Aarhus University Seal / Aarhus Universitets segl

Soil compaction should receive attention on World Soil Day

Soil compaction below the plough layer is an increasing problem due to heavy farm machinery. For the past five years, Aarhus University has focused on this threat in an EU project about soil quality. This work has provided important knowledge about compaction mechanisms and the possibilities of mitigating the problem.

[Translate to English:] Jordpakning kan ødelægge jordens frugtbarhed. Foto: Per Schjønning


Every year on December 5, the UN celebrates World Soil Day to highlight the role of the soil resource in the food supply and protection of the environment. Via their participation in the EU project RECARE, researchers at Aarhus University have focused on subsoil compaction damages due to the steadily increasing weight of agricultural machinery. 

- From many previous studies we know that compaction of the soil below the plough layer is very long lasting if not permanent. In normal years, the sustained negative effect on yield from subsoil damage appears to be around five percent. Unfortunately, a short-term financial analysis may imply that it is most profitable here and now to continue using very heavy – but efficient – machinery. In such a situation, it is important that we as a society increase our knowledge about farming profitability as well as effects on the environment. We also need to address the possibilities of changing the current practice, says Senior Researcher Per Schjønning from the Department of Agroecology at Aarhus University. 

RECARE ran from November 2013 to November 2018 and included more than 20 European countries from Iceland in the north to Cyprus in the south. 

In Denmark, Aarhus University, in collaboration with the company AgroIntelli, investigated the soil compaction threat. Several studies in existing field trials gave valuable knowledge about the effect of heavy traffic on the subsoil. At two workshops in 2015 and 2016 possible solutions were discussed with farmers, advisers, the agricultural machine industry, NGOs, and farmers’ organisations as well as representatives from Ministry of Environment and Food of Denmark. Later on, the researchers sent questionnaires to approximately 5000 farmers. 

The work in RECARE has pointed out that the damages to the soil originate not only from the weight of the machines. Beneath the driving wheels of the tractor, shear deformation of the soil seems to add significantly to the impact on soil functions. 

– It is important to investigate this extra dimension of soil compaction. In a new project, COMMIT, we are quantifying the effects of the pulling power and the effects of repeated wheeling, says Senior Researcher Lars J. Munkholm, who is project leader of the continuing investigations. 

RECARE also resulted in a recommendation to politicians and decision makers about what can be done to abate the damaging effects of soil compaction. The researchers point out that market forces will not necessarily change the situation regarding the very heavy machines. RECARE also recommended that a broader mention of agricultural soil protection be included in the EU's common framework for soil protection. 


You can also read the following articles:

Soil under pressure (about RECARE)

Machine design and crop choice can reduce soil compaction (about COMMIT)

You can read the latest news from RECARE here.


For more information please contact:

Regarding RECARE: Senior Researcher Per Schjønning, Department of Agroecology, telephone: +45 8715 7725, e-mail: per.schjonning@agro.au.dk

Regarding COMMIT: Senior Researcher Lars J. Munkholm, Department of Agroecology, telephone: +45 8715 7727, email: lars.munkholm@agro.au.dk