Influence of cropping system factors on pesticide use intensity – A multivariate analysis of on-farm data in North East Germany

Abstract

We analysed pesticide use data of 539 winter wheat fields grown on seven commercial farms in North East Germany in the seasons 2001–2007. The data were originally collected as part of economic analysis. The aim of our study was to show the impact of agronomic measures typical for integrated pest management (IPM) on pesticide use intensity.We used multivariate methods including hierarchical clustering and unconstrained ordination to describe variability of pesticide use and to identify pesticide use patterns. 166 fields had a complete record of eight crop management variables characterising rotation, tillage, cultivar, seeding time and N fertilisation. We subjected pesticide data of these fields to an ordination constrained by crop management data and considered weather and farm characteristics as co-variables influencing the pesticide use intensity.Crop management had a measurable effect even beyond the single farm and changing weather conditions: it accounted for approx. 10% of the explained variability of pesticide use. Pesticide intensity is adjusted by farmers to overall cropping intensity. Fields which were managed with typical IPM characteristics like late seeding and resistant cultivars were treated with a lower pesticide intensity. The downside of our findings is that these lower input CM systems are typically used only on less productive sites.Variability of pesticide use was mainly influenced by the farm, this factor accounted for 37% of explainable variance. We discuss two components of this high explanatory power: (I) farm characteristics which determine overall cropping intensity and (II) the routine of treatment decisions on the farm.We discuss the implications of our results regarding robust study design and sampling for pesticide use monitoring. To enhance IPM adoption in the context of recent European pesticide regulations, we identify the need for: (I) studies on the economy of reducing pesticide use by integrating agronomic measures, and (II) identification of innovative farmers for possible farmer to farmer exchange on successful IPM adoption.