Journal of the Japanese Society of Soil Physics
Online ISSN : 2435-2497
Print ISSN : 0387-6012
Volume 149
Displaying 1-14 of 14 articles from this issue
• YOSHIYUKI SHINOGI
2021 Volume 149 Pages 1-2
Published: 2021
Released on J-STAGE: January 20, 2022
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• Atsushi SAKAGUCHI, Takuya TSUJI, Toshiki FUJII, Hideki ARAKI, Tadashi ...
2021 Volume 149 Pages 3-12
Published: 2021
Released on J-STAGE: January 20, 2022
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We defined a water stress index which is a ratio of stomatal conductance of soybean between rain fed field and non-water stress field, and regressed the water stress index on soil moisture in the rain fed field. In addition, we applied a Jarvis model of soybean to estimate the stomatal conductance in the non-water stress field without measuring in the field. As a result, the stomatal conductance of both fields did not give significant difference in the morning, and correlation was not seen between the water stress index and the root zone suction in the rain fed field at 10 o'clock. On the other hand, the stomatal conductance gave significant difference in the afternoon, and the higher coefficient of determination was seen between the index and the suction at 13 o'clock when they were regressed by the equations of ellipse, the Feddes model and the S-shape model. We suppose the 13 o'clock would be the suitable time to model the transition of water stress in response to drying of soil. Regarding the Jarvis model, we found that the calibration for each time makes the value of coefficient of determination increase, although this is not reported in previous studies.
• Kotaro FUKADA, Masaki NAMBA, Yasutaka KIHARA
2021 Volume 149 Pages 13-21
Published: 2021
Released on J-STAGE: January 20, 2022
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An acoustic technique for evaluating soil physical properties, such as the air content and air permeability, uses sound waves reflected from the soil surface or penetrating sound waves in soil. It is difficult to set the measurement range in the soil depth because the propagation distance of a sound wave in soil depends on the soil physical properties to be measured. In this study, we compared the results of an acoustic resonance method for a sample whose bottom was open to the atmosphere with those for a sample whose bottom was closed. The propagation distance of the sound wave in soil was estimated from the length of the sample whose bottom condition had no effect on the results of the acoustic resonance method. We set the sample length smaller than the estimated propagation distance of a sound wave. The precision of the acoustic resonance method was then examined. We found that the propagation distance of a 5 -- 100 Hz sound wave in a decomposed granite soil sample was 3 -- 7.5 cm. The propagation distance was a maximum at volumetric air content of 20 %. Setting the sample depth to 1.3 cm and closing the sample bottom, the volumetric air content was determined with +0.9 % precision in a measurement range of 10 % --36 % whereas air permeability was determined with precision of + 0.05 cm s-1 in a measurement range of 0.05--0.65 cm s-1.
• Munehiro EBATO
2021 Volume 149 Pages 23-35
Published: 2021
Released on J-STAGE: January 20, 2022
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To promote the quantitative use of cone penetrometers, we analyzed patterns in the variation and distribution of penetration resistance data that were caused by differences in models and operators. Because of differences in the mechanism of pressure detection between models, the values of penetration resistance tend to be model-dependent around the boundary area above and below the plow pan. This prompted us to carry out data comparison between models. Nine operators surveyed 60 points each over the entire area of an 0.31-hectare field. The operators were two men and two women in their 40s, a man and two women in their 50s, and two women in their 60s. When weak women or elderly persons penetrated from the plow layer to the plow pan with the cone tip of the cone penetrometer more slowly than strong men, it appeared that the penetration resistance data around the boundary area above the plow pan could be collected more accurately. We conclude that the data necessary for creating three-dimensional distribution maps of soil hardness can be collected if the range of up to 3000 kPa of penetration resistance and 45 cm depth can be measured using a cone penetrometer, making it suitable as a machine setting.
