Carbon, Cattle, & Conservation Grazing
September 15, 2019
By Brian DeVore, Land Stewardship Project
Editor’s note: George Boody will be discussing regenerative farming at Farm Table on October 26, 7 pm. The talk and conversation will include: rotational grazing, no-till, cover crops, and perennial crops and how these techniques improve soil health and sequester carbon–crucial in this time of climate change. The following is excerpted from a piece Brian DeVore originally published in October 2016.
Sometimes the rules of simple cause and effect don’t directly apply. Take, for instance, the fact that cattle are ruminants, and like all ruminants they utilize a wonderfully complex digestive system to turn forages and grain into meat and milk. A major side effect of all that fermentation on four legs is the production of methane, which is a potent greenhouse gas.
So, cattle are major villains in the global climate change battle, right? Not necessarily. In fact, according to a major research editorial in a recent issue of the Journal of Soil and Water Conservation, ruminants could hold one of the keys to developing a food production system that reverses the impacts of releasing so many greenhouse gases into the atmosphere.
This is just the latest recognition that agriculture has a huge potential role in bringing greenhouse gasses—carbon dioxide, methane, and nitrous oxide—under control. According to a paper published in the journal Nature in 2016, land use in general contributes about a quarter of total human-caused greenhouse gas emissions. Roughly 10 percent to 14 percent of emissions come directly from agricultural production and another 12 percent to 17 percent from land cover changes, including deforestation.
The good news is that soils have a huge potential for sequestering greenhouse gases. For example, our soil holds three times the amount of carbon dioxide currently in the atmosphere, and 240 times the amount of gases emitted by fossil fuels annually. Increasing the amount of carbon stored by our land by just a few percent would produce massive positive benefits. And since farmers deal directly with the land, they could play a significant role in developing what authors of the Nature paper call “climate-smart soils.”
The Journal of Soil and Water Conservation editorial was authored by researchers from the USDA, Iowa State University, Texas A & M, Ohio State University, and Michigan State University, among other institutions. They represent a broad spectrum of disciplines, from soil science and ecology to economics and animal husbandry. The team collected years of peer-reviewed research results and compared the relative contributions of greenhouse gas emissions from various agricultural practices, both conventional and conservation-based.
Their summary shows that it all comes down to how we treat the soil. When our land is plowed and becomes vulnerable to erosion, it is a net exporter of greenhouse gases. What goes on beneath the surface matters as well. As reported in Land Stewardship Project’s blog before, the incredible soil microbial diversity that once dominated the subsurface of native prairie areas has been almost completely eradicated by monocultural agriculture. Since tillage began, most agricultural soils have lost 30 percent to 75 percent of their soil organic carbon. That’s a big deal when it comes to climate change—the more carbon that stays in our soils, the fewer greenhouse gases in the atmosphere.
As a result, any farming practice that can keep soil from blowing or washing away, as well as keep it healthy enough biologically to sequester greenhouse gases, is going to have a major positive impact on our climate. That’s why authors of the Journal of Soil and Water Conservation editorial recommend a farming system that gets as much land as possible covered in continuous living cover 365-days-a-year.
Getting Livestock on the Land
Their solution? Get livestock out on the land.
The key phrase here is, “out on the land.” Producing beef and milk in intensive confinement, where feedstuffs are trucked in and liquid manure becomes a waste product that must be stored in massive quantities before eventually getting disposed of, is a major source of greenhouse gas emissions. In addition, such systems are reliant on monocultural production of corn, soybeans, and other crops. This results in a whole lot of greenhouse gas emissions as a result of tillage, as well as the petroleum based fertilizers, fuels, and pesticides involved in crop production.
But when livestock are raised on grasslands and other forages, the soil can be a sink for greenhouse gases, both because it is not being eroded and exposed to the elements, and because the world beneath the surface is building up soil organic carbon. It’s important to keep in mind that it matters how those animals are being grazed. Simply turning them out onto open pastures or rangelands and allowing them to roam at will creates its own problems. Overgrazing destroys plant communities and is a major source of erosion and compaction, not to mention water pollution.
Rather, rotating livestock through a series of paddocks, a system called managed rotational grazing, helps keep the grassland healthy above and below the surface by spreading nutrients sustainably and allowing plant life to rest and recover. The Journal of Soil and Water Conservation editorial cites several studies showing how this system—they call it “regenerative adaptive multipaddock conservation grazing” (there’s a mouthful)—can actually sequester more greenhouse gases than are being emitted.
