A laboratory study of the mineralization and binding of 14C-labeled herbicide rimsulfuron in a rendzina soil

Abstract The fate of pyrimidine-2- 14 C-rimsulfuron in a rendzina soil was investigated using a laboratory microcosm approach. Measurement of CO 2 evolution suggested that rimsulfuron applied at 5 times the recommended dose did not affect soil respiration. Under abiotic conditions, no mineralization of 14 C-rimsulfuron into 14 C-CO 2 occured and under biotic ones it was very low reaching 0.75 % of the applied 14 C-rimsulfuron after 246 days of incubation. The analysis of data showed that a three-half order model provided the best fit for the mineralization curve. Extractable 14 C-residues decreased over time to 70 – 80% of the applied 14 C-rimsulfuron at the end of the incubation. After 246 days of incubation, non extractable residues (NER) accounted for up to 24.7 % of the applied 14 C-rimsulfuron and were distributed according to organic carbon in soil size fractions, suggesting a progressive incorporation process of NER to soil humus.