X-rays show new soil detail
High-tech Australian devices have revealed the ‘hidden half’ of grain.
Researchers have used a new synchrotron-based imaging technique that captures the complex interaction of soil and roots in 3D.
“For a long time, we have described this area as the ‘hidden half’, because we really have little information about what is going down there where the soil, air, roots, and organic matter form a heterogenous clump or to assess the things that we do to improve them,” says soil science expert Dr Peter Kopittk.
Because of the enormous soil constraints in Australia due to salinity, acidification and sedimentation, there are multi-billion dollars losses to the agricultural industry every year.
The new technique, which has been developed to complement existing agricultural field studies, opens the possibility of predicting the impact of key nutrients and fertilisers that are administered by farmers to improve soil quality.
“The roots are as important as the above-ground shoots, so this is a significant leap forward in understanding if interventions will improve crop yield,” said Dr Kopittke.
The technique involves creating 3D-imagery from X-ray tomographic images, showing in detail the fine network of roots enmeshed in a large soil sample.
In a preliminary analysis, the team collected tomographic images of a wheat plant that had been fertilised with phosphorus at a depth of about 15 centimetres. Plants access nutrients from the entire soil depth, not just the surface.
Previously farmers had no way to determine beforehand if the costly application of phosphorus at depth, which requires special equipment, would produce an improved yield.
“The information is hidden below the surface. For a farmer who makes this investment and sees no improvement, this is a bad situation to end up in,” explains Dr Kopittke.
“You can see quite clearly that there is a proliferation of roots at the depth where the phosphorus fertiliser was applied.”
Another advantage of the technique is the ability of the synchrotron X-ray beamline to accommodate large samples.
Samples for laboratory-based X-ray studies are usually about the size of a soft drink can and this does not capture the extensive root system that is spread out beneath the ground.
“These large samples are much more representative of what is actually happening in the real world environment of the field,” said Dr Kopittke.