/10.34467/jssoilphysics.98.0_53

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