As Goes Iowa, So Goes the World
In addition to the necessary cessation of fossil fuel combustion, in order to actually stop flooding and reverse global warming, almost all the industrial grain production fields in the world will need to return to the short, medium and tall-grass prairies they once were - restoring prodigious soil carbon stocks and their water holding capacities.
Iowa used to be nearly 100% tall-grass prairie, with literally the best, most carbon-rich soils on earth, referred to commonly as “black gold.” Today it is almost entirely in industrial soy and corn with nearly 7 inches of this precious topsoil lost since 1850.
Enabling this conversion back to native soil requires holistically managed grazing. Recent studies show that properly managed grazing can restore between 1 to 3 tons of carbon per acre per year. Iowa has approximately 30 million acres in farmland. If this were restored to prairie, we could be sequestering 30 to 90 million tons of carbon per year in Iowa alone. In addition to the climate mitigation that provides, the flooding mitigation is enormous. The NRDC (2015) calculates that each 1% increase in SOM per acre to 6 inches holds an additional 20,000 gallons of water. This would provide the state an additional water holding capacity of 600 *billion* gallons of water or the equivalent of over a day's outflow from the Mississippi River at its mouth in New Orleans.
The rate to achieve this of course depends on many factors, but must, in any case, be pursued extensively and in earnest. A back-of-the-envelope rate calculation is as follows: Using estimates from the NRDC (2015), a 1% increase in SOM equates to approximately 4.5 tons of carbon (per acre to 6 inches). Machmuller (2015) demonstrated an increase of approximately 3 tons C per acre per year to 30 centimeters (approx. 12 inches), and showed that such increases can continue for 2 to 7 years. Thus, using Machmuller and assuming an even distribution of SOM across the 30 cm top profile (approximately 1.5 tC/yr in the top 6 inches and 1.5 tC/yr in the bottom 6 inches), a 1% increase in SOM to 6 inches (4.5 tC) may be achieved in as little as 3 years. Again, this rate calculation is just a thought experiment, but it is plausible given known data. The important point is that such increases are within our reach and we must work toward them.
Teague, W. R., Apfelbaum, S., Lal, R., Kreuter, U. P., Rowntree, J., Davies, C. A., . . . Byck, P. (2016). The role of ruminants in reducing agriculture's carbon footprint in North America. Journal of Soil and Water Conservation, 71(2), 156-164. doi:10.2489/jswc.71.2.156 http://www.jswconline.org/content/71/2/156.abstract
Stanley, P. L., Rowntree, J. E., Beede, D. K., DeLonge, M. S., & Hamm, M. W. (2018). Impacts of soil carbon sequestration on life cycle greenhouse gas emissions in Midwestern USA beef finishing systems. Agricultural Systems, 162, 249-258. doi: https://doi.org/10.1016/j.agsy.2018.02.003
Machmuller, M. B., Kramer, M. G., Cyle, T. K., Hill, N., Hancock, D., & Thompson, A. (2015). Emerging land use practices rapidly increase soil organic matter. Nature Communications, 6, 6995. doi:10.1038/ncomms7995
NRDC (2015) Climate-Ready Soil: How Cover Crops Can make Farms More Resilient to Extreme Weather Risks
IOWA’S “BLACK GOLD” IS WASHING AWAY
Iowa Farm & Land Statistics
New study: Up to 7 billion tonnes of Carbon Dioxide can be removed from the atmosphere each year through better soil management on farm land
Holistic Planned Grazing
Flooding in Davenport