BayCEER Workshop 2026

Seasonal dynamics and soil management operation effects on soil hydraulic properties

Soil hydraulic properties, such as the water retention curve (WRC) and the hydraulic conductivity curve (HCC), are often treated as static. However, WRC and HCC depend on soil structure, which can be altered, particularly in the macro-pore range, by processes such as soil management operations and bioturbation throughout a season. Experimental data on the magnitude of these changes, the potential range of soil structures affected, and their seasonal dynamics remain limited.

In this study, we collected undisturbed soil cores at six time points across two growth seasons (after seeding, during the growing season, and post-harvest) from the topsoil (5–10 cm depth) in a 30-year field trial conducted by the Bayerische Landesanstalt für Landwirtschaft. We sampled plots managed by conventional ploughing and direct seeding. To quantify soil hydraulic properties from saturation to oven dryness, four laboratory methods were applied to the same soil core: the Falling Head method, the Multistep Flux method, the evaporation method and the dewpoint method.

Seasonal dynamics were observed, particularly in the conventional plough treatment, where bulk density shows a clear pattern of loss after tillage, followed by compaction again after harvest, by around 8%. For both treatments, seasonal changes in WRC were observed from saturation to pF 3, with the greatest changes occurring after harvest and seeding. For the HCC, we observed highly bimodal behaviour and seasonal dynamics near saturation (0-1.5 pF), indicating the effect of tillage voids and biopores on near-saturation conductivity. The plant available water for direct seeding was 1-2% lower than for the conventional plough treatment in the growing-season measurements.

We conclude that agricultural management operations and seasonal dynamics in soil structure control the wet range of HCC and the WRC from saturation up to pF 3. Overall, this study presents experimental evidence of the effect of soil structure on SHP and its potential effect on soil water dynamics.