Journal of the Japanese Society of Soil Physics

[title in Japanese]

[in Japanese]

2024 Volume 157 Pages 1-3
Published: July 20, 2024
Released on J-STAGE: August 19, 2024

DOIhttps://doi.org/10.34467/jssoilphysics.157.0_1

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The influence of soil dry bulk density and existence of soybean vegetation on greenhouse gases movement

Junko NISHIWAKI, Kaori KITAHARA, Toshihiro DOI, Tsuyoshi OKAYAMA

2024 Volume 157 Pages 5-17
Published: July 20, 2024
Released on J-STAGE: August 19, 2024

DOIhttps://doi.org/10.34467/jssoilphysics.157.0_5

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In this study, we investigated the production of CO2, CH4, and N2O gases in the soil and their emission into the atmosphere using an indoor pot experiment, focusing on the soil dry bulk density and the difference between soybean cultivation and non-cultivation. As a result of the experiment under three types of soil bulk densities, it was confirmed that the difference in water infiltration and evaporation in the pores due to the difference in dry bulk density caused differences in the distribution of soil water and nitrogen within the pot, causing the surface layer to become oxidized, producing CO2 and N2O, consuming CH4. As the depth increased, the amount of production and consumption decreased. Since this effect was large under the dry bulk density of 0.67 Mg m-3, it was thought that the magnitude of water movement, gas movement, and solute movement in pores were related. In addition, differences in the amount of infiltration water affected the movement of dissolved gases, and the movement of nitrogen, which is a substrate for gas production. This resulted in differences in gas concentration in the soil, which subsequently affected the gas flux and production amount. Effects of soybean were observed in the production of N2O and CO2 in the soil and the large sink of CO2 at the soil surface. Soybean cultivation was able to clearly reduce greenhouse gas emissions, but this was due to the dynamics of CO2.

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Estimating soil hydraulic and thermal properties using publicly available soil information for future prediction of soil temperature and water content

Juri ASANO, Yuki KOJIMA, Chihiro KATO, Kohji KAMIYA

2024 Volume 157 Pages 19-32
Published: July 20, 2024
Released on J-STAGE: August 19, 2024

DOIhttps://doi.org/10.34467/jssoilphysics.157.0_19

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Determining the soil hydraulic and thermal properties is necessary for computations in predicting the future soil temperature and water content. However, it requires a long time, enormous effort, and considerable expense, including soil sampling from the target site, laboratory testing, and optimization processing based on field observations. This study estimated soil hydraulic and thermal properties using publicly available soil information and pedotransfer functions, and examined their usefulness. Soil information was extracted from the Japanese Soil Inventory, and several pedotransfer functions were tested. The results of soil temperature and water content computations using the estimated soil hydraulic and thermal properties were compared with the computations using soil hydraulic and thermal obtained from previous studies. The estimation approach that minimized the error between the two was selected as the optimal approach. Then, the future soil temperature and water content were computed using the soil hydraulic and thermal properties obtained by the optimal estimation approach and compared with the results of previous studies. The predictions of volumetric water content and soil temperature differed due to the estimated soil hydraulic and thermal properties, but there was no significant difference in the amount of future change from the present to the future. This indicates that estimating soil hydraulic and thermal properties using publicly available soil information and pedotransfer functions may be acceptable if the estimation is limited to evaluating future changes.

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Development and evaluation of a soil gas measurement system for an artificial macropore

Application of the gas system to the shaft tillage method

Koharu TASAKI, Ieyasu TOKUMOTO, Shujiro KOMIYA, Kosuke NOBORIO

2024 Volume 157 Pages 33-42
Published: July 20, 2024
Released on J-STAGE: August 19, 2024

DOIhttps://doi.org/10.34467/jssoilphysics.157.0_33

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We developed a soil gas measurement system with a non-dispersive infrared CO2 sensor, a low-flow pump, and solenoid valves, designed to assess variations in soil CO2 concentrations within a macropore under specific cultivation conditions. The system's efficacy was evaluated through tests on the sensor's response to water vapor concentration, the system's airtightness, and the evaluation of CO2 concentrations in a macropore, using standard gases as references. The system is proved to be effective in monitoring soil gas concentrations within a macropore over a range of CO2 concentration from 400 to 7000 ppm and water vapor concentrations from 0 to 25 mmol mol-1. Further investigations were conducted using a soil column packed with Andisol, incorporating an artificial macropore beneath a young seedling with drip irrigation. Our findings suggest that CO2 gas emissions are influenced by preferential water flow, leading to increased water content at the macropore's bottom side, as determined by the water balance method.

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Solute transport with Ca2+ - Na+ exchange in soils

II. Effects of solute concentrations and compositions

Nobuo TORIDE, Koharu TASAKI, Kikuyo MIKUCHI, Ieyasu TOKUMOTO

2024 Volume 157 Pages 45-58
Published: July 20, 2024
Released on J-STAGE: August 19, 2024

DOIhttps://doi.org/10.34467/jssoilphysics.157.0_45

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Numerical simulations of solute transport with Ca2+ - Na+ exchange in soil under different solution concentrations and compositions of inflow and initial solutions were performed using the HP1 program (Hydrus1D-Phreeqc) under various solution concentrations and compositions. This research examined partial cation exchange, where only a portion of the exchangeable cations are replaced. When the Ca/Na mixture solutions flow through the soil, they reach equilibrium with the initial charge fraction of exchangeable cations at the midpoint of the concentration front, and no ion exchange occurs below this point. If the permeate concentration is lower than the initial solution concentration, a region emerges where the inflow concentration and a certain solution composition remain unchanged to maintain the initial exchangeable cation composition. In the lower regions, where the solution concentration approaches the initial solution concentration, ion exchange does not occur due to the balance between the effects of the total concentration and solution composition. However, even in the region where ion exchange does not occur, the transport of Ca2+ and Na+ is influenced by the cation-exchange property.

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[title in Japanese]

2024 Volume 157 Pages 59-60
Published: July 20, 2024
Released on J-STAGE: August 19, 2024

DOIhttps://doi.org/10.34467/jssoilphysics.157.0_59

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[title in Japanese]

[in Japanese]

2024 Volume 157 Pages 61-62
Published: July 20, 2024
Released on J-STAGE: August 19, 2024

DOIhttps://doi.org/10.34467/jssoilphysics.157.0_61

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[title in Japanese]

Chihiro KATO

2024 Volume 157 Pages 65
Published: July 20, 2024
Released on J-STAGE: August 19, 2024

DOIhttps://doi.org/10.34467/jssoilphysics.157.0_65

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