Residue and Dissipation Kinetics of Metsulfuron-Methyl Herbicide in Soil: A Field Assessment at an Oil Palm Plantation

Zainol Maznah,Oii Kok Eng,B Sahid Ismail

doi:10.3390/biom10071067

Zainol Maznah, Oii Kok Eng + Show 1 more

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https://doi.org/10.3390/biom10071067

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Abstract

A field trial experiment was conducted to investigate the degradation of metsulfuron-methyl at two application dosages, 15 g a.i/ha and 30 g a.i/ha, at an oil palm plantation. Soil samples were collected at ‒1, 0, 1, 3, 7, 14, and 21 days after treatment (DAT) at the following depths: 0–10, 10–20, 20–30, 30–40, and 40–50 cm. The results showed rapid degradation of metsulfuron-methyl in the soil, with calculated half-life (t½) values ranging from 6.3 and 7.9 days. The rates of degradation of metsulfuron-methyl followed first-order reaction kinetics (R2 = 0.91–0.92). At the spray dosage of 15 g a.i/ha, metsulfuron-methyl residue was detected at up to 20–30 cm soil depth, at 3.56% to 1.78% at 3 and 7 DAT, respectively. Doubling the dosage to 30 g a.i/ha increased the metsulfuron-methyl residue in up to 30–40 cm soil depth at 3, 7, and 14 DAT, with concentrations ranging from 1.90% to 1.74%. These findings suggest that metsulfuron-methyl has a low impact on the accumulation of the residues in the soil at application dosages of 15 g a.i/ha and 30 g a.i/ha, due to rapid degradation, and the half-life was found to be 6.3 to 7.9 days.

Highlights

Metsulfuron-methyl is a low-use-rate sulfonylurea herbicide widely used for post-emergence broadleaf weed control in oil palm plantations
The results show that metsulfuron-methyl residue degraded to a level that was undetectable by 21 Days after treatment (DAT)
Ismail and Azlizan [26] reported that the half-life of metsulfuron-methyl depends on the soil type, soil temperature, and moisture content

Summary

Introduction

Metsulfuron-methyl is a low-use-rate sulfonylurea herbicide widely used for post-emergence broadleaf weed control in oil palm plantations. Degradation of sulfonylurea herbicides in soil is directly related to pH-dependent hydrolysis of the sulfonylurea bridge [4]. Once metsulfuron-methyl reaches the soil, it can be mineralized by microbial activity [5,6,7]. The major routes of metsulfuron-methyl mineralization in the environment are via the cleavage of the sulfonylurea bridge, O-demethylation of the methoxy–triazine moiety, and triazine ring opening after O-demethylation [8,9]. It has been reported that both metsulfuron-methyl hydrolysis and biological transformations were highly dependent on the soil temperature and moisture [9,10,11]. Soil pH plays a significant factor in affecting both sorption behaviour and chemical degradation of metsulfuron-methyl in the soil, due to its ability to influence the ionization state of the herbicide [9,12,13,14]

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