Modelling the relationships and feedbacks between spatial patterns of anecic earthworm populations, related preferential flow pathways and agrochemical transport and degradation in rural catchments

• Applicant: Professor Dr. Boris Schröder-Esselbach
• Subject Area: Ecology of Land Use
• Term: from 2007 to 2011
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 46178417

Earthworms play a pivotal role in agro-ecosystem functioning by modulating soil structure that significantly influences soil hydraulic properties, organic matter dynamics, and plant growth. This project focuses on anecic earthworms like Lumbricus terrestris which create vertical semi-permanent burrows that function as preferential flow pathways. Preferential flow in macropores is a key process which strongly affects infiltration and may cause rapid transport of pesticides into depths of 80 to 150 cm where they experience a much slower degradation. Therefore, preferential transport is an environmental problem because the topsoil is bypassed, which has been originally thought to act as a filter to protect the subsoil and shallow groundwater. Assessing the environmental risk of pesticides in earthworm burrows and how human management practise feedbacks on that risk requires the development of an integrated eco-hydrological model. This model allows predictions of i) the spatiotemporal distribution and population dynamics of anecic earthworms, ii) the related pattern of connective preferential flow pathways (i.e., earthworm burrows), and iii) the space-time pattern of infiltration and travel depth distribution of solutes. This enables the understanding of how small-scale patterns regulate large-scale processes in rural landscapes and how feedbacks between earthworm engineering and transport characteristics affect the functioning of (agro-)ecosystems. We expect our final model to be applicable for catchment-scale risk assessment that may assist agrochemical registration.

• DFG Programme: Research Grants
• Participating Person: Professor Dr.-Ing. Erwin Zehe