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What grass farmers have known all along—research shows grass sequesters carbon
By Martha Holdridge, West Wind Farm
Editor's note: This article is reproduced with permission from the Summer 2008 Grassfed Gazette, published by the American Grassfed Association.
|American Grassfed Association member Martha Holdridge, owner of West Wind Farm, used soil samples to determine that her West Virginia farm sequestered 15 tons of CO2 per acre over the past four years (photo by Kenny Kemp, Charleston WV Gazette).|
From 1987 to 2007, at West Wind Farm, we regularly sent soil samples from our pastures to the West Virginia University (WVU) testing lab--in some years requesting organic matter tests. In those same years, there has been increasing public alarm about greenhouse gasses and global warming. In the fall of 2007, Dr. Ed Rayburn, extension forage agronomist at WVU, reminded me that an increase of organic matter in the soil means that carbon dioxide (CO2) is being drawn from the air into the soil. He kindly agreed to calculate the rate of carbon sequestration in the pastures of West Wind Farm.
Our average organic matter in 2002 was 4.1 percent, in 2004 it was 7.0 percent, and in 2007 it was 8.3 percent. According to Rayburn’s calculations based on a 2-inch deep sample, over five years (2002-2007) we had sequestered 15 tons of CO2 per acre or four tons of carbon per acre.
During 1987-2007, we applied no chemical fertilizers, herbicides, or pesticides. We believe this policy increases the biological life in the soil and increases the rate of carbon sequestration. All manure was deposited in the pastures, thus minimizing methane emissions. For nitrogen we relied on clover, minimizing the formation and emission of nitrous oxide. Furthermore, according to the British Institute of Grassland and Environmental Research (as reported in Stockman Grass Farmer, May 2008), “Incorporation of legumes into a pasture would dramatically cut methane emissions.” (Probably that means methane emissions from enteric fermentation.) During 2000-2008, we practiced daily rotational grazing on our best pastures and two to three day rotations on lesser pastures. Thus we had a pulsing effect with each rotation – utilizing photosynthesis to pull CO2 into the plant and then into the roots, which partially died following each rotation, leaving decaying roots that became organic matter.
Carbon sequestration in well-managed pastures has tremendous potential for fighting global warming. Each of us who practices grass farming could benefit financially from a well-designed carbon trading system. The United States and the world could benefit, as well. Yet three obstacles impede development of this potential. I believe the American Grassfed Association could help with each of these.
First, I believe we need a standard method of measuring organic matter and thus the carbon in the soil. Questions include the depth at which a soil sample should be taken and the method of chemical analysis used to test the soil sample. Aerial photography is used to estimate carbon sequestration by trees, but I do not believe that method is applicable to grasslands.
In March I attended the annual meeting of the North East Pasture Consortium and urged the U.S. Department of Agriculture’s Agricultural Research Service (ARS) and university scientists there to research and develop the most effective and economical method of assessing carbon sequestration in pasture lands. To the best of my knowledge, no scientist or institution has acted on this request.
In May I attended the five year planning meeting (in Denver) of three ARS national programs: climate change, soils, and air quality. As an invited stakeholder, I made the same request there. These three national programs will for the next five years be combined into one called “climate change.” I believe it is possible that this National Program on Climate Change may act on my request, but an appeal from the American Grassfed Association would certainly be important reinforcement. Requests as an organization or from individuals should be addressed to: Charles L. Walthall, Ph.D., National Program Leader, Global Change, Air Quality, & Soils, Natural Resources and Sustainable Agricultural Systems, 5601 Sunnyside Ave, Room 4-2282, Beltsville, MD 20705-5104.]
Second, the general news media have created a public perception that the only way to pull CO2 out of the air is to plant more trees and preserve existing forests. Members of the scientific community that I have encountered seem to think trees are most important and also no-till farming to a lesser extent. Furthermore, many seem to think that cattle produce so much methane and nitrous oxide that the net effect is an increase in greenhouse gasses in the atmosphere. Some even advocate that all of us should become vegetarians. Even the National Geographic in its Climate Connection series on NPR produced and ran a piece praising Guatemala for transforming cattle ranches into newly planted forests.
I have nothing against forests, and I favor building houses of wood so as to sequester carbon for very long periods. However, the world is crying out for food. We grass farmers can produce delicious and healthful food – especially from ruminant animals - and sequester large amounts of carbon at the same time.
I hope that AGA will help to publicize the multiple benefits of grassfed meats. Of particular current interest is the predicament of many Midwest grain farmers that their fields were too wet to plant on time. If they had established grass on at least part of their farms, those fields would now be covered and green and they could be feeding some happy cattle right at the home farm. Multiple years of rotationally grazed pastures would sequester carbon into the soil and that high-carbon soil would be able to absorb more water when it rains and also hold more moisture when rain is scarce. Floods will cause much less soil erosion (and river silting) from grass-covered pastures than from bare fields.
Of immense long term interest is the high use of fossil fuels and chemicals in the production of conventional grain fed meats compared to grassfed meats. The June 2004 issue on National Geographic shows a handsome steer that needed 283 gallons of fossil fuel equivalents to finish. A recent list/serve email states that a Minnesota grass farmer used 0.5 gallons from birth to finish a steer!!!!
Third, we all, including AGA as an organization, need to communicate effectively with U.S. Congress, as it drafts next year’s carbon trading or carbon tax laws, in order that grass farmers will be financially rewarded for sequestering carbon.
NOTE to all grass farmers. If you are not already testing for organic matter in your pastures, please do start this year. It is the year-to-year increase that measures carbon sequestration.
For more information, contact Martha Holdridge, martha at westwindfarm dot biz. The farm’s website is www.westwindfarm.biz.
See also the map of measured soil carbon change.