Avoiding Subsoil Compaction under No-Till

With the passage of time, crop yield losses can occur on no-till farmland. Researchers from Agroscope and the Universities of Graz and Nevada demonstrated how subsoil compaction can lead to yield losses.

In addition to permanent soil cover and a balanced crop rotation, no-till is one of the most important approaches for conservation farming. Practised worldwide on around 15% of arable land, this minimally invasive form of arable farming offers ecological and economic benefits such as lower energy consumption and less soil erosion.

Yield losses and subsoil compaction

Despite these benefits, global meta-studies show that no-till can lead to persistent yield losses, especially with maize crops, and this even decades after transition to no-till. Researchers from Agroscope and the Universities of Graz and Nevada discovered a possible reason for this: subsoil compaction, which is primarily caused by the use of heavy farm machinery in moist soil conditions.

But why, exactly, does this happen? According to the study, compaction builds up when the frequency of compaction events is higher than the natural regeneration rate of the soil. In this situation, soil compaction leads to reduced rootability, worse water and nutrient access, and long-term soil-function losses.

Relevance worldwide and for Switzerland

The researchers estimate that approximately 40% of no-till land worldwide, i.e. around 0.8 million km², is exposed to an increased risk of soil compaction. No-till is practised on a large scale in North America, South America and Australia. To date, the percentage of farmland under no-till in Europe has been low, with only around 5% of arable land being managed without systematic mechanical cultivation. Soil compaction, however, is a major problem in all management systems. Switzerland also makes use of powerful, heavy machinery. Furthermore, moist soils in temperate regions such as Switzerland are by nature more prone to compaction. Consequently, the results of the study may be of general interest for agricultural practitioners, since soil compaction can also occur under most forms of soil management in Switzerland.

Agroscope conducts research for a sustainable agricultural sector in Switzerland

Together with national and international partners, Agroscope has developed the online tool ‘Terranimo’ for practitioners to prevent such soil compaction whenever possible. Agroscope is currently conducting two long-term field trials studying both the regenerative capacity of the soil and various measures for loosening the subsoil. Agroscope researchers from different disciplines are also involved in a joint European project investigating the importance and functions of the subsoil for agriculture.