On April 12, the Department of Energy’s Advanced Research Projects Agency – Energy (ARPA-E) announced a new funding opportunity aimed at increasing the carbon storage potential of U.S. agricultural soils.  Land-use, which includes agriculture, is responsible for 25 percent of total greenhouse gas (GHG) emissions.  While reducing fossil energy use is key to limiting warming to the internationally agreed less than 2 degrees Celsius, it will be impossible to meet climate targets if emissions associated with land-use are not also addressed. At the same time, modern agricultural practices have severely depleted the natural reserve of soil carbon; however addressing soil carbon can reduce emissions associated with agriculture and store additional carbon in the soil.  This article explores both low- and high-tech approaches to “carbon farming” and the political and social appetite to use agriculture as a means to address climate change.

The ARPA-E initiative -- Rhizosphere Observations Optimizing Terrestrial Sequestration (or ROOTS), will use modern breeding and genomic tools to create crops that can help accelerate soil carbon storage. The agency expects to invest a total of $30 million in 8 to 12 projects that “modify, through targeted breeding and plant selection, crop plants to produce more roots, deeper in the soil profile,” which will in turn accelerate soil’s carbon storing abilities.  Through the ROOTS initiative, ARPA-E sets an ambitious target of a 50 percent increase in the carbon storage of soils, a 50 percent decrease in nitrogen emissions from conventional agriculture, and a 25 percent increase in water productivity. The net result would be a 10 percent reduction of total greenhouse gas emissions in the United States while also boosting the climate resilience of the agriculture sector.  

ROOTS will fund projects that will advance data collection, modelling of the root-soil interaction and creation of new plant characteristics that could enable greater soil carbon storage.  ARPA-E estimates that 87 percent of current U.S. cropland could benefit from these as-of-yet developed carbon storing traits and could accelerate the carbon storage potential of U.S. soils.    

ARPA-E is taking a high-tech approach to a long-understood problem – balancing soil carbon and agricultural productivity.  Modern agricultural practices, which have enabled ever higher agricultural yields and, therefore, lowered food prices and decreased food insecurity, have also reduced the soil’s carbon level. Carbon in soil is important because it helps store water, nutrients and regulate soil temperature. Increasing the amount of soil carbon can help address drought, water quality issues, nutrient management and climate resiliency – all thorny subjects in the agricultural world today.  Soil quality will also be key in addressing food security, as increasing soil carbon also translates to enhanced food production with potentially reduced inputs. 

Through more traditional farming methods, or “back to basics” if you will, farmers, the USDA’s Natural Resource Conservation Service (NRCS), grower’s groups and others have been exploring the potential of conservation and other measures such as cover crops, no-till and the use of biochar, which not only decrease the amount of fossil inputs on the farm but also increase the soil’s ability to store carbon.  Just one example can be found on Dave Brandt’s Ohio wheat, corn and soy farm, where he hasn’t tilled the soil since 1972.  Every winter, he plants over 10 varieties of cover crops, providing continuous living cover over the soil – a key ingredient in not only building soil carbon but preserving water holding capacity of the soil and maintaining water quality. Independent scientists have estimated that Brandt has increased the carbon content of his soils an astounding 61 percent in the past 35 years, with his corn yields increasing by up to 44 percent.  Brandt and other farmers are proving that it’s possible to pair conservation with productivity.

Despite these promising stories and developments, 24 percent of global agricultural lands shows decreased productivity, with another 1 to 2.9 million hectares of agricultural land becoming so degraded each year that it is unavailable to farm. In the United States, it is widely recognized that conservation measures are useful tools, but progress has been slow. Only 13 percent of U.S. farms are managed as no-till, with only 6 percent using cover crops. The barriers listed are numerous and complex; uneven policy support, lack of technical and financial assistance, as well as a conservative approach to farm management due to complex relationships between agricultural banks and farmers, as well as landowners and renters. Complicating matters is that farms, and soils, vary immensely, requiring more than a one-sized-fits-all solution to conservation.

Globally, the soil crisis is so severe that international policy makers have begun to again discuss the potential to rebuild soil carbon through climate policy. At the international climate change negotiations held last December in Paris, the French Agriculture Minister Stephane Le Foll called on the world to adapt “4/1000,” an initiative that would increase global soil carbon storage by 0.4 percent per year.  According to Le Foll, increasing soil carbon by just 0.4 percent a year would offset 4.3 billion tons of carbon dioxide emissions per year. While the initiative is voluntary at this point, it raises the possibility of carbon markets in agriculture.

If soil carbon is used as a mechanism to meet climate targets – measurement and verification becomes part of the conversation.  If implementing conservation measures that increase soil carbon is tricky, measuring, verifying and trading soil carbon credits has the potential to become a Pandora’s box. Through 4/1000, the French Ministry of Research is working towards enhancing the science and measurement of soil carbon, as well as engaging with farmers, scientists and policy makers on the issue.

Still, many in the agricultural community have significant concerns about a potential soil carbon trading mechanism -- who would fund this trading, who would benefit from trading, and who would control the credit system are all unanswered, and important questions.  


For more information see:

ARPA-E goes back to the ROOTS in $30M bid to transform carbon sequestration, Biofuels Digest

Recarbonizing Soils, National Institute of Environmental Health Sciences

What to make of the soil carbon initiative launched in Paris, Institute for Agriculture and trade Policy