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| Competitive adsorption and desorption of glyphosate and phosphate on acid soil |
| Received:June 29, 2016 |
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| KeyWord:glyphosate;phosphate;competitive adsorption;disorption |
| Author Name | Affiliation | E-mail | | ZHOU Chui-fan | College of Forestry, Fujian Agriculture and Forestry University, Fuzhou 350002, China
Co-innovation center for soil and water conservation in red soil region of the Cross-straits, Fuzhou 350002, China | | | LIN Jing-wen | College of Forestry, Fujian Agriculture and Forestry University, Fuzhou 350002, China
Co-innovation center for soil and water conservation in red soil region of the Cross-straits, Fuzhou 350002, China | | | LI Ying | College of Forestry, Fujian Agriculture and Forestry University, Fuzhou 350002, China
Co-innovation center for soil and water conservation in red soil region of the Cross-straits, Fuzhou 350002, China | | | LIU Ai-qin | College of Forestry, Fujian Agriculture and Forestry University, Fuzhou 350002, China
Co-innovation center for soil and water conservation in red soil region of the Cross-straits, Fuzhou 350002, China | fjlaq@126.com |
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| Abstract: |
| The interaction of adsorption and desorption of glyphosate and phosphoate was investigated by conducting an isothermal adsorption-desorption experiment using red soil and yellow soil from Fujian Province. The results showed that the Langmuir equation best explained the phosphate adsorption behavior in red soil and yellow soil affected by glyphosate. Phosphate adsorption was a spontaneous endothermic reaction in both red soil and yellow soil, and the spontaneous tendency of glyphosate absorption was lower as the concentration of glyphosate increased. The phosphate adsorption quantity declined with increasing glyphosate levels in red and yellow soil. Compared to control, glyphosate inhibited desorption of high concentration phosphate. Moreover, the Freundlich and Langmuir adsorption isotherm equations explained the glyphosate adsorption process in both soils, and the Freundlich fitted better. In the absence of phosphate treatment, the adsorption of glyphosate in yellow soil was higher than red soil, but the adsorption quantity decreased with increasing concentration of phosphate in yellow soil. The glyphosate desorption quantity did not have noticeable regularity in red soil and yellow soil, and the desorption ratio declined, which was mainly influenced by adsorption quantity. However, with increasing phosphate concentration, desorption quantity of glyphosate decreased in red soil, and the desorption ratio also accordingly declined. Under different phosphate treatments, the variation of glyphosate desorption quantity ranged from 1.83~1.83 mmol·kg-1 in yellow soil, so phosphate did not strongly affect the desorption of glyphosate in yellow soil. Therefore, glyphosate and inorganic phosphate appear to compete for the same sorption sites, hence the applications of glyphosate and phosphorus may influence the bioavailability and transport potential of each other in the soil. |
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