The Root Rangers have been given a unique view of their soil structure and root systems through X-ray Computed Tomography (CT) scanning.
Dr Craig Sturrock of the University of Nottingham explains that CT scans were used to compare soil ‘cores’ from the different farms. The farmers took samples from their chosen fields of first winter wheat using sections of plastic pipe (15 cm x 8 cm). These were hammered into the ground before being carefully excavated to preserve the structure of the soil and roots inside. Each of the Root Rangers took 10 samples in a typical w-formation, five samples from the treated area under scrutiny in their trials and five from the untreated area. These samples were then posted to the University’s laboratory for scanning.
Craig explains: “It’s been a really exciting first year of the project, using the imaging technology to visualise the structure of soils across the UK, completely non- destructively, which is usually really difficult to see.
“We’ve found some nice differences between the soils. There’s variations between geographical location, soil texture, treatments, and differences in the root structure.”
CT scanning is a non-invasive technique to look at the structure and interior of the sample. It discriminates different materials based on density so more dense areas of materials appear brighter in the images. Soil pores, which are low density, appear darker. A high-powered computer then turns those 2D images into a 3D visual to show us what’s going on under the ground.
Analysis of the CT scan images measured the average porosity of the soil cores at typically 6% across all samples. It also measured mean pore thickness, orosity and connectivity of the pore network.
The scans highlighted the importance of biopores – channels created by roots and soil organisms – in soil health. These structures were evident across different soil types and management practices, providing pathways for root growth and water movement.
There was also evidence of healthy soil ecosystems, with numerous signs of biological activity. “There’s certainly lots of evidence of earthworms,” adds Craig. “There’s lots of biology there, keeping the soils nice and healthy.”
Different soil textures exhibited distinct characteristics in the scans. For instance, clay soils showed a blocky structure, while sandy soils displayed a lot of coarser grains.
The research highlighted the impact of management practices, such as ploughing and grazing.
The results were not always as expected, with ploughed soil showing minimal differences to min or no-till. This may have been related to the time of sample collection being relatively late in the growth season (May 2024), where the soil has had time to settle after cultivation the previous autumn.
In year two the Root Rangers are repeating the sampling process, but this time with five soil cores just from untreated areas. Sampling is taking place in March so tillage differences between sites may be more apparent.
“I’m really looking forward to seeing how the results will look and what more we can learn from repeating the sampling,” notes Craig.