Dec. 2022, 乾燥地科学共同研究発表賞, Accuracy comparison between estimation models of drought stress index based on leaf temperature using stomatal conductance, Arid Land Research Center
Atsushi Sakaguchi

Oct. 2022, Prize of Japanese Society of Soil Physics, Hourly observation and modeling of relationship between dryness of soil and water stress of soybean measured by stomatal conductance at converted field, Japanese Society of Soil Physics
Atsushi SAKAGUCHI;Takuya TSUJI;Toshiki FUJII;Hideki ARAKI;Tadashi TAKAHASHI

Apr. 2014, 東京農工大学学生表彰, 東京農工大学
坂口敦
Others

Oct. 2013, 日本土壌肥料学会論文賞, 日本土壌肥料学会
坂口敦;加藤英孝;家田浩之;中野恵子
Japan society

Simulation of rice paddy systems in SWAT: A review of previous applications and proposed SWAT+ rice paddy module
Philip W. Gassman; Jaehak Jeong; Julien Boulange; Balaji Narasimhan; Tasuku Kato; Hiroaki Somura; Hirozumi Watanabe; Sadao Eguchi; Yuanlai Cui; Atsushi Sakaguchi; Le Hoang Tu; Rui Jiang; Min-Kyeong Kim; Jeffrey G. Arnold; Wei Ouyang, International Journal of Agricultural and Biological Engineering (IJABE)
International Journal of Agricultural and Biological Engineering, 2022, [Reviewed]

Hourly observation and modeling of relationship between dryness of soil and water stress of soybean measured by stomatal conductance at converted field
Atsushi SAKAGUCHI; Takuya TSUJI; Toshiki FUJII; Hideki ARAKI; Tadashi TAKAHASHI, Lead
Journal of the Japanese Society of Soil Physics, Nov. 2021, [Reviewed]

Hourly observation and modeling of relationship between dryness of soil and water stress of soybean measured by stomatal conductance at converted field
Atsushi SAKAGUCHI; Takuya TSUJI; Toshiki FUJII; Hideki ARAKI; Tadashi TAKAHASHI, Lead
PAWEES 2021 INTERNATIONAL CONFERENCE, Oct. 2021, [Reviewed]

Future Prediction of Field Soil Moisture using ELPIS-JP
TSUJI Takuya; FUJII Toshiki; SAKAGUCHI Atsushi, Corresponding
Journal of the Japanese Society of Soil Physics, Jul. 2020, [Reviewed]

HYDRUS-2Dを用いた野菜向け地下灌漑システムの設計手法
坂口敦; 佐々木英和; 柳井洋介, Lead, 畑地農業振興会
畑地農業, Feb. 2019

Subsurface irrigation system design for vegetable production using HYDRUS-2D
A. Sakaguchi; Y. Yanai; H. Sasaki, Lead, In the subsurface irrigation management of extensively cropped vegetables, uniform crop growth requires the maintenance of uniform soil water suction at the root zone across a field. Moreover, a fixed value of suction that is suitable for crop growth should be maintained. However, accounting for the temporal and spatial changes in the suction is beyond human capability. Using HYDRUS-2D, this study modeled a spinach field in Tsukuba, Japan, which is irrigated by subsurface irrigation pipes. The subsurface pipes were located 55 cm below the soil surface. The pipes were placed 150 cm apart. Belt-shaped water shielding sheets were installed beneath the pipes. Irrigation was empirically managed. The measured physical soil properties of the spinach field were input into the model as initial values and then calibrated using the irrigation data and observed soil water suction across the field. The calibrated model was further verified by comparing the simulated and other observed suctions. After model verification, several scenarios were created by varying the given conditions: (1) the intervals of subsurface irrigation pipes, (2) the depths at which the irrigation pipes were located, (3) the existence of a water shielding sheet beneath the irrigation pipes, and (4) the shape of the water shielding sheet. These scenarios were compared, and the optimal scenario, which facilitates equal soil water suction that is close to the suction required for the growth of spinach, was selected.
Agricultual Water Management, 2019, [Reviewed]

Chisel Plow Tillage as a Mitigation Technique of Wet Damage at Paddy Field without Underdrainage
SAKAGUCHI Atsushi, Lead
IRRIGATION, DRAINAGE AND RURAL ENGINEERING JOURNAL, Nov. 2018, [Reviewed]

