Root sampling of main crops across Europe

In July, EJP SOIL researchers defied the heatwave to sample roots in winter wheat and maize - and thereby quantify root biomass of 10 different varieties across Europe. The purpose was to assess if an optimized variety selection for more root biomass could increase soil carbon.

Photo: Coring in maize sites (Pic 8 - see text)

To reduce the effect of climate change on food security, carbon farming is indispensable.

Mobilizing crop producers to support this transformation requires promotion of cropping systems with equivalent profitability, but higher soil carbon sequestration. The most viable yet neglected option is through increased and deeper roots of main and cover crops.

The EJP SOIL project MaxRoot-C is working to close this knowledge gap by providing hard data on the root carbon inputs of main crop varieties and different cover crops across the EU.

On July 17th the sampling campaign of roots in winter wheat and maize officially started, as two teams of researchers went out to collect more than 4500 roots samples at 15 sites in 10 countries (Pic. 1).

Root sampling of winter wheat in the Hungarian summer heat

The two teams, led by the EJP Soil partners Juliane Hirte from Agroscope, Switzerland and Felix Seidel from the Thünen Insitute, Germany, met at a site in Southeast Hungary in order to begin the winter wheat sampling together -  at 38°C.

- The main aim was to quantify root biomass of 10 different varieties across Europe to assess if an optimized variety selection for more root biomass at similar and stable yield could increase soil carbon, says Anna Wawra, who is a research scientist at the Austrian Agency for Health and Food Safety and communication representative in the project.

For this, two methods were chosen, where cutting frames from the top soil (25x25x15cm) were used to accurately determine crown roots (Pic. 2) and top soil root biomass as well as steel augers for subsoil root biomass down to 1 m depth (Pic. 3 and 4 respectively).

- After the teams harmonized their sampling approach in Hungary, they took separate paths and Agroscope headed to the southern sites while the Thünen Institute went north. The winter wheat sampling (Pic. 5) took about 6 weeks for each team and lasted until the beginning of September, says Felix Seidel.

Clear differences in root biomass

After a brief break the maize sampling followed swiftly with a slightly different approach: Four sites across France have been sampled where a paired plot design with irrigated and rainfed plots was set up (Pic. 6). Here, samples were taken with the shovelomics approach (Pic. 7) for top soil root biomass determination as well as with steel augers for subsoil root biomass (Pic. 8).

- All in all, the campaign was a great success. In the field, we could already see clear differences in root biomass between varieties, sites and irrigation treatments in the case of maize (Pic. 9 and 10 respectively) and many roots that went even down to 1 m depth, says Juliane Hirte.

Now, all samples are being washed, scanned, dried and finally weighed and analysed in the lab. We expect first results in spring 2023 which will subsequently be presented at the next annual science days of EJP Soil. Further, additional in-depth studies for selected sites and varieties were conducted e.g. to determine mycorrhization.

Further information

You can visit the MaxRoot-C website here

You can visit the combinex MaxRoot-C and MixRoot-C website here

Follow the updates and see more pictures of the campaign on the MaxRoot-C twitter account

If you have any further questions about the project, please contact Anna Wawra,

Texts for photos: