Dynamic of glyphosate mineralization in different soil types.

Abstract

Glyphosate [N-(phosphonomethyl)-glycine] is a largely used broad-spectrum, non selective, systemic, post-emergence herbicide. The object of this work was to study the dynamic of glyphosate mineralization in different agri-cultural soils characteristic to the western part of Romania: black chernozem, typical gleysol, phaeozom and slight vertisol with moderate carbonatation. The degradation experiment was conducted under controlled laboratory conditions using glyphosate-phosphonomethyl-14C-labeled with specific activity 2.2 mCi/mmol. The experimental re-sults indicated that the dynamic of glyphosate mineraliza-tion until the CO2 stage is different for each soil: the miner-alization of the herbicide is rapid in the first days of incu-bation and then decreases with time until the end of ex-perimentation. The mineralization curves for the soils had only two phases, the initial rapid phase, for about 20 days, followed by a slow final phase, when the curves attained plateaus. The initial rapid phase of degradation was attrib-uted to microbial action on the free glyphosate while the slower phase was due to the subsequent attack on the adsorbed glyphosate.