Development and evaluation of a paddy module for improving hydrological simulation in SWAT
A. Sakaguchi; S. Eguchi; T. Kato; M. Kasuya; K. Ono; A. Miyata; N. Tase, Lead, The soil and water assessment tool (SWAT) is becoming a popular tool for modeling watershed-scale hydrological and chemical transport in Asia, where paddy rice is cultivated in typical agricultural management systems. In this study, a paddy module was developed by modifying an algorithm designed for pothole landscapes in SWAT. To simulate the percolation processes in paddy fields, a new parameter, the 'potential percolation rate of the paddy field,' was introduced which determines the upper limit of the rate of percolation into the subsoil. The potential percolation rate was calibrated to fit the observed flow rate of a stream. In addition, the ponding-releasing process was varied to simulate a winter paddy field. Moreover, the irrigation process was modified to avoid overflows from paddy fields during irrigation management. Furthermore, the evaporation process was modified in accordance with the evaporation rate observed at a paddy field. The developed paddy module was tested by applying it to a 3 km(2) watershed in which paddy fields comprise 18% of the total area. It was concluded that the water balance in the irrigated paddy fields was reasonably modeled by the modified SWAT with the developed paddy module and that the modified SWAT is effective for watershed-scale modeling for watersheds containing paddy fields. (c) 2014 Elsevier B.V. All rights reserved., ELSEVIER SCIENCE BV
AGRICULTURAL WATER MANAGEMENT, May 2014, [Reviewed]

Examination of the water balance of irrigated paddy fields in SWAT 2009 using the curve number procedure and the pothole module
Atsushi Sakaguchi; Sadao Eguchi; Masahiro Kasuya, Lead, The Soil and Water Assessment Tool (SWAT), a basin-scale hydrological and water quality simulation model, has become popular in Asia for assessing the impacts of land use and human activities including paddy rice (Oryza sativa L.) cultivation which is a typical agricultural management system in Asia. The water ponding and drainage management in paddy fields should significantly affect the regional hydrology and water quality; however, the suitability of SWAT for simulating paddy hydrology at a field scale has not been thoroughly examined.
In this study, the water balance of irrigated paddy fields in SWAT was examined for a small watershed where actual daily irrigation data were available. Two approaches available in SWAT to calculate hydrology in a watershed containing paddy fields, the curve number procedure and the pothole module, were applied with the regional paddy rice management standard.
The water balance components estimated using the pothole module were significantly different from the actual hydrology in paddy fields. The estimated percolation of water was zero on most days even under ponded water conditions. Any of the percolation, surface runoff and evapotranspiration (ET) was estimated to be zero during the drainage period. The estimated ET was too small on a number of days during the ponding period. As a result, the watershed-scale Nash-Sutcliffe model efficiency (NSE) for the daily river flow rate at the outlet of the watershed was less than zero, indicating low model efficiency. On the contrary, no significant problems were apparently found in the estimated water balance components in paddy fields using the curve number procedure, yielding a higher NSE value of 0.58 at the watershed scale. However, the curve number procedure that in principle cannot simulate the ponded water conditions is obviously impossible to use to reflect the various paddy water management scenarios in the field.
In conclusion, neither of these two approaches is suitable for simulating paddy field hydrology, indicating the need for the development of a paddy module in SWAT., TAYLOR & FRANCIS LTD
SOIL SCIENCE AND PLANT NUTRITION, 2014, [Reviewed]

P1-1-2 福島県内の異なる水田環境中における溶存態及び懸濁態放射性セシウム濃度の変動要因(ポスター,1-1 物質循環・動態,2013年度名古屋大会)
江口 定夫; 神山 和則; 藤原 英司; 山口 紀子; 藤村 恵人; 斎藤 隆; 吉川 省子; 板橋 直; 三島 慎一郎; 坂口 敦; 朝田 景; 坂西 研二; 木方 展冶; 井倉 将人, 一般社団法人 日本土壌肥料学会
日本土壌肥料学会講演要旨集, 2013

Development of rice paddy module for SWAT　　　　　　　　　　　　　　　
Sakaguchi A; Eguchi S; Kato T; Kasuya M, Lead
SWAT Conference in South East and East Asia, 2013, [Reviewed]

