Isoproturon Sorption and Degradation in a Soil from Grassed Buffer Strip

Abstract

The fate of the herbicide isoproturon [3‐(4‐isopropylphenyl)‐l,1‐dimethylurea] was investigated in soil from a grassed buffer strip. Compared to a cropped soil originating from the same experimental site (Kd = 1.8 L kg−1), sorption of isoproturon was enhanced in the grassed soil and especially in the surface layer (0‐2 cm) containing high proportion of nondecomposed plant residues (Kd = 5.0 L kg−1). Nonhumified organic fractions isolated from the surface soil layer and corresponding to above and bdow‐ground plant residues derived from the grass exhibited high sorption coefficients Kd and Koc compared to the rest of the soil. Reversibility of sorption was lower in the grassed soil than in the cropped soil and decreased rapidly with time. A rapid degradation of isoproturon was observed at different depths of the grassed soil whereas most of the herbicide remained nondegraded in the cultivated soil: half‐lives were respectively 72 d in the cultivated soil, and only 8 d in the superficial layer (0–2 cm) of the grassed soil. The highest mineralization rate of the isoproturon ring (20% after 35 d) was observed in the top layer (0–2 cm) having the highest mineralization rates of organic matter. In relation with this fast degradation, a large proportion of isoproturon residues became nonavailable to water and methanol extractions (54% of the initial applied isoproturon found as nonextractable (bound) residues). Thus the grassed strip surface soil had a high potential to dissipate isoproturon trapped from run‐off.

Degradation of imazosulfuron in different soils—HPLC determination

“…The screening method using HPLC coupled with UV detection has been extensively used to monitor the degradation of pesticides in soils (Anderson and Dulka, 1985;Shneiders et al, 1993;Thapar et al, 1995;Benoit et al, 1999) EXPERIMENTAL PROCEDURE Chemicals and soils. Imazosulfuron (Fig.…”

TRANSPORT AND FATE OF ATRAZINE IN MIDWESTERN RIPARIAN BUFFER STRIPS1

“…Benoit et al (1999) reported high levels of sorption and rapid degradation of isoproturon in soil from a perrenial ryegrass (Lolium perenne) buffer strip. Mersie et al (1999a) used small boxes of soil and simulated runoff to assess the effect of switchgrass buffers, which increased herbicide retention over bare soil.…”

Shallow water table effects on water, sediment, and pesticide transport in vegetative filter strips – Part 2: model coupling, application, factor importance, and uncertainty

“…For pesticide inputs, field measurements of the percentage of clay (PTC) and organic carbon (PCTOC) of the upper field followed a uniform PDF (Lacas, 2005;Benoit et al, 1998;Madrigal-Monarrez, 2004). The triangular distribution for KOC for the pesticides evaluated at each site is based on measurements in Jaillière for the base value and boundaries (Benoit et al, 1998;Souiller et al, 2002) and on Morcille for the base value (Lacas, 2005) but using boundaries from the PPDB database (IUPAC, 2007).…”

“…The triangular distribution for KOC for the pesticides evaluated at each site is based on measurements in Jaillière for the base value and boundaries (Benoit et al, 1998;Souiller et al, 2002) and on Morcille for the base value (Lacas, 2005) but using boundaries from the PPDB database (IUPAC, 2007).…”