論文 - 森　也寸志

Effects of cellulose nanofibers on soil water retention and aggregate stability 査読

An Thuy Ngo, Yasushi Mori, Long Thanh Bui

Environmental Technology and Innovation   35   2024年8月

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担当区分：責任著者   掲載種別：研究論文（学術雑誌）  

Innovative solutions that address global challenges such as water scarcity and soil erosion are critical for maintaining sustainable agriculture. Due to their water-absorbing and soil-binding properties, cellulose nanofibers (CNF) can be applied to soil to enhance soil water retention and aggregate stability. In this study, we analyzed the effects of the drying temperature, dosage, irrigation water quality, and soil type on the efficacy of CNFs. Our results revealed that CNF dried at 5°C is more effective at absorbing water than others, and adding 1% CNF enhanced soil water content up to 98%. The CNF samples absorbed water due to their hydrophilic molecular groups and morphological structure, as confirmed by Fourier-transform infrared spectroscopy and scanning electron microscopy. CNF addition increased the soil volumetric water content and prolonged water retention by 22 days in the paddy soil samples, highlighting its potential for drought-prone areas. Furthermore, irrigation water quality, such as pH and cation values, influenced the interactions between CNF and water molecules, suggesting adjustments to the water retention curve. In its hydrated state, CNF promotes colloid flocculation and binds to soil particles, thereby strengthening the bonds crucial for aggregate formation and stability. CNF enhanced macro-aggregate formation by up to 48% and 59% in the masa and paddy soil samples, respectively. Our study emphasizes the potential of CNF for water conservation, soil health, and overall agricultural sustainability.

DOI： 10.1016/j.eti.2024.103650

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Heat-Induced alterations in water repellency of tropical and temperate Soils: A laboratory experiment using Ultisols and Andosols 査読

H. T.M. Perera, D. A.L. Leelamanie, Yasushi Mori, Morihiro Maeda

Catena   243   2024年8月

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掲載種別：研究論文（学術雑誌）  

Water repellency (WR) is commonly reported in soils covered with several plant species that are rich in waxes/resins, including Pinus caribaea (PIN) and Cryptomeria japonica (CED). Due to waxy and resinous litter, these forests are highly prone to wildfires. The heat produced during wildfires alters soil WR, and these alterations may vary between tropical and temperate soils and between soil separates (SS; soil particles ≤ 2 mm) and aggregates (AG; naturally available aggregates; d = 3–5 mm). This study aims to investigate the heat-induced changes in WR of SS and AG in tropical and temperate soils. The SS and AG obtained from four different depths (0–5, 5–10, 10–15, 15–20 cm) in a PIN forest in Sri Lanka (tropical) (PINSS, PINAG) and a CED forest in Japan (temperate) (CEDSS, CEDAG) were heated to 7 heating temperatures (TH) (50, 100, 150, 200, 250, 300, 350 °C) with 2 exposure durations (DE) (1 h, 2 h). The WR were measured using the molarity of an ethanol droplet test and water drop penetration time test. The WR in PINSS and PINAG increased with increasing TH up to 100–150 °C and decreased to be non-repellent with further heating, while that of CEDSS and CEDAG progressively decreased to be non-repellent with heating. Both soil types were non-repellent at higher TH levels (≥250 °C), and 0–5 and 5–10 cm layers became non-repellent at 150–250 °C, while 10–15 and 15–20 cm layers became non-repellent at 50–150 °C. Compared to TH, DE did not significantly alter WR. The WR in two soils showed different responses to heat, especially at lower TH levels. In AG and SS, the degree of WR altered with heating similarly, while persistence (how long soil remains water-repellent) altered differently in both soil types. Research on organic matter composition and soil mineralogy may provide future insights into heat-induced alterations in WR of tested soils.

DOI： 10.1016/j.catena.2024.108230

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Microbial community shifts indicate recovery of soil physical properties in a post-tin-mining area on Belitung Island, Indonesia 査読

