Farmers’ statements are reliable – Comparing two different data sources about glyphosate use in Germany

Abstract Data on agricultural pesticide use are of increasing interest since understanding farmers’ pesticide use patterns is crucial for farm business, farm advisory, and agricultural and environmental policy. Member states of the European Union established different systems to estimate applied amounts of active ingredients per crop and hectare. However, the aggregation of use data at crop level lacks information of farm-specific use patterns. Former studies showed that pesticide use varies strongly between farms. Consequently, approaches are needed to obtain more farm or field-specific data of pesticide use. Glyphosate is the most applied active ingredient worldwide and widely used in Germany. Studies have been carried out in recent years to analyze glyphosate use patterns in German arable farming. For this study, data of a glyphosate-related survey conducted among German farmers were compared with field record data from on-farm studies. Using data originating from the two different sources will help to judge the comparability and adequacy of the methods. This comparison has not been done before for the case of glyphosate or any other pesticide. Questionnaire-based surveys among farmers correspond predominantly with field records, even in the highly political case of glyphosate. In view of glyphosate use patterns, the study indicates that many farmers are not fully aware of the difference between two uses currently registered: stubble and pre-sowing applications. In the on-going public debate, consistent definitions of glyphosate uses are needed to ensure clear communication between stakeholders.