Rice paddy module development in SWAT　　　　　　　　　　　　　　　
Watanabe H; Boulange J; Eguchi S; Kato T; Sakaguchi A; Gassman PW
SWAT Conference in South East and East Asia, 2013, [Reviewed]

SWAT APPLICATIONS IN RICE PADDY WATERSHEDS　　　　　　　　　　　　　　　
Eguchi S; Sakaguchi A
The 2nd WASWAC World Conference, 2013

Estimating nitrate travel time to groundwater in agricultural areas in the Tone River basin from deep soil properties and layer characteristics
SAKAGUCHI Atsushi; KATOU Hidetaka; IEDA Hiroyuki; NAKANO Keiko, Lead, Travel time of leached nitrate arriving at the groundwater can vary greatly with soil, geographical, and meteorological characteristics of the agricultural area. Nitrate travel time to the groundwater was estimated over the agricultural area, excluding paddy fields, in the Tone River basin. For 213 points where the soil layering characteristics are known, the shallow groundwater level and the net annual water infiltration, calculated from annual precipitation and estimated potential evapotranspiration, were interpolated. Deep soil layers found in the basin were categorized into 15 groups, for each of which hydraulic properties were parameterized using van Genuchten's equation. The volumetric water content profile at each point was computed with numerical simulation software (HYDRUS-1D), assuming a steady downward water flux equivalent to the net annual infiltration. The retardation factor for nitrate was inferred by assuming that the maximum adsorption for nitrate was proportional to the adsorbed sulfate content in the soil layer. Travel times of water and nitrate down to the groundwater in the basin were interpolated from those predicted for the 213 points by assuming a piston-like displacement. The estimated travel time of nitrate ranged from 0.4 to 31 years. Longer travel times were obtained in the Gunma Prefecture and along the midstream of Kinu River, where the net water infiltration was small and a thick deposition of soil layers with a high volumetric water content and a large retardation factor was found. Travel times were shorter in the western foothills of the Tochigi Prefecture, owing to the greater net water infiltration and shallower groundwater level. Short travel times found in the midstream and downstream regions of the Tone River were associated with the presence of impervious Joso clay layer, which causes the horizontal subsurface flow observed in the region. These results suggest that in different regions of the basin, it takes different times for changes in soil and fertilizer management to be reflected in the shallow groundwater quality. These differences should be taken into account in evaluating the effectiveness of agronomic practices aiming at the improvement of environmental quality., Japanese Society of Soil Science and Plant Nutrition
Japanese Journal of Soil Science and Plant Nutrition, 2013, [Reviewed]

SWATモデルの水田を含む流域への適用の問題点と改善に向けて
加藤亮; 渡邊裕純; Julien Boulange; 江口定夫; 坂口敦; 宗村広昭
農業農村工学会誌, 2013, [Reviewed]

Applying SWAT to a watershed containing paddy fields using a soil-profile physical properties dataset　　　　　　　　　　　　　　　
Sakaguchi A; Eguchi S; Kasuya M, Lead
2012 International SWAT Conference, 2012, [Reviewed]

Verification and modification of SWAT for modeling hydrological processes in a watershed containing paddy fields　　　　　　　　　　　　　　　
Sakaguchi A; Eguchi S; Kato T; Kasuya M, Lead
MARCO Symposium 2012, 2012, [Reviewed]

Behavior of radiocaesium in soil-plant systems and its controlling factor
山口紀子; 高田裕介; 林健太郎; 石川覚; 倉俣正人; 江口定夫; 吉川省子; 坂口敦; 朝田景; 和穎朗太; 牧野知之; 赤羽幾子; 平館俊太郎, Radionuclides released from the Fukushima Daiichi Nuclear Power Plant of Tokyo Electric Power Company widely spread to the environment and severely damaged Japanese agricultural sector. Radiation exposure likely continues for a long time due mainly to radioactive caesium which has long half-life(^<134>Cs: 2.06 y, ^<137>Cs: 30.2 y). Once deposited to soil, radioacitive caesium first adsorbs on soil surfaces and a fraction of the adsorbed caesium dissolves into soil solution. The dissolved caesium transfers to plants via root uptake and some of it translocate to edible parts of the plants. Only a minuscule fraction of adsorbed caesium dissolves into soil solution because of strong affinity of radioactive caesium ion to soil particles. The strong affinity of caesium with soil minimizes the radioactive contamination of agricultural products, however effective removal of radioactive caesium from soil is difficult. In forest and other semi-natural ecosystems, large fractions of radioactive caesium are present in relatively mobile forms due to active biological recycling. The mobile caesium in forests can transfer into nearby agricultural lands via fluvial processes. It is therefore necessary to account for the dynamics of radioactive caesium at watershed scale. In this article, we review the behavior of radioactive caesium in agricultural ecosystem and other plant-soil systems as well as its controlling factors. In addition, we summarize the potentially-viable techniques for the removal of radionuclides in agricultural lands and discuss the balance between effectiveness and possible(or potential) side-effects of each technique., 農業環境技術研究所
農業環境技術研究所報告, 2012, [Reviewed]