Hirmas Fuady Putra, Long Thanh Bui, Yasushi Mori

Land Degradation and Development   35 ( 7 )   2395 - 2408   2024年4月

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担当区分：責任著者   掲載種別：研究論文（学術雑誌）  

Mineral mining often results in changes to the soil environment, reducing the sustainability of the surrounding environment. Restoring the physical and chemical properties of soil in post-tin-mining areas on the tropical island of Belitung, Indonesia, has been a laborious process after more than 10 decades of land reclamation. We aimed to determine which parameter of the soil properties was responsible for the slow recovery process and if there were other properties that indicated more rapid changes. We measured the physical, chemical, and biological properties of soils of different periods in the post-tin-mining areas. We sampled soil from three areas: 0, 1, and 6 years after mining and an adjacent natural forest as a reference site. The soil water content, hydraulic conductivity, bulk density, particle distribution, mineral content, and soil microbial composition were measured in the field and analyzed in the laboratory. The soil showed a fine particle loss and despite the absence of clay, water-holding capacity was significantly increased in the 6-year-old soil. Organic carbon increased by 0.2% after 6 years of reclamation. Copper, iron, manganese, and zinc in the soils fluctuated less. Minimal amounts of Pb and Cd were found. Soil bacterial communities shift with land age. Actinobacteria were dominant a few years after mining, while Proteobacteria colonized the mined area after 6 years. This study examined the more profound changes in the soil properties of tropical post-tin-mined land. Soil and bacterial characteristics can be used as markers to monitor the progress of land rehabilitation.

DOI： 10.1002/ldr.5068

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Heat-induced alterations in moisture-dependent repellency of water-repellent forest soils: A laboratory approach with Japanese Andosols 査読

H. T.M. Perera, Yasushi Mori, Morihiro Maeda, D. A.L. Leelamanie

Journal of Hydrology and Hydromechanics   72 ( 1 )   25 - 33   2024年3月

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掲載種別：研究論文（学術雑誌）  

Soil water repellency (SWR) is a phenomenon that prevents the spontaneous wetting of numerous forest soils. It is a moisture-dependent characteristic, which disappears when soil moisture reaches near saturation. The heat generated during forest fires affects soil characteristics including SWR. The possibility of heat influencing moisture-dependent repellency (MDR) is not well understood. The present study aimed to investigate the effects of different heating temperatures (HT) and exposure durations (ED) on MDR using water-repellent Japanese Cedar (CED) and Japanese Cypress (CYP) forest soils. Soil samples collected from 0–5 cm depth were exposed to heat separately at 50, 100, and 150 °C (HT) for 1 h and 2 h durations (ED). The MDR of heated and non-heated soils was determined using the water drop penetration time (WDPT) test in a drying process. During the drying process of the tested soils, SWR appeared and then increased with drying to reach an extreme level (WDPT ≥3600 s) that persisted for a range of decreasing moisture contents, and declined to be non-repellent again (WDPT = 0 s). The critical moisture content at which soils become water-repellent with drying (CMC), the highest and the lowest moisture contents when soils showed maximum SWR (HMCmax and LMCmax, respectively), and the integrated area below the MDR curve (SWR) decreased with increasing HT in both CED and CYP soils. The moisture content at which soils become non-repellent again during drying, MCNR, was independent of the type of soil and heat treatment. The range of moisture contents between HMCmax and LMCmax, where soils show maximum SWR during drying, decreased with increasing HT, from 50 to 150 °C in CED and from 100–150 °C in CYP. The SWR showed strong positive linear correlations with CMC and HMCmax. The heat generated during wildfires can alter the MDR and all the related repellency parameters of water-repellent forest soils. SWR prevails over a narrower range of moisture contents in heated soil compared with non-heated soils. Further investigations with higher temperature levels using different soil types would be important for a comprehensive understanding of the heat impacts on MDR.

DOI： 10.2478/johh-2023-0035

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Linear Macropore Installation to Reduce Red-Soil Erosion in Sugarcane Fields 査読

Eisei Morioka, Thanh Long Bui, Yasushi Mori, Kazutoshi Osawa, Akira Hoshikawa

Journal of Soil Science and Plant Nutrition   23 ( 3 )   4572 - 4582   2023年9月

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担当区分：責任著者   掲載種別：研究論文（学術雑誌）  

This study determines the cause of soil erosion in red soils in sugarcane fields, especially even with the use of subsoiling fissures, and to compare the effectiveness of a novel artificial linear-macropore with the insertion of fibrous material into the fractures. Four column treatments (tillage, subsoiling, linear-macropore with plant residue fillings, and no-tillage-with-mulching) were established. A subsoiler was used to break up hard soil layers to enhance infiltration, whereas mulching reduced the impact of raindrops on the soil. Sugarcane residue was inserted in the empty fissure to reinforce the structure, making linear macropore. Simulated rainfall with 20 mmh−1 was applied to the soil surface for 6 h per day for two days. Surface runoff, soil erosion, and drainage were measured during each run. Erosion was minimal (1/7 reduction), and bottom drainage was observed in the linear-macropore and no-tillage-with-mulching plots. Conversely, due to the formation of an impermeable layer or surface crust, high erosion (0.282 t-C ha−1 yr−1) and decreased drainage levels were detected in the subsoiling and tillage plots. Moreover, the aboveground protrusion of fibrous material at the linear-macropore maintained infiltration, even following crust formation. Field application of these four management strategies revealed the effectiveness of linear-macropore and mulching in reducing surface flow. Linear-macropore application maintains appropriate levels of infiltration, and insertion of plant residue fillings reinforces the macropore structure while also avoiding clogging. Hence, the linear-macropore scheme may represent an effective strategy for reducing surface runoff and red soil erosion.

