Soil compaction by increasing wheel loads major threat for soil health 

Soil compaction has been described as one of modern agricultures major problems. Increasing intensification of agriculture and with that, the increasing use of heavy machinery is one of the main contributors to soil compaction.  Soil compaction potentially causes a decrease in soil qualities like permeability of water and air, infiltration capacity, water storage, oxygen supply and rootability. This can lead to decreases in crop productivity, economic losses, drought, surface water pollution, and natural disasters. According to the European Commission (2020) the best estimates suggest that between 23 to 33% of European land fails soil health due to soil compaction, of which 7% is outside of agricultural areas. Based on several international studies it was concluded that this soil compaction can result in production losses for farmers between 10 to 40%. Two types of soil compaction can be distinguished: topsoil (down to 25 cm below the surface) and subsoil compaction (between at least 25-50 cm below the surface) In agricultural soils, the arrangement of the pore system often differs between topsoil and subsoil the topsoil can better be described as a sponge-like pore system with random structure due to tillage, while the subsoil is more structured and mainly has vertical (bio)pores that determine air transport. Plants need different resources from both topsoil and subsoil and therefore compaction in any of these layers can result in limited access to resources. However, topsoil compaction can quickly recover with the right management practices, while subsoil compaction is difficult to recover and can even be permanent.

In the presentation the following will be addressed:

• What is topsoil and subsoil compaction? (and why focus on subsoil)
• Major cause of compaction by increasing wheel loads (and why innovations increases the problem)
• The influence on subsoil compaction on soil functions,  water bearing capacity and runoff (and how this influence the use of fertilizers)
• Resolving the wicked problem of soil compaction (and why it’s also a social-economic problem)