The effect of entrapped air on the quasi-saturated soil hydraulic conductivity and comparison with the unsaturated hydraulic conductivity
A Sakaguchi; T Nishimura; M Kato, Lead, Entrapped air can greatly affect the hydraulic conductivity at or near saturation. In this study, we measured the hydraulic conductivity and volume of entrapped air in a quasi-saturated soil. Two soils, a Masa sandy loam soil from weathered granite rock and a TUAT light clay andisol from volcanic ash, were used. The soils, with three different dry bulk densities, were packed into a steel cylinder. To attain complete saturation, the packed soil samples were immersed in a 0.02 mol L-1 gypsum solution under vacuum conditions. The soil samples were then left on a sintered porous plate with suction of -17.0 kPa for different periods of time to allow drainage and air intrusion. After this drainage process, the samples were again immersed in water to permit air entrapment. The hydraulic conductivity was measured using the falling head method, and the amount of entrapped air was determined gravimetrically. The quasi-saturated hydraulic conductivity was found to decrease with increasing entrapped air content until the soil the maximum fraction of entrapped air, approximately 10% of the bulk soil volume. A comparison of the quasi-saturated and unsaturated hydraulic conductivities of the soil samples at or near saturation, when the suction of soil water was greater than the air-entry value, showed that the quasi-saturated hydraulic conductivity was smaller than the unsaturated hydraulic conductivity., SOIL SCI SOC AMER
VADOSE ZONE JOURNAL, Feb. 2005, [Reviewed]

Temporal changes of soil oxygen concentration as an indicator of the wet damage　　　　　　　　　　　　　　　
Atsushi SAKAGUCHI
J. Jpn. Soc. Soil Phys., Mar. 2024, [Reviewed]
Lead

気孔コンダクタンスを利用した土壌水分過不足による作物の水ストレスの評価
坂口敦; 岩谷潔; 荒木英樹; 高橋肇
土壌の物理性, 2021

Evaluation of crop water stress using stomatal conductance under soil water deficit and excess condition
坂口敦; 岩谷潔; 荒木英樹; 高橋肇
土壌物理学会大会講演要旨集(Web), 2020

Examining soil parameters determination on an Andosol field by using DIDAS
柳井洋介; 栗山淳; 松永明子; 高橋徳; 坂口敦; 佐々木英和
土壌物理学会大会講演要旨集(Web), 2019

土壌特性・土層構成に基づく利根川流域内農耕地における硝酸イオンの地下水到達時間の面的推定(日本土壌肥料学雑誌論文賞,2014年度東京大会)
坂口 敦; 加藤 英孝; 家田 浩之; 中野 恵子
日本土壌肥料学会講演要旨集, 09 Sep. 2014

SWAT水田モジュールの開発
坂口敦; 坂口敦; 江口定夫; 加藤亮; 糟谷真宏
農業農村工学会大会講演会講演要旨集, 2013

1-10 土壌特性・土層構成に基づく硝酸イオンの地下水到達時間の面的予測(1.物質循環・動態,2007年度東京大会)
加藤 英孝; 坂口 敦; 家田 浩之; 中野 恵子
日本土壌肥料学会講演要旨集, 22 Aug. 2007

Development of irrigation management system using UAV based on CWSI and soil moisture estimation　　　　　　　　　　　　　　　
Atsushi SAKAGUCHI; Haruyuki FUJIMAKI
共同利用・共同研究拠点鳥取大学乾燥地研究センター令和6年度共同研究発表会, 08 Dec. 2024
20241207, 20241208