DOI： 10.1007/s42729-023-01373-6

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Alterations in aggregate characteristics of thermally heated water-repellent soil aggregates under laboratory conditions 査読

H. T.M. Perera, D. A.L. Leelamanie, Morihiro Maeda, Yasushi Mori

Journal of Hydrology and Hydromechanics   71 ( 2 )   177 - 187   2023年6月

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掲載種別：研究論文（学術雑誌）  

The heat generated during wildfires modifies soil characteristics, including soil water repellency (SWR) and the water stability of aggregates, which are known to be interrelated. SWR lowers the rate of water entry into aggregates, minimizing aggregate disruption and subsequent erosion. This study aimed to examine these aggregate characteristics (SWR, water stability of aggregates) of thermally heated water-repellent soil aggregates under laboratory conditions. Water-repellent aggregates were collected from Eucalyptus grandis forest soil separately from four soil depths (0-5, 5-10, 10-15, and 15-20 cm) with varying initial repellency levels. Using an automated programmable muffle furnace, aggregates were separately exposed to three heating temperatures, TH (150, 200, 250 °C), three rates of heating (speed of rising temperature to reach relevant TH), RH (200, 400, 800 °C h-1), and three durations of exposure to relevant TH, ED (30, 60, 120 min). The molarity of an ethanol droplet test was used to measure the contact angle (contact angle>90°). The water drop penetration time (WDPT) was also measured. The SWR of aggregates declined with the increasing TH and ED. All aggregates were wettable once exposed to 250 °C. At the lowest TH and ED (150 °C, 30 min), the contact angle was <90° only in the least repellent aggregates collected from 10-15 and 15-20 cm depths. Although RH indicated the least influence on the measured parameters, the slowest RH (200 °C h-1) caused a comparatively greater decline in SWR. Water stability of aggregates increased with heating irrespective of decreasing SWR. Further investigations on heat-induced changes in organic compounds at molecular levels would be necessary to understand the theories for the behavior of aggregates.

DOI： 10.2478/johh-2023-0009

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Artificial macropores and water management effects on reduction of greenhouse gas emissions from rice paddy fields 査読

Thanh Long Bui, Yasushi Mori, Morihiro Maeda, Hiroaki Somura

Environmental Challenges   9   2022年12月

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担当区分：責任著者   掲載種別：研究論文（学術雑誌）  

Rice production is an important sector of global agriculture, sustaining more than half of the world's population. However, rice production contributes significantly to global warming through increased emission of greenhouse gasses (GHGs), primarily CH4, into the atmosphere. Therefore, this study examined countermeasures to reduce GHG emissions from paddy fields without affecting rice production. A column experiment was conducted to investigate the effects of soil macroporous structure and water management on GHG emissions from flooded alluvial clay soil (paddy soil). The soils were subjected to different management regimes: with and without artificial macropores, compost, and drainage treatment. Drainage was maintained at 6.5 mm d −1 to ensure infiltration yet prevent excessive leakage from the paddy field. The measured parameters included GHG emissions, soil water content, redox potential, soil temperature, soil swelling, total carbon, total nitrogen, iron, and manganese. The results showed that the soil column with macropores and drainage had significantly lower CO2 and CH4 emissions than that without macropores and drainage. In addition, the soil level increment, and thus, the amount of gas (CH4) produced in the soil column with drainage were lower than that without drainage. The combination of drainage treatment and macropores might have effectively acted as a hydrodynamic gradient and a structure that promotes freshwater intrusion into deeper soil profiles, inhibiting absolute anaerobic methanogenic activity. The redox potential of the column with drainage and macropores was the highest. Moreover, CO2 and CH4 emissions were reduced at a relatively small drainage rate of 6.5 mm d −1 by adding macropores to the soil. The findings confirmed that GHG emissions were effectively reduced by a porous soil structure at a low drainage rate. Macropore application also exhibited effectiveness at mitigating nutrient loss (TOC and TN) through the drainage. Therefore, low tillage before flooding would be preferable to conserve the macroporous structure. However, the results also highlight an adverse effect on mineral leaching (particularly Mn) through the column with macropores.

