It’s a process that is as old as humankind taming fire and growing crops. The practice of returning carbon to the soil through charcoal (called “biochar” when put into the ground) from fires has been known for centuries to have a positive effect on plant growth.
Now, thanks to some work done at the Canadian Light Source in Saskatoon, advocates of using biochar know the reason why charcoal works so well in capturing and releasing nutrients such as nitrogen and phosphorus slowly into the soil to improve crop yields over an entire growing season and beyond. The findings could lead to the creation of an organic slow release fertilizer with significantly better performance than current agricultural management practices.
The answer researchers from Europe got in a trip to the CLS beamlines was not the one that everyone had previously presumed. Instead of the old assumption that oxidization of biochar enabled the storage and release of nutrients for crops, team leader Nikolas Hagemann says the CLS allowed researchers to see the actual pathway. Martin Obst, one of Hagemann’s collaborators and frequent user of the CLS, used the soft X-ray spectromicroscopy beamline to get a picture at the molecular level so they could see how other nutrients such as composted manure clung to the biochar due to size and shape of the carbon molecules. Incorporated into soil, the biochar is slow to give up the nutrients clinging to it.