Monitoring of soil suction from leaf temperature using UAVs
Atsushi Sakaguchi
2023年度農業農村工学会土壌物理部会, 20 Oct. 2023, [Invited]
20231020, 20231020

Accuracy comparison between estimation models of drought stress index based on leaf temperature using stomatal conductance
Atsushi SAKAGUCHI; Haruyuki FUJIMAKI
共同利用・共同研究拠点鳥取大学乾燥地研究センター令和4年度共同研究発表会, 04 Dec. 2022
20221203, 20221204

Progress report on development of irrigation index mapping system by using UAV
Atsushi Sakaguchi; Chris Schelfhou; Haruyuki Fujimaki; Kadambot Siddique
2022年度土壌物理学会大会, 29 Oct. 2022
20221029, 20221029

Modeling of relationship between dryness of soil and water stress of soybean
Atsushi SAKAGUCHI; Takuya TSUJI; Toshiki FUJII; Hideki ARAKI; Tadashi TAKAHASHI
2021年度（第70回）農業農村工学会大会講演会, 01 Sep. 2021
20210831, 20210902

Evaluation of crop water stress using stomatal conductance under soil water deficit and excess condition　　　　　　　　　　　　　　　
Atsushi Sakaguchi
土壌物理学会, 31 Oct. 2020
20201031, 20201031

Designing subsurface irrigation system for vegetable production using HYDRUS-2D　　　　　　　　　　　　　　　
SAKAGUCHI Atsushi
Hydrus workshop, 20 Sep. 2018

Designing subsurface irrigation system for vegetable production using HYDRUS-2D　　　　　　　　　　　　　　　
SAKAGUCHI Atsushi
農業農村工学会, 05 Sep. 2018, [Invited]

堆肥の施用による土壌の物理性改善のメカニズム　　　　　　　　　　　　　　　
坂口 敦
農業農村工学会農地保全部会 第38回研究集会, 16 Nov. 2017

Mitigation of Wet Damage by Chisel Plow Tillage　　　　　　　　　　　　　　　
SAKAGUCHI Atsushi
土壌物理学会, 14 Oct. 2017

数値解析によるOPSISの設計と運用の最適化　　　　　　　　　　　　　　　
坂口 敦
園芸学会, 02 Sep. 2017, [Invited]

福島県内の異なる水田環境中における溶存態及び懸濁態放射性セシウム濃度の変動要因　　　　　　　　　　　　　　　
江口定夫; 吉川省子; 板橋直; 三島慎一郎; 坂口敦; 朝田景; 坂西研二; 木方展冶; 井倉将人; 神山和則; 藤原英司; 山口紀子; 藤村恵人; 斎藤隆
日本土壌肥料学会 2013年度名古屋大会, 2013, 日本土壌肥料学会

水田域での栄養塩類動態への適用をめざしたSWAT モデルの改良　　　　　　　　　　　　　　　
江口定夫; 坂口敦
第30回土・水研究会, 2013, 土・水研究会

SWAT水田モジュールの開発　　　　　　　　　　　　　　　
坂口敦; 江口定夫; 加藤亮; 糟谷真宏
農業農村工学会大会, 2013, 農業農村工学会

土壌特性・土層構成に基づく硝酸イオンの地下水到達時間の面的予測　　　　　　　　　　　　　　　
加藤英孝; 坂口敦; 家田浩之; 中野恵子
日本土壌肥料学会 2007年度東京大会, 2007, 日本土壌肥料学会

