Environmental Project No. 1178 2007 – Evaluation of Pesticide Scenarios for the Registration Procedure

Evaluation of Pesticide Scenarios for the Registration Procedure

1. Introduction

The Danish Environmental Protection Agency is currently using mathematical modelling results to support their pesticide approval procedure. Up to now the modelling results derives from the EU scenario Hamburg (sand) as well as the two Danish model scenarios Karup (sand) and Langvad (clay), see Appendix A, B and E for further details. The data supporting the three scenarios is very limited. Hamburg is thus not supported by any calibration, and Karup and Langvad have been calibrated against a large scale yearly water balance only.

However, the improved data availability obtained in recent years has made it possibly to assess the reliability and representativeness of the scenarios hitherto being used in the Danish registration procedure. Studies providing field data including/excluding model setup describing pesticides leaching in Denmark comprise:

Field studies on plot scale of movement of herbicides and soil particles to field drainage tiles have been conducted at Højbakkegård, west of Copenhagen (Petersen et al., 2002).
Large scale modelling project developing a numerical model for prediction of pesticides in surface water in the catchments of Lillebæk and Odder (Miljøstyrelsen, 2004).
The Danish Pesticide Leaching Assessment Programme (PLAP), an intensive monitoring programme aimed at evaluating the leaching risk of pesticides under field conditions (Lindhardt et al., 2001; Kjær et al., 2004). Detailed pedological and hydro geological characterisation and an intensive long term monitoring enabled transport and leaching of applied pesticides and conservative tracers at five field sites.

Among the three studies, this project’s steering committee decided to make use of the PLAP data, which provide the most extensive data sets and well-parameterized and -calibrated model scenarios of flow and bromide transport.

The objective of this study was thus to:

Present an overview of all eight scenarios with regard to the physical soil properties and the climatic conditions.
Give a historical and site specific description of the present model scenarios (Langvad, Karup, and Hamburg) and the PLAP scenarios (Jyndevad, Tylstrup, Silstrup, Estrup, and Faardrup) including a short description of the numerical models behind the scenarios.
Compare the simulated pesticide leaching ability of the present model scenarios’ with that of the PLAP-scenarios.
Assess the impact of application date on the simulated pesticide leaching of the PLAP scenarios.
Evaluate the reliability and representativeness of the present model scenarios and the PLAP scenarios with the purpose of recommending the two scenarios to be used in the coming registration procedure.