Methods

Field and greenhouse trials

Field trials are the central tool of agronomic and agroecological research. On selected plots (on-farm or on-station) we quantify soil quality, input and output of water and nutrients, environmental factors, yield, and product quality in the course of entire cropping cycles. Established and innovative management strategies (irrigation, fertilisation, tillage, crop rotations) are compared systematically, whereby each project takes its site-specific context into consideration.

Labelling with stable isotopes (¹⁵N) is used to track matter flows through various pools and compartments, in order to elucidate basic mechanisms of interaction.

Experiments at smaller scales, in the greenhouse or climatic chambers, can complement critical aspects of the field trials, and are used to establish new methods.

Nutrient analysis

The analysis of nutrient cycles in agro-ecosystems requires the determination of C, N, P, K, S, minerals and pollutants (heavy metals) in all components of the system, i.e. in soil-, plant-, manure- and water-samples. Besides the horizontal (input/output) flows we routinely collect data on vertical nutrient flows (losses by leaching and gaseous emmissions) by ion exchange resins and trace gas measurements by photoacoustic techniques.

Land use patterns

High resolution aerial photographs (2 - 5 cm resolution), remote sensing, and GIS allow analysing agro-ecosystems beyond the field scale in a larger spatial context. This analysis aims at identifying and quantifying source and sink regions, nutrient cycles and potential gaps. Eventually this allows to derive options for environment-friendly and resource-efficient management.