Microbes Carry a Lot of Carbon to Their Graves

Tuesday, September 5, 2017

My newsletters are consistently about improving soil fertility, and carbon sequestration is a key part of that process. What’s interesting is that carbon sequestration is still poorly understood despite years of research. I believe that where technology is making its greatest impact on agriculture is in accurately measuring things that we’ve only guessed at in the past, and some new work on carbon sequestration is a case in point.

Recently three scientists, in an effort to understand how organic matter contributes to long-term carbon storage, have come up with new thinking focused on microbial biomass. Julie Jastrow, one of the scientists, who works for the DOE’s Argonne National Laboratory, affirms that “soil is important to life on Earth as we know it. Soil organic matter is key to many of the essential services and functions that soils provide.”

It has long been held that the remnants of decayed plant matter were the principal components of stabilized soil carbon. Plant litter, mostly dead leaves, stems and roots, decomposes and transforms into soil organic matter. However, the researchers have shifted perspectives, concluding that dead microbial biomass and other microbial residues could contribute even more significantly to stable carbon pools. This finding would be a game changer, one that every grower should look to take advantage of in their effort to better stabilize and renew vulnerable or degraded soils.

“When researchers compared the amount of living microbial biomass with the annual inputs from plants, it just seemed natural to think that the bulk of soil organic matter had to come from plant litter,” Jastrow noted. However, even though the living biomass of microbes is small, these organisms grow, live and die at a rapid pace. As a result, their contribution to soil organic matter can be much greater than previously thought.

Through anabolic activity, microbes synthesize complex molecules from simpler ones, including carbon dioxide, which contributes to carbon storage. When the microbes that have fed on the plant materials die, their residues are more likely to become “entombed” in the soil than plant residues independently, and thus they have a greater impact on carbon sequestration and overall soil health.

These new insights give us pause in how we look at our work and our offerings to growers. We have the capability to supply growers with millions of diverse microbes through the application of compost teas, like MetaGrow ST, which we have been advocating for years. MetaGrow ST is a simple and effective means to introduce large and diverse populations of microbes. In addition, plant matter largely volatilizes into CO2 without microbial populations to process it, and an opportunity to build additional organic matter is lost. So, dollar for dollar, we can provide a compelling solution to build stable carbon in the soil, leading to very productive farmland.

Our compost teas already provide growers with benefits throughout the growing season, like helping crops process micronutrients early in the season for a consistent bud break, helping crops maintain quality fruit during high stress times like heat waves, helping to push ripening and, at post-harvest, helping crops store much-needed reserves though the long dormancy period. Entombing plant residues via the introduction of massive microbial quantities will undoubtedly improve overall soil health, and it may have a larger impact on improving carbon sequestration than ever before realized.