封入空気が土壌の透水性に与える影響　　　　　　　　　　　　　　　
坂口敦; 西村拓; 加藤誠
農業土木学会大会, 2003, 農業土木学会

封入不飽和土の透水係数の測定　　　　　　　　　　　　　　　
坂口敦; 西村拓; 加藤誠
土壌物理学会第44回シンポジウム, 2002, 土壌物理学会

Apr. 2024 - Present
茨城大学

Apr. 2024 - Present
茨城大学

Apr. 2024 - Present
茨城大学

Advanced Soil Physics　　　　　　　　　　　　　　　
Apr. 2023 - Present
Ibaraki University

土壌物理学実験　　　　　　　　　　　　　　　
Apr. 2023 - Present
Ibaraki University

土壌物理学　　　　　　　　　　　　　　　
Apr. 2023 - Present
Ibaraki University

多孔体物性学　　　　　　　　　　　　　　　
Apr. 2023 - Present
Ibaraki University

応用力学　　　　　　　　　　　　　　　
Apr. 2023 - Present
Ibaraki University

土壌物理学特論　　　　　　　　　　　　　　　
Apr. 2023 - Present
Ibaraki University

微積分学入門　　　　　　　　　　　　　　　
Apr. 2023 - Present
Ibaraki University

Apr. 2024 - Mar. 2025
茨城大学

山口大学

山口大学

山口大学

山口大学

Special Training in Professional English　　　　　　　　　　　　　　　
YAMAGUCHI UNIVERSITY

Experiments of Land Resource Sciences　　　　　　　　　　　　　　　
YAMAGUCHI UNIVERSITY

Special Lecture in RuralEnvironment and Information Science　　　　　　　　　　　　　　　
YAMAGUCHI UNIVERSITY

Fundamental Irrigation and Drainage　　　　　　　　　　　　　　　
YAMAGUCHI UNIVERSITY

Special Lecture of Biological and Environmental Sciences 2　　　　　　　　　　　　　　　
YAMAGUCHI UNIVERSITY

Special Seminar of Biological and Environmental Sciences　　　　　　　　　　　　　　　
YAMAGUCHI UNIVERSITY

Advanced Experiment of Biological and Environmental Sciences　　　　　　　　　　　　　　　
YAMAGUCHI UNIVERSITY

Land Resource Sciences　　　　　　　　　　　　　　　
YAMAGUCHI UNIVERSITY

Experiment on Hydraulic and Soil Environment　　　　　　　　　　　　　　　
YAMAGUCHI UNIVERSITY

Fundamental Surveying　　　　　　　　　　　　　　　
YAMAGUCHI UNIVERSITY

Science English　　　　　　　　　　　　　　　
YAMAGUCHI UNIVERSITY

Graduation Thesis　　　　　　　　　　　　　　　
YAMAGUCHI UNIVERSITY

Special Seminar　　　　　　　　　　　　　　　
YAMAGUCHI UNIVERSITY

山口大学

山口大学

山口大学

山口大学

山口大学

山口大学

山口大学

山口大学

山口大学

山口大学

Present, JAPANESE SOCIETY OF SOIL PHYSICS

Mar. 2025, JAPANESE SOCIETY OF SOIL SCIENCE AND PLANT NUTRITION

Mar. 2024, THE JAPANESE SOCIETY OF IRRIGATION, DRAINAGE AND RURAL ENGINEERING

霞ヶ浦流域の農業と水環境の調和促進研究プロジェクト　　　　　　　　　　　　　　　
Jan. 2024 - Mar. 2029

土壌水分と作物の水ストレスの関係の定式化と予測値の圃場整備における活用
若手研究
山口大学
Apr. 2021 - Mar. 2026

Development of irrigation management system by using UAV based on CWSI and soil moisture estimation of each field
一般研究
茨城大学
Apr. 2023 - Mar. 2025

畑作利用水田から河川への降雨流出および土壌と栄養塩流出の観測とモデル化　　　　　　　　　　　　　　　
山口大学
Apr. 2021 - Mar. 2024

Accuracy comparison between estimation models of drought stress index based on leaf temperature using stomatal conductance
一般研究
山口大学
Apr. 2021 - Mar. 2023

浅層暗渠圃場の排水過程のモデル化と暗渠設計の最適化　　　　　　　　　　　　　　　
山口大学
Apr. 2021 - Mar. 2022

気孔コンダクタンスを指標とした浅層暗渠の水ストレス緩和効果の評価　　　　　　　　　　　　　　　
山口大学
Apr. 2021 - Mar. 2022

基盤整備による土壌水分管理効果把握の研究業務　　　　　　　　　　　　　　　
受託研究
Apr. 2020 - Mar. 2021

売れる麦を核とする中山間水田輪作体系における収益力強化と省力化の実証　　　　　　　　　　　　　　　
Oct. 2016 - Sep. 2019

タンザニア水稲の水利用効率改善技術と農民間普及アプローチによる技術普及法開発　　　　　　　　　　　　　　　
Apr. 2016 - Mar. 2019