Effect of soil management on earthworm populations and soil hydraulic properties

MSc-Thesis of Dominik Schittli, conducted at the University of Zürich in colaboration with Agroscope.

Summary

Soil structure controls soil functional properties relevant to crop growth, such as hydraulic conductivity and water retention, which in turn affect water availability for crop systems. Soil management practices impact soil structure directly by loosening and compaction, and indirectly through management impacts on soil organic carbon content, earthworm abundance and activity, and root growth.

We assessed the impacts of soil management on soil structural quality, soil hydraulic properties, and earthworm abundance in a long-term field experiment (LTE) in Switzerland. The LTE had different treatment methods, including different levels of organic amendments, and tillage intensities. In-situ measurements and soil sampling were carried out in spring 2023, and later on during the year, the data was analysed. Results from the LTE show that treatment management had an influence on soil structural quality (VESS). Hydraulic conductivities near saturation also changed slightly under different management, but we could not detect significant statistical differences.

Further results suggest a positive correlation between soil hydraulic conductivity near saturation and earthworm number and indicate that earthworm abundance was more strongly affected by the tillage system than by organic amendments. In this master’s thesis, results from a Swiss LTE (FAST experiment) are shown, and we discuss the potential and limitations of agricultural soil management for climate change adaptation.