The study showed that soil treated with organic fertilizers retains more carbon!

As the level of carbon dioxide in the atmosphere has increased in recent decades, there is a growing need to find strategies for carbon capture and retention.

Researchers from the University of Kansas (K) are studying how different farming methods can affect the amount of carbon stored in the soil. Using a Canadian light source (CLS) at the University of Saskatchewan (USA) and an advanced light source in Berkeley, California, they analyzed the soil of a corn field in Kansas, which has been cultivated without tillage for the last 22 years.

During this time, the farm used various methods of nitrogen management in the soil, including the absence of fertilizers, chemical fertilizers and manure/compost. The results were published in the journal of the American Society of Soil Science.

"We tried to understand what mechanisms underlie the increase in carbon reserves in the soil using certain management methods," says Dr. Ganga Hettiarakchi, professor of soil and environmental chemistry at the University of Kansas. "We considered not only soil carbon, but also other soil minerals that will help store carbon."

As shown in other studies, researchers from K-state found that soil treated with manure or compost fertilizer stores more carbon than soil that received either chemical fertilizers or did not receive any fertilizers. But even more interesting, according to Hettiarakchi, is that the ultra-bright synchrotron light allowed them to see how carbon is preserved: they found that it persists in the pores, and some part of the carbon attaches to minerals in the soil.

The team also found that soil treated with manure or compost contains more microbial carbon, which indicates that these improvements support more microorganisms and their activity in the soil. In addition, they identified special minerals in the soil, says Hettiarakchi, that processing contributes to active chemical and biological processes.

"As far as I know, this is the first direct evidence of the mechanisms by which organic improvements improve soil health, microbial diversity and carbon sequestration."

Since synchrotron visualization is non-destructive, K-state researchers were able to observe what happens in soil aggregates (lumps) without the need to destroy the soil; in fact, they studied the chemistry of carbon in its natural state.

"Collectively, such research will help us move to more sustainable, more regenerative farming methods that will protect our soils and environment, as well as help feed the growing population," says Hettiarakci. "In addition, understanding the role of different minerals, chemicals and microbes involved will help improve models for predicting how different agricultural methods affect soil carbon storage."