• Chihiro KATO, Akira ENDO, Daiyu ITO, Sachinobu ISHIDA
2021 Volume 149 Pages 37-46
Published: 2021
Released on J-STAGE: January 20, 2022
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In this study, we conducted continuous monitoring of the soil moisture, temperature, and soil CO2 concentration at depths of 15 cm and 40 cm during the non-snowfall period, and the measurement of CO2 efflux from the soil surface in October in experimental greenhouses where apples were cultivated under the condition of elevated air temperature (+3 C) and atmospheric CO2 concentration (+0.02 %). The soil temperature at depth of 15 cm increased by approximately 3 ℃ accompanied by the rising air temperature. The soil CO2 concentration at depth of 15 cm and CO2 efflux from the soil surface was high in the order of (C) “elevated both air temperature and CO2 concentration” > (B) “elevated air temperature” > (A) “control” conditions. The CO2 efflux from the soil surface which was measured near an apple tree was larger than that away from a tree. The difference of the CO2 efflux from the soil surface among the three conditions ((A) ～ (C)) was more conspicuous when that was measured near a tree than away from a tree. In addition to elevated air temperature, high atmospheric CO2 concentration might result in increased biomass and both above- and under-ground dry matter weights of apple trees and undergrowth, thus accelerating the respiration rate or soil CO2 production rate of both plant roots and microorganisms.
• Ryunosuke TANIGAWARA, Yuki KOJIMA, Shoichiro HAMAMOTO, Kohji KAMIYA
2021 Volume 149 Pages 47-53
Published: 2021
Released on J-STAGE: January 20, 2022
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In recent years, the use of fine bubbles (FBs) has been studied as a remediation method for groundwater contamination by volatile pollutants, and the behavior of FBs in soil has been elucidated. In this context, in-situ measurements of FB concentration in water and soil are required. In this study, we focused on the FB concentration in water. We investigated the estimation of FB concentration using the time domain reflectometry (TDR), a widely accepted method for measuring soil moisture content. FBs were generated in distilled water and surfactant solution, and the change in relative permittivity was measured with three different size TDR probes. The TDR probes were placed horizontally or vertically upward in water. The results showed that the FB concentration in distilled water was difficult to estimate due to its low concentration, while the FB concentration in surfactant solution may be captured. Relatively large bubbles originating from FB adhered to the TDR probes, and it caused an underestimation of the relative permittivity. It was found that the effect of air bubbles could be reduced by installing a relatively large probe vertically upward. The dielectric mixing model may be appropriate for converting the relative permittivity to FB concentration. These results indicate that the TDR has the potential to easily and effectively estimate the FB concentration in-situ. Comparison between TDR-based FB concentration and that measured with other methods is necessary to evaluate the accuracy of the TDR approach. It is expected that the TDR will be used to estimate the FB concentration in soil in the future.
• Investigation of soil moisture and salinity at a tsunami-affected field in Miyagi
Yohei ISHIKAWA, Takuro NOGUCHI, Hideki MIYAMOTO, Ieyasu TOKUMOTO
2021 Volume 149 Pages 55-61
Published: 2021
Released on J-STAGE: January 20, 2022
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We developed a wireless communication network system with Arduino, XBee, and TDT sensors to investigate soil moisture and salinity. The sensor network system was installed to monitor soil moisture ($\theta$) and bulk soil electrical conductivity (ECb) at three locations in a soybean field converted from a paddy field of tsunami-damaged farmland, Miyagi. Measured data was available to download through a Web server. Our sensor network system allowed us to collect all data without power supply and communication problems after using sleep power-saving mode. Our finding was local spatial variability of high salinity, influencing soybean growth at the field.
• Yuta HIRASHIMA, Takahiro MAKI, Nobuhiro KOTODA, Ieyasu TOKUMOTO, Hidek ...
2021 Volume 149 Pages 63-68
Published: 2021
Released on J-STAGE: January 20, 2022
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• Kazushi TAKAKUSAGI, Yutaka KAIZU, Masaru MIZOGUCHI
2021 Volume 149 Pages 69-72
Published: 2021
Released on J-STAGE: January 20, 2022
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[in Japanese]
• Hirotaka SAITO, Chihiro KATO, Shoichiro HAMAMOTO, Yuki KOJIMA, Yasushi ...
2021 Volume 149 Pages 73-75
Published: 2021
Released on J-STAGE: January 20, 2022
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• Morihiro MAEDA, Tomohisa IRINO, Shin-Ichi ONODERA
2021 Volume 149 Pages 77-79
Published: 2021
Released on J-STAGE: January 20, 2022
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• [in Japanese]
2021 Volume 149 Pages 81-82
Published: 2021
Released on J-STAGE: January 20, 2022
JOURNAL FREE ACCESS