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Access type: UnknownAuthor: search.filters.author.Chaisarn, Sumetha

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    Combining compost and biochar facilitates moisture improvements and plant growth under field conditions
    (2026-03-01)
    Kamchoom, Viroon
    ;
    Chaisarn, Sumetha
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    Ni, Junjun
    ;
    Chen, Zhongkui
    ;
    Sinsamutpadung, Natdanai
    Aims: Using vegetation on degraded soils often faces difficulties due to poor nutrients and limited water retention. Soil amendments such as compost and biochar are therefore required. However, their combined effects on soil and plant development are complex, as intense rainfall and high temperatures in tropical conditions may accelerate amendment degradation and alter soil properties over time. Methods: A two-year field experiment was conducted to monitor soil moisture dynamics, microstructure, vetiver grass (Chrysopogon zizanioides) growth, including shoot height, root depth, and root biomass. Four treatments were compared: unamended soil (S), soil + compost (C), soil + compost + raw biochar (C + RB), and soil + compost + pre-treated biochar (C + PB). Results: S and C treatments exhibited relatively low water retention, associated with smaller proportions of sub-micropores and super-nanopores. C contained more large pores, promoting drainage but causing greater moisture fluctuations. In contrast, C + RB enhanced water retention by increasing fine-pore volumes, while C + PB achieved the highest and most stable soil water content. The improved moisture conditions in C + PB corresponded with deeper rooting and greater root biomass compared with other treatments. Conclusion: Pure compost promoted early plant growth but was less effective over multiple wet–dry seasons, as its organic matter decomposed rapidly under tropical conditions. Combining compost and biochar, particularly pre-treated biochar, offers a practical, field-ready approach to improve soil structure and moisture retention, thereby supporting sustained plant growth in degraded soils.
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    Sustainable Reduction of Soil Permeability through Microbial Bio-Clogging
    (2026-01-01)
    Kamchoom, Viroon
    ;
    Chaisarn, Sumetha
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    Khattiwong, Thiti
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    Laokhongthavorn, Laemthong
    Microbially induced bio-clogging presents a promising, sustainable alternative to conventional soil improvmeent methods for mitigating seepage in geotechnical applications. Despite its potential, uncertainties remain regarding the influence of bacterial concentration, culture medium application, and associated setting times under field-like conditions—factors which are critical to the effective deployment of this technology in practice. This study investigates the impact of bacterial bio-clogging on the hydraulic behaviour of coarse-grained soils, with particular emphasis on the system's performance during and following the cessation of culture medium supply. Laboratory experiments were conducted to assess the mechanisms of permeability reduction resulting from microbial colonisation and extracellular polymeric substance (EPS) production. Results demonstrate that bacterial adhesion and subsequent EPS accumulation lead to the progressive clogging of soil pores, causing a marked decline in saturated permeability. The observed reductions in permeability are comparable to those produced by traditional methods such as cement and bentonite grouting. This highlights the durability of the biofilm matrix and its ability to maintain hydraulic resistance in the absence of continued nutrient input. These findings contribute valuable insight into the viability of bio-clogging as a ground improvement strategy. By elucidating the relationship between bacterial activity, EPS production, and soil pore occlusion, this research advances the practical understanding required to optimise bio-mediated techniques for field-scale applications in sustainable geotechnical engineering.