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Compaction of subsoil is a hidden but persistent damage that impairs a range of soil functions and ecosystem services. We analyzed the soil compaction issue in the Driver-Pressure-State-Impact-Response (DPSIR) context. The driving force (DPSIR-D) is the farmers' efforts to sustain economic viability. This entails a steady increase in the size and weight of the agricultural machinery (DPSIR-P) exerting the specific pressures on the soil system. Simulations using historical data for agricultural machinery show significant increases in the mechanical stresses exerted on the soil profile during the last five decades. Surveys and comparative measurements (DPSIR-S) in the literature indicate that much of the European subsoil is compacted to critical levels for cropping. This calls for changes in agricultural management (DPSIR-R). Mechanical stresses impact the soil (DPSIR-I) by reducing the volume, dimensions, and interconnections of soil pores. Subsequent impacts on ecosystem services (subtle DPSIR-I aspects) include a decrease in crop production, an impaired soil filtering of pollutants, and the risk of higher greenhouse gas emissions. The natural ability of compacted subsoil to recover is poor. We highlight the need to expand the DPSIR concept to include a risk assessment methodology to identify sustainable management systems. Risk assessment involves the evaluation of the mechanistic cause-effect chain of the compaction process. Measured data as well as modeling indicate that contemporary tires are not able to carry the loads frequently inflicted on wet soil without exerting critical stresses on deep subsoil layers. We suggest the use of online modeling tools that combine existing knowledge. Such tools may also create maps of vulnerable areas from the field to the continent scale. Groups of stakeholders including researchers, farmers and their consultants, and policy-makers need to identify sustainable traffic systems that secure both presently focused ecosystem services as well as nonuse soil values (the bequest for future generations). [ABSTRACT FROM AUTHOR]

Several investigations have shown that the distribution of vertical stress in soil just below a loaded tyre is not uniform. The stress distribution and the size and form of the tyre–soil interface are decisive for the stress propagation in the soil profile. We measured the distribution of vertical stress in the contact area for two radial-ply agricultural trailer tyres (650/65R30.5 and 800/50R34) loaded with ∼60kN. The study took place on a sandy soil at a water content slightly less than field capacity. We tested the effect of three different inflation pressures (50, 100 and 240kPa) in a randomised block design with three replicates. The vertical stress was measured with load cells located in 0.1m soil depth. The vertical stress data were used also for identifying the soil area in contact with the tyre, i.e. the tyre footprint. A model (named FRIDA) is proposed that describes the tyre footprint by a super ellipse and the stress distribution by a combined exponential (perpendicular to the driving direction) and power-law (along the driving direction) function. The contact area doubled when the inflation pressure was reduced from 240 to 50kPa. For both tyres, the measured peak stress increased significantly with tyre inflation pressure and was generally about 90kPa higher than tyre inflation pressure. The model-fitted maximum stress was about 50kPa higher than the inflation pressure. The 650/65R30.5 tyre displayed a longer footprint and a more uniform stress distribution in the driving direction and performed better at non-recommended inflation pressures than the 800/50R34. At the recommended inflation pressure, both tyres displayed a stress distribution across the width of the wheel that could be evaluated as optimal with regard to a minimised topsoil compaction. The suggested model seems very well suited for describing real stress distributions at the soil–tyre interface, but should be validated also with other tyres, wheel loads, and soil conditions. It has the potential to improve soil compaction models considerably and also for use to evaluate important features of tyres with scope to improve future designs. [Copyright &y& Elsevier]