Covering the land with living plants works

Keeping the soil continuously covered with living plants stimulates soil life and carbon storage. Both are essential in developing a good soil structure, which in turn ensures good water infiltration and storage. This soil cover can be achieved in different ways: catch crops such as rapeseed or phacelia can offer solace in wintertime, grass can be sown under in corn fields and grass strips planted between rows of fruit trees. All agricultural practices come with their own advantages and disadvantages. These plants will take up water as well, which can be a problem in regions that struggle with year-round drought.

Reduced or no-tillage farming is not the holy grail answer

Experiments focusing on reduced or no-tillage farming have been conducted for many years. Still, the results of those experiments have been mixed. Where water availability seems to improve, soil compaction increases. Effects of reduced tillage on water infiltration and runoff are ambiguous. In addition, tillage reduction also increases the presence of weeds, which in reality usually results in increased usage of herbicides by those farmers that decide to leave the plow for what it is from time to time. However, reducing soil compaction does have clear positive effects. Rather than installing tillage bans, we might want to evolve more to less, well-timed and lighter machining on the land in general – and to a restoration of compacted soils in the process.

Adding, returning or keeping organic material on the field ensures a better soil structure

According to a small number of studies, organic carbon is like the mortar in the house of soil. It holds soil particles together and improves soil structure. The research on what farmers can ideally add to their soils to improve structure is often interwoven with questions about other practices, like tillage reduction. Singling out the effects of adding organic material from the effects of tillage is difficult in such studies. Still, the benefits of organic additions such as plant residues, compost, manure, wood chips and biochar cannot be denied. The local availability of this material, preferably in large quantities, remains the big challenge here.

Scientists are fascinated by one material specifically: biochar. It is the charcoal that is created from burning plant material at high temperatures without oxygen. This charcoal is very stable and can exist for years in the soil, which is not the case for other plant materials. Despite scientists’ great excitement for this stable good, farmers are not sharing in the enthusiasm so far. Use of biochar remains limited, showing once again that practical implementation of farming practices takes more than delivering scientific evidence. Practices need to fit into the daily operating of the farm, and the economical and legislative framework and scientific knowledge need to reach the farmer.

Different strokes for different folks soils, farms and farmers

Even though some practices clearly showed up as beneficial, the main takeaway remains that farming is very context-specific. No single practice is ideal in all combinations of soil, climate and crops and no single practice can be seen unattached to the entire context of the agro-ecosystem it exists in. No matter how much organic material you add to the soil, there won’t be much effect if you proceed to destroy your soil structure by driving over it with heavy machinery while it’s wet. Thus, we need to stay away from generalizations and keep investigating how those context-specific relations between farming practices and water-regulating soil functions can be understood.

Policy is key

The CLIMASOMA project partners created two policy briefs to convince policymakers of the importance of their findings and guide them in the implementation:

• The first policy brief lists and clarifies the main conclusions of the project and calls on European policy makers to focus on green cover crops, organic additives, and rewarding less tillage in general rather than less ploughing in particular. But the importance of context and the specificity of countries, regions, soils, and farmers is also pointed out. Click here to download pdf document.
• The second brief takes a closer look at exactly how policymakers can approach this specificity and the implementation of these measures. The importance of context is given additional scrutiny here and policymakers are given advice on how to make the connection with farmers and in doing so increase the likelihood of implementation. Click here to download pdf document.

Articles about results from CLIMASOMA:

• Blanchy, G., Albrecht, L., Koestel, J., and Garré, S.: Potential of natural language processing for metadata extraction from environmental scientific publications, SOIL, 9, 155–168.
  • doi.org/10.5194/soil-9-155-2023, 2023

• Blanchy, G., Bragato, G., Di Bene, C., Jarvis, N., Larsbo, M., Meurer, K., Garre, S. 2023. Soil and crop management practices and the water regulation functions of soils: a qualitative synthesis of meta-analyses relevant to European agriculture. SOIL, 9, 1–20, 2023
  • doi.org/10.5194/soil-9-1-2023
  • https://soil.copernicus.org/articles/9/1/2023/soil-9-1-2023.pdf
  • https://www.sciencedirect.com/science/article/abs/pii/S09596526220499

• Jarvis, N; Larsbo, M; Lewan, E; & Garré, S. Improved descriptions of soil hydrology in crop models: The elephant in the room?, Agricultural Systems, Volume 202, 2022, 103477, ISSN 0308-521X,
  • https://doi.org/10.1016/j.agsy.2022.103477.

• Le sol comme solution aux extrême climatique