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Food

Managed Grazing

Mob grazing on Brown’s Ranch in North Dakota.

Grazing animals create extraordinary environments—witness the Serengeti plains and tall grass prairies of the United States. Where original grasslands are still intact, they are abundant lands with carbon-rich soils. They benefit from the activity of migratory herds that cluster tightly for protection; munch grasses to the crown; disturb the soil with their hooves, intermixing their urine and feces; and then move on.

Managed grazing imitates these herbivores, addressing two key variables: how long livestock grazes a specific area and how long the land rests before animals return. There are three managed-grazing techniques that improve soil health, carbon sequestration, water retention, and forage productivity:

  1. Improved continuous grazing adjusts standard grazing practices and decreases the number of animals per acre.
  2. Rotational grazing moves livestock to fresh paddocks or pastures, allowing those already grazed to recover.
  3. Adaptive multi-paddock grazing shifts animals through smaller paddocks in quick succession, after which the land is given time to recover.

Improved grazing can be very good for the land and sequester from one-half to three tons of carbon per acre. However, it does not address the methane emissions generated by ruminants (cattle, sheep, goats, etc.), which ferment cellulose in their digestive systems and break it down with methane-emitting microbes.

References

André Voisin…theory of…managed grazing: Voisin, André. “Grazing Management in Northern France.” Grass and Forage Science 12, no. 3 (1957): 150-154; Voisin, André. Grass Productivity: An Introduction to Rational Grazing. Washington, D.C.: Island Press, 1988.

meta-analysis of…impacts of grazing: McSherry, Megan E., and Mark E. Ritchie. “Effects of Grazing on Grassland Soil Carbon: A Global Review.” Global Change Biology 19, no. 5 (2013): 1347-57.

carbon [sequestered] per acre: Tennigkeit, Timm, and Andreas Wilkes. “An Assessment of the Potential for Carbon Finance in Rangelands.” Working Paper No. 68. Nairobi, World Agroforestry Centre, 2008; Conant, Richard T. Challenges and Opportunities for Carbon Sequestration in Grassland Systems: A Technical Report on Grassland Management and Climate Change Mitigation. Rome: Food and Agriculture Organization of the United Nations, 2010.

pastures…70 percent of…agricultural land: Toensmeier, Eric. The Carbon Farming Solution. White River Junction, VT: Chelsea Green Publishing, 2016.

increasing [soil] carbon: Toensmeier, Solution; Flannery, Tim F. Now or Never: Why We Must Act Now to End Climate Change and Create a Sustainable Future. New York: Atlantic Monthly Press, 2009.

Will Harris…“heritage and responsibility”: McKenna, Maryn. “From Factory Farm to Organic Icon: Inside White Oak Pastures.” Modern Farmer. September 2013.

holistic and humane system: Byck, Peter. One Hundred Thousand Beating Hearts. 2016. http://www.carbonnationmovie.com/about/clips/244-one-hundred-thousand-beating-hearts-short-film

“how can I make this land better?”: Reece, Chuck. “The Dirt Underneath.” The Bitter Southerner. May 5, 2015.

organic matter…ten times higher: Reece, “Dirt.”

Gabe Brown…“going to help live”: Montgomery, David. Growing a Revolution. New York: W.W. Norton & Company, 2017.

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Errata

p. 74

Correction: Improved grazing typically sequesters a few hundred pounds of carbon per acre, but in some cases as much as three tons per acre.

Correction: Many who started at 1 percent organic matter are now at 6 to 8 percent, or more.

Correction: Brown has taken soil organic matter from 4 percent to 10 percent in six years.

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