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Research article2005Peer reviewed

Stochastic modeling of diffuse pesticide losses from a small agricultural catchment

Lindahl AML, Kreuger J, Stenstrom J, Gardenas AI, Alavi G, Roulier S, Jarvis NJ

Abstract

The objective of this study was to identify the main sources of variation in pesticide losses at field and catchment scales using the dual permeability model MACRO. Stochastic simulations of the leaching of the herbicide MCPA (4-chloro-2-methylphenoxyacetic acid) were compared with seven years of measured concentrations in a stream draining a small agricultural catchment and one year of measured concentrations at the outlet of a field located within the catchment. MACRO was parameterized from measured probability distributions accounting for spatial variability of soil properties and local pedotransfer functions derived from information gathered in field- and catchment-scale soil surveys. At the field scale, a single deterministic simulation using the means of the input distributions was also performed. The deterministic run failed to reproduce the summer outflows when most leaching occurred, and greatly underestimated pesticide leaching. In contrast, the stochastic simulations successfully predicted the hydrologic response of the field and catchment and there was a good resemblance between the simulations and measured MCPA concentrations at the field outlet. At the catchment scale, the stochastic approach underestimated the concentrations of MCPA in the stream, probably mostly due to point sources, but perhaps also because the distributions used for the input variables did not accurately reflect conditions in the catchment. Sensitivity analyses showed that the most important factors affecting MACRO modeled diffuse MCPA losses from this catchment were soil properties controlling macropore flow, precipitation following application, and organic carbon content

Published in

Journal of Environmental Quality
2005, Volume: 34, number: 4, pages: 1174-1185
Publisher: AMER SOC AGRONOMY

      SLU Authors

    • Kreuger, Jenny

      • Department of Soil Sciences, Swedish University of Agricultural Sciences

        • Gärdenäs, Annemieke

          • Department of Soil Sciences, Swedish University of Agricultural Sciences

          • Jarvis, Nicholas

            • Department of Soil Sciences, Swedish University of Agricultural Sciences

          UKÄ Subject classification

          Agricultural Science

          Publication identifier

          DOI: https://doi.org/10.2134/jeq2004.0044

          Permanent link to this page (URI)

          https://res.slu.se/id/publ/4481