Using large-scale facilities to study novel fertilisers

​The manufacture of mineral fertilisers such as ammonium nitrate or urea produces almost 2% of global greenhouse gas emissions. Organo-mineral fertilisers use much less of these mineral ingredients, combining them with organic material such as manure or straw.

However, the organic materials are naturally varied, unlike the standard mineral ingredients. For farmers, reliability between batches is important, and the industry needs a way of assessing variability and ensuring the new fertiliser will be suitable for widespread application.

In this study, Professor Ruben Sakrabani used STFC’s national laboratories to study pellets of a novel fertiliser produced by combining organic material, a small amount of mineral ingredients, and carbon dioxide from carbon capture. His paper, published in Frontiers in Sustainable Food Systems, is the first to use large facilities to evaluate the physical and chemical properties of these fertiliser pellets.

Ruben used neutron imaging on the IMAT beamline at ISIS, X-ray computed tomography at Diamond Light Source and Raman spectroscopy at the Central Laser Facility. “Neutrons turned out to be a great technique for investigating the pellets as they are non-destructive, which means we could assess the variability in the pellets while keeping them intact,” explains Ruben.

His neutron experiment was so successful that he returned for further beamtime at ISIS. As the sample is very dark, there were some issues with fluorescence during the Raman spectroscopy, but the X-ray measurements were very complementary to the neutron experiment.

Ruben first heard about the facilities at the Rutherford Appleton Laboratory through the STFC Food Network+. They initially seemed very far away from his area of research, but he attended one of their sandpits and “one thing led to another.”

“The STFC Food Network was instrumental to me discovering these techniques,” he says. “The use of STFC facilities is uncommon in food and agriculture scientists. The network encouraged me to think outside the box. It was exciting to come to RAL and see the amazing facilities. The support from the scientists was just wonderful.”

The experiments showed the internal structure of the pellets, proving that the manufacturing process produces intact pellets that could be applied successfully using a spreader. These spreaders propel the pellets up to 36 m across a field, and it’s important that the pellet remains intact during this process, giving an even distribution of fertiliser and therefore crop growth.