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| Effects of biochar on butachlor adsorption isotherm and mechanisms in different soils |
| Received:November 21, 2023 |
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| KeyWord:soil;biochar;butachlor;adsorption isotherm;factor |
| Author Name | Affiliation | E-mail | | LI Xiang | Key Laboratory of Plant Nutrition and Fertilizer in South Region, Ministry of Agriculture and Rural Affairs Guangdong Key Laboratory of Nutrient Cycling and Farmland Conservation, Institute of Agricultural Resources and Environment, Guangdong Academy of Agricultural Sciences, Guangzhou 510640, China | | | ZHANG Chun | Guangdong Provincial Key Laboratory of High Technology for Plant Protection, Plant Protection Research Institute, Guangdong Academy of Agricultural Sciences, Guangzhou 510640, China | | | DENG Jianyun | Longmen County Agricultural Science Research Institute, Huizhou 516000, China | | | XU Guilian | Longmen County Rural Revitalization Service Center, Huizhou 516000, China | | | WEI Mulian | Foshan Agricultural Science Research Institute, Foshan 528145, China | | | WEI Lan | Key Laboratory of Plant Nutrition and Fertilizer in South Region, Ministry of Agriculture and Rural Affairs Guangdong Key Laboratory of Nutrient Cycling and Farmland Conservation, Institute of Agricultural Resources and Environment, Guangdong Academy of Agricultural Sciences, Guangzhou 510640, China | | | LIU Zhongzhen | Key Laboratory of Plant Nutrition and Fertilizer in South Region, Ministry of Agriculture and Rural Affairs Guangdong Key Laboratory of Nutrient Cycling and Farmland Conservation, Institute of Agricultural Resources and Environment, Guangdong Academy of Agricultural Sciences, Guangzhou 510640, China | lzzgz2001@163.com |
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| Abstract: |
| This study utilized nine different types of soils with varying physicochemical properties, to which a range of rice husk biochar dosages were added. We investigated the isothermal adsorption characteristics of butachlor in the biochar-soil mixtures, analyzing correlation between soil physicochemical properties and the effects of biochar addition. The results indicated that the adsorption isotherms of butachlor in the biochar-soil composites conformed to the Freundlich adsorption model. The addition of biochar significantly enhanced the adsorption capacity of the nine zonal soils for butachlor（increased adsorption coefficient Kf values）and reduced the degree of linear adsorption（decreased 1/n values）. After biochar supplementation, the adsorption capacity for butachlor was significantly increased. Thermodynamic calculations showed that the Gibbs free energy of butachlor in the nine soils ranged from -16.30 kJ·mol-1 to -21.67 kJ· mol-1 after biochar addition, suggesting that the adsorption process was spontaneous and favorable. Pearson correlation analysis revealed a significant negative correlation between soil organic carbon content and amorphous iron oxides with the rate of increase in, indicating that soil organic carbon and amorphous iron oxides inhibited the adsorption of butachlor by biochar. Multivariate linear regression analysis revealed that, without biochar, soil organic carbon content, pH, and clay, and silt levels accounted explained 99% of the the Kf value. However, when biochar addition was increased to 0.5%, 1%, and 2%, the explanatory power of these four soil physicochemical properties for the Kf value decreased to 83%, 70%, and 90%, respectively. This suggests that the introduction of biochar alters the adsorption mechanism of butachlor. Pathway analysis revealed that at 0 biochar addition, the direct effect coefficients of the four soil physicochemical properties were in the order of：soil organic carbon>sand>pH>clay, and at 1% biochar addition, the order was：clay>sand>soil organic matter>pH. The aforementioned results indicate that after the addition of biochar to soil, soil texture significantly influences the effectiveness of butachlor adsorption in soil. |
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