DOI： 10.1016/j.envc.2022.100657

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不耕起栽培と人工マクロポア導入が石垣島サトウキビ畑における土壌保水と有機物蓄積へ与える効果 査読

岡 香菜子, Thanh Long BUI, 森 也寸志, 大澤 和敏, 干川 明

土壌の物理性   150   93 - 103   2022年4月

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担当区分：責任著者   記述言語：日本語   掲載種別：研究論文（学術雑誌）  

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Macropore structure and water management affect greenhouse gas emissions in agricultural fields. Paddy and Water Environment.

Bui, T. L., Mori, Y., Yamamoto, Y., & Maeda, M

Paddy and Water Environment   2021年7月

Macropore structure and water management affect greenhouse gas emissions in agricultural fields. 査読

Bui, T. L, Mori, Y, Yamamoto, Y, Maeda, M

Paddy and Water Environment.   19   661 - 672   2021年7月

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担当区分：責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）  

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Pinhole multistep centrifuge outflow method for estimating unsaturated hydraulic properties with small volume soil samples.

Bui, L. T., & Mori, Y.

Water 2021   2021年4月

Pinhole multistep centrifuge outflow method for estimating unsaturated hydraulic properties with small volume soil samples. 査読

Bui, T. L, Mori, Y

Water (Switzerland)   13 ( 9 )   1169   2021年4月

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担当区分：責任著者   記述言語：英語  

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Organic Matter Clogging Results in Undeveloped Hardpan and Soil Mineral Leakage in the Rice Terraces in the Philippine Cordilleras 査読

Tomoyo Kurozumi, Yasushi Mori, Hiroaki Somura, Milagros O-How

Water (Switzerland)   12 ( 11 )   3158 - 3158   2020年11月

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担当区分：責任著者   掲載種別：研究論文（学術雑誌）   出版者・発行元：MDPI AG  

Rice terraces in Cordillera, Philippines, a world cultural heritage site, are threatened by the risk of collapse. It is crucial to manage these rice terraces for their conservation, while simultaneously practicing traditional farming. We examined the soil environment and investigated its effects on rice terrace conservation, by focusing on the hardpan condition; infiltration process, which is related to the collapse of rice terraces; and soil nutrition conditions in these sites. Field survey and soil analysis revealed that in areas where the hardpan was not sufficiently developed and water infiltration was effectively suppressed, organic matter content was significantly high, suggesting organic matter clogging. In these rice terraces, the amounts of P, K, Ca, and Mn were significantly low, showing the mineral leaching under reductive soil conditions. Therefore, hardpan formation, rather than organic matter clogging, is essential for the suppression of infiltration and prevention of potential terrace collapse. Because hardpan formation or organic matter clogging cannot be identified from the surface of flooded rice paddies, it is difficult to identify the influencing factor. Thus, we suggest that the hard soil layer should be checked before the planting season and drainage is allowed after the cropping season in the rainy season.

DOI： 10.3390/w12113158

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EVALUATION OF DRAINAGE PROCESS IN VINEYARD TO OBTAIN BETTER QUALITY OF WINE GRAPE

Yasushi Mori, Toshiko Miura, Thanh Long Bui

Application of Advanced Technologies in Agriculture   2020年10月

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担当区分：筆頭著者   記述言語：英語   掲載種別：研究論文（学術雑誌）  

Evaluation of Drainage Process in Vineyard to Obtain Better Quality of Wine Grape 査読

Yasushi Mori, Toshiko Miura, Bui Thanh Long

Application of Advanced Technologies in Agriculture   6   2020年10月

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担当区分：筆頭著者   記述言語：英語  

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大阪府における醸造用ブドウ園土壌の理化学性と果実品質との関係

三浦季子,佐野修司,三輪由佳,谷本秀夫,森也寸志

日本土壌肥料学雑誌   2020年

大阪府における醸造用ブドウ園土壌の理化学性と果実品質との関係 査読

三浦季子, 佐野修司, 三輪由佳, 谷本秀夫, 森也寸志

日本土壌肥料学会誌   91 ( 6 )   445 - 450   2020年

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記述言語：日本語  

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When do rice terraces become rice terraces? 査読

Yasushi Mori, Masaya Sasaki, Eisei Morioka, Kumiko Tsujimoto

Paddy and Water Environment   17   323 - 330   2019年7月

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担当区分：筆頭著者   記述言語：英語   掲載種別：研究論文（学術雑誌）  

