Where should we stash carbon? Look down

Paul Hawken on stage at GreenBiz 16
Flash Gordon Murray
Paul Hawken on stage at GreenBiz 16 in Scottsdale, Arizona.

All the while we’ve been strategizing to reduce the carbon flowing into the air, the ground beneath our feet is in dire need of it.

Soil just may be the perfect carbon sink, Professor Peter Byck of Arizona State University told attendees of the GreenBiz 16 event, underway in Phoenix this week. Agricultural soil in most of the developed world has been depleted of half its carbon, which plants need to grow.

"We are looking at closing the carbon cycle," said Byck, describing the carbon sequestration and grazing pastureland project he has undertaken with students, farmers and scientists. Byck has produced the films "Carbon Nation" and "Soil Carbon Cowboys."

He is working with cattle ranchers in North Dakota, Mississippi and Saskatchewan in Canada who have take up natural grazing or what a team of scientists studying its climate-change impacts call Adaptive Multi-Paddock Grazing.

"In soil, the biggest bang for the buck is adaptive multi paddock grazing (AMP) — emulating how bison migrated across the great plains," Byck said. "Those plains had the most amazing soil, with carbon 10 feet deep."

Instead of growing just one crop on pastureland and dousing the soil with fertilizers, pesticides and herbicides to keep it producing for cattle, these ranchers move their cattle to new fields, or field sections called paddocks, and allow the previous field to regenerate or repopulate with naturally growing plants, sans fertilizers and pesticides. 

The previous field regenerates with diverse wild flowers, legumes and grasses. With help from microbes, pollinators and photosynthesis, these plants and grasses grow robustly, and take up carbon from the air. Carbon can remain within the root system and the soil if certain conditions prevail.

"Are these ranchers sequestering carbon in the soil? Just that one question has led me down an amazing road," Byck said. "We’ve built this team here at [Arizona State]" with scientists, farmers and other ag universities. "What we want to do is see if we can sequester 1 million tons of CO2 annually on farms in the U.S."

Moreover, they want to multiply the effort. After three years it wants to up its 1 million ton pilot goal to try to sequester or put back in the soil 10 million tons of carbon. Then six years out it hopes to expand that even more to as much as 100 million tons of carbon taken back into pastureland soil.

Byck is pursuing whether ranching in this regenerative way can make up for — or cancel out — the methane that cattle produce. The answer is not yet clear.

But it leads to yet another, larger question, Byck said. Could regenerative pasture store carbon emitted from fossil-fuel-burning power plants and vehicles? "Can you take oil, burn it and so emit carbon, but take that carbon and put it back in the soil?"

Shell Oil is funding Carbon Nation's project with two Shell GameChanger grants to find out, supporting the studies underway between Byck’s team at ASU and cattle ranchers.

Shell has been supporting carbon capture and sequester experiments. The grant seeks to find a feasible business model for supporting ranchers' transition to regenerative AMP grazing rather than paying to store carbon. 

AMP mimics herd migration by breaking up a ranch into small pastures called paddocks and ushering cattle to a new paddock each day while the previous areas regenerate. Pastures are left to recover for 80 days and the results so far, Byck said, is they grow resplendent with a diversity of plants, richer soil and healthier cattle.

The jury is still out, however, on whether widespread practice of this ranching style can cancel out methane emissions from cattle ranching. Livestock produce nearly 15 percent of greenhouse gas emissions, and cattle that produce beef and milk make up 65 percent of that, according to the United Nations Food and Agriculture Organization.

Carbon as a good thing

Paul Hawken, founder of Project Drawdown and author of The Ecology of Commerce, phrased the issue this way: "Carbon is in the wrong place" — emitted by the millions of tons into the atmosphere and changing climate patterns.  

He is all for "bringing carbon back home" to where nature housed it in the first place  in soil, in animals, plants and humans, as the building block of living things. "Carbon is good. It's just that it is not where it belongs. We want it in our soils, our bodies."

Hawken sees great promise in methods that draw carbon out the air and put it to use in production or farming or energy generation. Project Drawdown is identifying processes and activities that reduce carbon or convert atmospheric carbon to useful things. The organization, which will release a book in 2017, includes 17 land-use solutions among its findings so far.

In the decades since people began to work on stemming climate change, "nobody has made a list of the 50, 70 or 100 most substantive solutions," Hawken said. "We are doing that and seeing what would happen if they were scaled."