Integrating Crops, Grass & Livestock
What’s particularly exciting about the Journal of Soil and Water Conservation editorial is the emphasis the authors place on integrating livestock, pastures, and crop production—a perfect mix of enterprises in the Midwest. They outline a working lands scenario where a carbon-trapping farm may have some permanent pasture that is broken up into rotational grazing paddocks. But it could also be producing corn and soybeans in a system where cover crops like cereal rye or tillage radish are used to blanket that row-cropped land with growing plants before and after the regular growing season. These cover crops could provide low-cost forage for cattle and other livestock, helping justify the cost of the cover crop establishment while protecting the soil from erosion and building its biology. Cover crops can also help cut a farm’s reliance on chemical fertilizers, which are another source of greenhouse gases.
The paper outlines the greenhouse gas emissions potential of several farming scenarios in North America, from keeping our current industrialized system—an increasing amount of grassland plowed under to make way for row crops; livestock confined in larger and larger Concentrated Animal Feeding Operations or CAFOs—to utilizing a combination of managed rotational grazing and conservation cropping systems that involve no-till, diverse rotations, and cover crops.
The differences are striking. Our current system of agriculture will continue to be a net producer of greenhouse gases, and things will only get worse as more of our world’s soil is damaged or lost. But even if 25 percent of our farming system is converted to managed rotational grazing/conservation cropping, agriculture will trap much larger amounts of greenhouse gases than it produces. Modifying what and how a bovine eats can more than make up for all that methane it belches up as part of the digestion process.
Under these scenarios, even reducing the number of ruminants that exist in North America by half doesn’t produce a system that sequesters greenhouse gases, as long as we keep our current soil-destroying industrialized cropping systems. We need animals out there contributing to a nutrient cycle that builds and protects soil while giving farmers an economic incentive to keep the land covered all year-round.
This wouldn’t necessarily require every farm to become a diversified crop/livestock operation. Some corn-soybean farmers are committed to raising crops and nothing else, both for economic and quality-of-life reasons. But under a more integrated system, diversity could be adopted on a more community-wide basis. Even crop farmers who do not have livestock could utilize their neighbor’s animals to add economic value to cover crops or that piece of pasture that hasn’t fallen under the plow yet. And the Marsden Farm study in Iowa has shown how diversifying a crop farm with longer rotations can help stabilize profits.
Both the Nature and Journal of Soil and Water Conservation papers recognize that there are major barriers to integrating livestock grazing/row-cropping in a soil-friendly manner, not the least of which is government policy that promotes the production of a handful of commodity crops and penalizes diversity.
“Rather than reducing ruminants and encouraging destructive agricultural land use by providing price subsidies and other subsidies, rewarding regenerative agricultural practices that focus on increasing soil [carbon] and that lead to greater adoption by land managers is essential to creating a robust, resilient, and regenerative global food production system,” conclude the authors of the Journal of Soil and Water Conservation editorial.
The idea that healthy soil could help us reverse the impacts of releasing so many greenhouse gases into the atmosphere is gaining a lot of ground. World leaders meeting in Paris during the 2015 U.N. Climate Change Conference hammered out a binding agreement that gives “carbon farming” a role in curbing greenhouse gases. The agreement, which was reached during parallel meetings held during the main conference, marks the first time using soil to capture carbon has become a formal part of the global response to climate change. Climate scientists and environmentalists are increasingly talking about how good soil health is a linchpin in not only fighting global climate change, but producing the kind of agricultural resiliency that can withstand the extreme weather events being produced by this phenomenon already.
Integrating livestock and conservation-based crop production can also make local rural communities more resilient, economically as well as environmentally. Farmers are proving that the managed rotational grazing/conservation cropping systems scenarios outlined in the Journal of Soil and Water Conservation editorial aren’t just the stuff of fancy computer models—real farmers are taking advantage of such synergies every day.
I’ve talked to several farmers recently who are, for example, utilizing the mob grazing of cover crops to provide cheap forage, build soil fertility, and reduce pressures on their grass-based pastures. The way they see it, continuous living cover is an excellent way of making better use of the solar energy above ground and biological activity below ground all year, not just when corn and soybeans are growing.
These farmers may not be calling it “climate smart” or “soil smart” agriculture. Just plain “smart” will do.