engleski

Persistence and mobility of green herbicides in agricultural soil

Integrated weed management practices and weed’s growing resistance against herbicides applied long-term introduced two new classes of herbicides onto the crop protection market in the 2000s. Triketone (mesotrione and tembotrione) and pyrazolone (topramezone) herbicides are considered efficient ecological substitutes for the recently restricted triazine herbicides, due to their chemical structure derived from a natural phytotoxin of certain plants belonging to the myrtle family. Since triketone and pyrazolone herbicides are more water soluble and mobile compounds than triazines, it is necessary to compare the behaviour of these three herbicide classes in agricultural soil under realistic environmental conditions. The present study investigated the persistence of mesotrione, tembotrione and topramezone in corn-cultivated soil after their post-emergence application at a registered and double-registered rate. The biodegradation rate and sorption intensity of herbicides in the same agricultural soil were evaluated under laboratory conditions. The calculation of herbicide leaching potential indices under the studied environmental conditions included kinetic and mobility parameters, as well as pedological and meteorological data. The conditions of microwave-assisted extraction and chromatographic determination were optimised for herbicide analyses in wet soil samples. The results showed faster field dissipation, slower biodegradation rate and higher soil mobility of topramezone compared to triketones. The biodegradation rate of herbicides in topsoil was slower at an enhanced application rate. Although the leaching potential index of topramezone in neutral silty loam soil with 1.2 % of organic carbon content was low, it was at least five times higher compared to the leachability class of triketones. Acknowledgement: this study was supported in part by the Croatian Science Foundation (No. 8366) and The Foundation of the Croatian Academy of Sciences and Arts (No. 10-102/284-2- 2015).

Herbicide ; Mesotrione ; Tembotrione ; Topramezone ; Persistence ; Mobility ; Soil ; Cornfield ; Weed control effectiveness

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