Organic farms are better at sequestering carbon than soil from conventional farms, shows research conducted by scientists Geoffrey Davies and Elham Ghabbour, at Northeastern University. Over the past ten years, Davies and Ghabbour have been elbow-deep in analyzing soils from different parts of their country. According to Ghabbour, a soil expert, organic soil can hold more carbon because it has higher concentrations of humic acids. These acids are the reason behind the brown pigmentation of the soil we see in our backyard, as opposed to the sandy-blonde or ashy-red varieties. Humic acids bind to the soil making it more fertile, allowing it to retain water, and assisting plants in absorbing nutrients. Therefore, the presence of this compound (humic acid) allows more carbon to be captured and stored for a long term in organic soil, becoming a contributing factor of global warming and greenhouse gases.
In collaboration with the Organic Center, a nonprofit research and education organization, and working with citizen scientists from different parts of the world, Ghabbour and Davies collected and analyzed 659 organic soil samples from 39 states and 728 conventional soil samples from all 48 contiguous states. The result was that organic soil samples have 44 percent higher levels of humic acids than conventional soil samples. These findings were published in Advances in Agronomy. The research was an evidential study that gave away the implications for the climate and overall health of the planet due to organic soil. They described the method of their experiment in the paper with the hope that other labs around the world will replicate their findings.
Ghabbour has been studying humic acid since 1982. She joined Northeastern in 1993 when she and Davies built the Humic Acid Research Group. “She’s the leading expert on the subject,” Davies said. One of the important and early discoveries of this group was finding humic acid molecules in a live plant. Up to that point, scientists had thought it came only from decomposing plants. Humic acid is still shrouded in mystery, even today. “We hope to be able to find a chemical structure from the spectrum of humic acids,” Ghabbour said. “We’ve only suggested model structures at this point.
Researchers also don’t know why organic soil has higher concentrations of humic acid than conventional soil. However, they have a theory.
“One of the reasons could be that feeding soils with fertilizers kills this material,” Davies said. Humic acids act as natural fertilizers, selectively binding to toxins and releasing nutrients in the soil. The synthetic alternative to humic acids is man-made “plant food” like Miracle-Gro and other fertilizers. But while these products can be effective, “It’s not building soil. It’s giving plants quick food” Ghabbour said. “The humic acids in soil are healthier for the soil long term.”
Dibyasha Das