Ploughing in regenerative agriculture

Disclaimer: This article has been machine translated from Danish to English, so please note that there may be errors in the translation.

Regenerative agriculture aims to improve soil health and fertility. With over 60% of Europe's soils in poor condition, many see regenerative agriculture as a solution to issues such as declining crop security and the climate footprint of agriculture. In particular, a focus on carbon sequestration plays a key role. Although the potential for carbon sequestration is debated, the consensus is that degraded soils have room for improvement.

The plough has often been portrayed as the main cause of declining soil health. The logic is that ploughing damages soil structure, microbiology and carbon content compared to reduced or no tillage. However, the problem is not the plough, but how you use it.

Plough with care

The role of the plough in regenerative agriculture is complex. It's all about using it wisely.

• Set the plough correctly

• Don't use the plough more than necessary

• Vary the ploughing depth and don't plough wet soil

• Consider how big your plough and tractor need to be

• Plant growth is essential for microbial life

Carbon sequestration and tillage

Previous research has suggested that no-till farming could increase soil carbon, but many studies have only measured carbon in the top 15-25 cm of soil, giving a skewed picture.

Recent research shows that no-till practices primarily redistribute the carbon content, concentrating it closer to the surface, without necessarily increasing the total amount of carbon in the soil. The higher carbon content in the topsoil provides benefits such as better water infiltration and fertilisation. The downside is that the conversion of carbon occurs faster close to the soil surface than in the deeper soil layers, so the gains can be lost more quickly.

Soil structure is affected by ploughing

Ploughing significantly changes the physical properties of soil. It breaks up aggregates, which can weaken bearing capacity and increase the risk of erosion and leaching. Therefore, it is important to establish plant cover quickly after ploughing to minimise these risks. Ploughing can also create a plough sole - a compact layer under the plough layer that inhibits root growth and drainage. By varying the ploughing depth and avoiding ploughing wet soil, damage can be limited.

The role of microlife

Soil microlife is at the centre of regenerative agriculture. Microorganisms such as bacteria, fungi and protozoa support soil nutrient cycling and plant growth. Ploughing especially affects fungi negatively as their long hyphae are easily damaged. However, microorganisms regenerate quickly under the right conditions. Air, water, heat and food are the most important factors for microbial activity, and increased plant growth - not the absence of ploughing - is essential to support this life.

Ploughing temporarily increases soil CO2 emissions as microorganisms are activated by better oxygen and temperature conditions. But this activity is also necessary to decompose organic matter and release nutrients to plants, and the increased emissions do not directly lead to a decrease in soil carbon compared to no-till systems, according to research, so the carbon loss via CO2 appears to be offset by other factors overall.

Can the plough be used regeneratively?

Ploughing can promote deeper root growth and improve growing conditions for crops, especially where weeds or poor soil structure inhibit production. No-till farming can be said to do the same when drought limits yields. This is of course a gross oversimplification, but reflects the broad outlines of the latest soil research.

Used correctly, the plough can reduce the need for chemical or mechanical weed control and help establish a better seedbed. The plough can also expand the range of species that can be used in cover crop mixtures by lowering the risk of creating a weed problem. This provides opportunities to have growing plants for a greater part of the year, which in turn contributes to soil regeneration.

Reduced tillage is the long-term goal

A higher soil carbon pool can reduce the need for ploughing over time because carbon-rich soils have better structure and are easier to work with. Therefore, reduced tillage should be seen as a long-term goal rather than a means in itself. Right now, ploughing may be necessary in many places to achieve the most important thing in regenerative agriculture: strong and healthy plants with deep roots.

Read more

Memo: Tillage and carbon build-up (pdf 17 pages) (in Danish)