HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Figures Only Full Text Free Full Text (PDF) Free Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Web of Science (4) Citing Articles via Google Scholar Google Scholar Articles by Lecomte, V. Articles by Le Bissonnais, Y. Search for Related Content PubMed PubMed Citation Articles by Lecomte, V. Articles by Le Bissonnais, Y. GeoRef GeoRef Citation Agricola Articles by Lecomte, V. Articles by Le Bissonnais, Y. Related Collections Water Quality Agricultural Pesticides Structure and Properties Soil Models Water Pollution

TECHNICAL REPORT
Surface Water Quality

Soil Surface Structure Effect on Isoproturon and Diflufenican Loss in Runoff

^a INRA, Avenue de la Pomme de Pin, BP 20619 Ardon, 45166 Olivet Cedex, France
^b INRA/INA-PG, BP 01, 78850 Thiverval-Grignon, France
^c BRGM, 3 Avenue Claude Guillemin, 45060 Orléans Cedex, France

* Corresponding author (Lecomte-Morel{at}exchange.brgm.fr)

Received for publication October 16, 2000. Because soil surface structure has a considerable influence on infiltration rate, the sealing process is postulated to have a significant effect on herbicide loss through runoff. We evaluated the effect of degraded soil surface structures on herbicide loss in runoff, and used the experimental data to test the uniform mixing zone concept and two-site sorption kinetics for modeling herbicide transfer to runoff. The experiments were done with simulated rainfall on 10-m² plots in the field and 0.25-m² plots in the laboratory after a surface application of 1.5 kg ha^-1 of isoproturon [3-(4-isopropylphenyl)-1,1-dimethylurea] and 0.187 kg ha^-1 of diflufenican [2',4'-difluoro-2-(,,-trifluoro-m-tolyloxy) nicotinanilide]. Isoproturon (IPU) and diflufenican (DFF) concentrations were very high in the first runoff (up to 60 mg L^-1 for IPU and 2 mg L^-1 for DFF) when simulated rainfall was applied 24 h after the treatment. The concentrations decreased very rapidly with total rainfall depth. Degradation of the structural state of the soil surface increased the ratio of pesticide loss to application rate from 0.3 to 10% for IPU and from 0.7 to 7.8% for DFF for a runoff depth of less than 1 mm. The structural state of the soil surface influences the rapidity at which runoff begins after the onset of rain, and the runoff coefficient at steady state. Furthermore, the development of a surface seal seems to limit the depth of soil–runoff interaction and thus influences the dynamics of herbicide mobilization. Concentrations of IPU in the runoff were satisfactorily described with a model incorporating a uniform mixing zone and two-site sorption–desorption.

Abbreviations: CI, couche d'interaction (uniform mixing zone) • DFF, diflufenican • IPU, isoproturon