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Effect of liming on hexazinone sorption and desorption behavior in various soils

Dos Santos, Luiz Odonil Gomes, Souza, Matheus de Freitas, Das Chagas, Paulo Sergio Fernandes, Fernandes, Bruno Caio Chaves, Silva, Tatiane Severo, Dallabona Dombroski, Jeferson Luiz, Souza, Carolina Malala Martins, Silva, Daniel Valadão
Archiv für Acker- und Pflanzenbau und Bodenkunde 2019 v.65 no.9 pp. 1183-1195
alkaline soils, aluminum, calcium, clay fraction, desorption, groundwater contamination, hexazinone, leaching, limestone, liming, magnesium, neutralization, organic matter, preemergent weed control, soil pH, sorption, sorption isotherms, ultra-performance liquid chromatography
Liming is a practice commonly used to modify soil acidity, neutralize aluminum, and increase calcium and magnesium in the soil. Liming can change herbicide retention processes and consequently weed control and potential environmental contamination. The effects of liming on the sorption and desorption of hexazinone in different soils were evaluated. Samples from seven Brazilian soils were collected and separated into two subsamples, with and without limestone incubation. Hexazinone was quantified using ultra high-performance liquid chromatography. The sorption and desorption coefficients were determined in soils using Freundlich isotherms. Increasing the pH did not alter the sorption kinetics of hexazinone in the same soil class. The shortest sorption time of hexazinone occurred in soils with higher organic matter (OM) and clay content. Liming reduced the sorption and increased the desorption of hexazinone in the soils, which was caused by the increase in pH and reduction of OM content. Although the application of limestone increased desorption, the rate at which this process occurred was less than the sorption rate of hexazinone in most cases. In alkaline soils, the recommended dose of hexazinone for pre-emergence application should be low to avoid leaching and reduce the contamination of groundwater resources.