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    Comparative study of nitrogen release from compound fertilizers in silty loam and sandy loam soils
    (2025-11-01)
    Preesong, J.
    ;
    Phromnak, P.
    ;
    Paenklang, F.
    ;
    Thammanatsakun, V.
    ;
    Yampracha, S.
    Most Thai farmers cultivate field crops on coarse-textured soils that are inherently low in fertility and highly susceptible to nutrient leaching, resulting in low nitrogen use efficiency. The results indicated that the Hin Kong (Hk) soil series exhibited greater ammonium-N and urea-N release than the Chanthuk (Cu) soil series, reaching 624 and 54.4 mg N kg<sup>-1</sup>, respectively. In contrast, the Cu soil series showed higher nitrate-N release, with 364 mg N kg<sup>-1</sup>. Among the fertilizer formulations, 15-7-18 produced the highest ammonium-N, urea-N, and available nitrogen release, although these values were not significantly different from those of the 15-5-20 formulation. Conversely, the 15-5-20 formulation generated the highest nitrate-N release (536 mg N kg<sup>-1</sup>), but its ammonium-N and available N release remained statistically comparable to the 15-7-18 formulation. The 15-7-18 fertilizer consistently promoted early-stage ammonium accumulation, reflecting its relatively ammonium-based composition, whereas the 15-5-20 formulation favoured rapid nitrate build-up in the Cu soil. The 16-8-8 formulation exhibited a more gradual release pattern in both soils, maintaining available N at later stages and suggesting slower transformation and solubilization rates compared with the other formulations. These findings indicate that nitrogen release dynamics are jointly governed by fertilizer formulation and soil properties—including not only soil texture but also organic matter content, cation exchange capacity, and soil acidity. Temporal patterns further revealed an initial rapid nitrogen release followed by stabilization, reflecting the combined effects of soil physical structure, chemical characteristics, microbial activity, and fertilizer traits. Selecting an appropriate fertilizer formulation is therefore essential for improving nitrogen use efficiency in coarse-textured soils.
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    Assessment and classification of different ashes from waste incinerators in Thailand
    (2024-12-01)
    Muthuraja, Raji
    ;
    Pombhejara, Chatpong Na
    ;
    Ganesan, Sunantha
    ;
    Attaphong, Chodchanok
    ;
    Morawan, Nattaya
    Rapid urbanisation and a growing population have led to a huge production of solid waste worldwide. To mitigate solid wastes, Thailand adapts incineration. As a consequence, a variety of fly ashes being produced in large quantities. Fly ash management is therefore a risk for the future. A comparison of the chemical and physical properties of five sources of ashes from the waste incinerators in three regions in Thailand, namely MFA1, MFA2, IFA, and fly ash that used in a ready-mixed concrete plant, CFA1 and CFA2 was conducted. Additionally, bottom ashes, MBA1, MBA2 and IBA were also characterized similarly. The analysis showed that coal fly ash from ready mixed concrete plant of CFA1 and CFA2 were classified under class F and C, respectively. The heavy metal analysis showed that fly ash from MFA1 and IFA has high amount of Zn (7,523 mg/kg and 28,315 mg/kg), followed by MFA1 has high amount of cadmium (127 mg/kg) and MFA1 and IFA showed high concentration of lead (1,955 mg/kg and 1,425 mg/kg). The present study show that fly ash often contains heavy metals, dioxins, and other hazardous substances, highlighting the need for detailed analysis to determine proper handling and disposal methods. Advanced classification systems, which may include parameters such as leaching behavior, particle size distribution, and contaminant concentrations, are essential for categorizing fly ash into appropriate management pathways, such as landfilling, resource recovery, or reuse in construction materials.
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    The effect of acid sulphuric soil restraint by groundwater control in nakhon-nayok province, THAILAND
    (2007-01-01)
    Seeboonruang, Uma
    ;
    Ichikawa, Tsutomu
    Nakhon Nayok Province, Thailand, is located in the floodplain area and has severe problems regarding acid soil which contains sulphide bearing material resulting in soil pH below 4.0. The objectives of this study are to investigate the geochemical variation that occurs under a groundwater controlling condition above the acid materials while other field factors are maintained in natural condition and to study the groundwater controlling technique to alleviate the acidic condition. The field experiment is designed in order to control groundwater level within a time period. The effects on the chemistry of groundwater, surface water, porewater and the soil itself are also monitored. The result rev-eals that acidity of the soil increases initially from the soil disturbance and the acidity decreases afterwards as a result of the groundwater controlling condition. This finding is also confirmed by the water chemical changes. Several cations are released into porewater when acidity increases and these metals can be hazardous to plants, foundations, and hu-mans. From this study, we conclude that soil disturbance from any activity can stimulate the acidity of the acid sul-phate soil, and maintaining groundwater level above the parent material can help alleviate the acidity.