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Isoproturon Sorption and Degradation in a Soil from Grassed Buffer Strip
Author(s) -
Benoit P.,
Barriuso E.,
Vidon Ph.,
Réal B.
Publication year - 1999
Publication title -
journal of environmental quality
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.888
H-Index - 171
eISSN - 1537-2537
pISSN - 0047-2425
DOI - 10.2134/jeq1999.00472425002800010014x
Subject(s) - sorption , soil water , chemistry , mineralization (soil science) , soil horizon , organic matter , environmental chemistry , environmental science , soil science , agronomy , adsorption , biology , organic chemistry
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 ( K d = 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 ( K d = 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 K d and K oc 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.