© 2019, The International Society of Paddy and Water Environment Engineering. Rice terraces located on sloped hills in mountainous areas are sometimes abandoned because of lack of labor and difficulties associated with cultivation. Recently, rice terraces also have been re-evaluated from the perspectives of water conservation or flood control. As a consequence, restoration has been conducted in many locations. In this study, we conducted field research on rice terraces in Okayama in order to determine when rice terraces become stable as rice terraces. Soil samples were obtained from depths of 0, 10, and 30 cm in abandoned fields and rice terraces restored in 2015, 2016, and 2017. The results showed that total carbon was the highest in abandoned fields and gradually decreased in the 2017-restored fields, followed by that in the 2016-restored fields. Particle analysis, particularly of surface soil, showed that the sand fraction decreased in order of abandoned fields, 2017-restored fields, and 2016-restored fields. We established that recently restored rice terraces have similar properties to those located on mountain hills, including few fine particles and high organic matter content in the surface soils. If the surface soil was cultivated and mixed with deeper soils, then the clay and silt content would gradually increase with time. Cone penetrometer analysis revealed that there was no clear evidence of a hard pan in the abandoned field and the 2017-restored field. In contrast, a hard pan had begun to develop in the 2016-restored fields and that it had become well established in the 2015-restored fields. Collectively, our findings indicate that although all rice terraces have a superficially similar appearance, recently recovered fields tend to have properties comparable to the properties of those located on mountain hills. These properties gradually change in the 2–3 years following restoration with the subsequent development of a well-established hard pan. We conclude that even rice terraces that have been abandoned for more than 30 years can develop clear properties of rice terraces within 3 years after restoration.

DOI： 10.1007/s10333-019-00727-0

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Impacts of Hydrological Changes on Nutrient Transport From Diffuse Sources in a Rural River Basin, Western Japan 査読

Jun'ichiro Ide, Ikuo Takeda, Hiroaki Somura, Yasushi Mori, Yuji Sakuno, Yasumichi Yone, Erina Takahashi

Journal of Geophysical Research: Biogeosciences   124 ( 8 )   2565 - 2581   2019年1月

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

©2019. American Geophysical Union. All Rights Reserved. Increased frequency of heavy rainfall caused by climate change may affect nutrient transport from forests and agricultural lands into downstream rivers. However, little information is available on how the effects of land cover on nutrient concentrations in the downstream rivers change depending on hydrological conditions. To elucidate this, we investigated the effects of changes in precipitation and river discharge on the relationship between river nutrient concentrations (total nitrogen, total phosphorus, nitrate, and phosphate) and land cover in eight subbasins of the Hii River basin, western Japan. We hypothesized that coniferous forests and agricultural lands including poorly managed ones, which require thinning and fertilizer management, respectively, contribute to increases in nutrient concentrations in downstream rivers during storms. Linear mixed-effects model analyses based on 18-year observation data were used for testing the hypothesis. Results revealed that the slopes of the multiple regression analysis between nutrient concentrations and coniferous and broad-leaved forest area ratios were negative and decreased with increasing daily precipitation. This suggests that forests contributed to the dilution of river nutrient concentrations during storms regardless of whether they were coniferous or broad leaved. In contrast, the slope of regression between nutrient concentrations and agricultural area ratio revealed the opposite trend, indicating that even a small percentage of agricultural area makes a large contribution to increases in nutrient concentrations as precipitation increases. Our results imply that storm runoff in response to rainfall results in an elevated supply of nitrogen and phosphorus attached to arable soils to the river.

DOI： 10.1029/2018JG004513

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岡山県倉敷市におけるナゴヤダルマガエルの越冬環境 査読

多田 正和, 伊藤 邦夫, 齋藤 稔, 森 也寸志, 福桝 純平, 中田 和義

農業農村工学会論文集   87 ( 2 )   I_179 - I_187   2019年

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記述言語：日本語   出版者・発行元：公益社団法人 農業農村工学会  

&lt;p&gt;ナゴヤダルマガエルの越冬場所に影響を及ぼす環境要因の解明を目的として, 岡山県倉敷市内で本種が高密度に生息する地区の慣行水田と休耕田の各1筆で野外調査を実施した．その結果, 越冬個体の大半（35個体中34個体）が休耕田で確認された．越冬個体の在／不在（1／0）を目的変数, 各コドラートのカバー率・草高・土壌pH・体積含水率・間隙率・土壌硬度を説明変数として一般化線形モデル（GLM）により解析した結果, 土壌硬度・カバー率・草高の二乗項が最良モデルで選択され, 土壌硬度には有意な負の効果が認められた．水田で本種の越冬場所を創出する上では, 土壌硬度と田面の植物の存在が重要になると考えられた．&lt;/p&gt;

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