Modelling soil compaction risk under climate change: an analysis of wheel load carrying capacity for different pedoclimatic zones in Europe

Climate change affects the agriculture in manifold ways. One important point is the change of the weather conditions, which results in variation of precipitation and temperature. Both, precipitation and temperature changes, will affect plant and root growth as well as the available water content in the soil. In addition to many other soil and plant processes, soil moisture has a major influence on soil strength. A change in soil moisture due to climate change will therefore have an impact on the trafficability of soils and the risk of soil compaction. However, it is currently not known to what extent and in what direction the trafficability and soil compaction risk may change as a result of climate change.

In this study, we used a modelling approach to analyse the behaviour of soil compaction risk in times of climate change. First, we collected soil, crop and weather data from 12 different pedo-climatic zones in Europe. Using a new version of the SaSCiA model (Spatially explicit Soil Compaction risk Assessment), we calculated the wheel load carrying capacity (WLCC) for the last two decades. To model the effects of climate change, we selected 10 different climatic models and 2 SSP-scenarios (SSP1-2.6 and SSP5-8.5). For each pedo-climatic zone, we calculated the WLCC for each climate model and each SSP-scenario from present to 2100 on a daily basis.

The results show that climate change will increase the WLCC and thus potentially reduce the soil compaction risk. In the short-term (2020-2050), a slight increase of maximum 5.1% of WLCC occurred on average across all study sites when comparing SSP5-8.5 (worst-case scenario) with SSP1-2.6 (best-case scenario). In the long-term (2051-2100), the WLCC increased by 17.8%. The largest increases in WLCC occurred from May to the end of October. From January to April, only minor changes were recorded. At this time, soils are often at field capacity which is likely to be reached in the future. The soil compactions risk therefore remains high during this period, which has an impact on slurry spreading, for instance.

In addition to the average long-term effects, the variation in the WLCC between years is significantly high. There is an irregular alternation of dry and wet years within certain periods. The effects of these dry or wet years exceed the long-term changes in WLCC caused by climate change. This is an important point, as the compaction of the subsoil lasts for a long time.