Cows and Climate

Fall 2014

By Joann S. Grohman

I listen to many talks by highly qualified scientists and others deeply concerned about our future, as well they might be. Some are concerned about climate change, others about starvation. In their summary remarks – I wait for it: Their suggestions for how we can mitigate disaster always include a well-meant suggestion that we eat less meat on the grounds that to do so will liberate more resources to grow human food. Few seem to question this supposed cause and effect.

Countering Cows’ Negative Press

Cattle are not competing with humans for grass, their real food. The fact that corn and soy are being fed to animals reflects the artificial circumstances in which the animals are being kept. Cows are being criticized for making inefficient use of what is not their natural food. This use of land and feed is part of the agribusiness/CAFO (Concentrated Animal Feeding Operation – “factory farms”) complex. A more courageous suggestion would be to banish CAFOs and feed animals locally on their natural food. This would eliminate both competition for grain and the CO2 burden associated with its commercial production.

Furthermore there is no shortage of land. An artificial competition has been set up leaving animals, especially cows, as offenders. There is no shortage of land or resources for local food production, although restrictive zoning in the United States and land grabs in many areas inhibit current use by local, diversified growers. Food production in an integrated small farm system can be far more productive per acre, since all the different parts support each other, plus the system benefits from the hand of the owner. As they used to say, “The eye of the master fattens the livestock.” The cow’s manure goes to feed the soil instead of causing pollution. This feeds crops, which feed humans and other non-ruminant animals.

Simon Fairlie, in his wonderfully readable and important book Meat, the Benign Extravagance, devotes an especially witty chapter to the water requirements of cows. Fairlie spent an entire year trying to find the basic scientific studies that would support certain allegations – such as that cows use enough water to float a battleship, or that a cow uses 25,000 gallons of water for every pound of meat. Some misconceptions about cattle seem to have originated with some germ of fact on which tottering accusations are perched; but for these water claims, there is nothing. As a reality check, Fairlie gives us the life story of his steer, Bramley. For a year and a half on his acre of grass, Bramley was satisfied with his tub of 10 gallons of water per day. Most of this water Bramley used to anoint the grass. The rest left his body as vapor or was incorporated into his flesh.

In 2009, a United Nations Food and Agriculture Organization (UNFAO) paper entitled “Livestock’s Long Shadow” published the statement that livestock accounted for 17 percent of CO2 contributions to the atmosphere – more than the contributions from transportation. This claim was soundly refuted by qualified experts within hours of publication – but too late. The claim appears only in the introduction to the publication and is not supported within the text of the paper itself, yet reporters seized upon and trumpeted it around the world. It has become an unchallenged meme. For reasons best known to himself, the author of the introduction bundled everything from the manufacture of the tractors that produced the animal feed, the milling and transportation of the feed, and everything else related to livestock production into their fossil fuel account. In the case of transportation, he counted only direct use of fossil fuel when driving. This exaggerated fossil fuel use by livestock has no validity, even within the agribusiness model of livestock management. And it bears repeating: The natural diet of cattle is grass.

And then there’s methane, a more potent global warming gas than CO2. Methane is a carbon compound produced during anaerobic fermentation, a process that occurs only in the absence of oxygen. The cow’s rumen is a fermentation vat in which bacteria break down cellulose from plants and use the liberated carbohydrates as an energy source to build complete protein. Any energy left over will be liberated as methane. Periodically the cow belches and releases the gas. Fermentation is the process by which grass is converted into the world’s most perfect food, milk. Far from congratulating the cow on her magic, reporters presuming that the methane gas left through the cow’s rear exit made this the subject of endless humor. Vegetarians and others immediately blamed cows for contributing to climate change with their methane emissions. Cows and all living things that subsist solely on plants produce methane. This is the way nature has always worked. It has never unbalanced the atmosphere.

Manure in the open air is not a source of methane. Again, methane is produced only in the absence of oxygen. When dropped on the pasture, manure is the natural source of fertility for the land. Many authors have assumed that methane is also produced on pasture or when manure is composted, but such is not the case; both occur in the presence of oxygen and are not sources of methane.

The Positive Contributions of Cows

So far, none of the negative misconceptions about cows have survived scrutiny. What about the positive contributions your cow can make? Whole books have been written about the special contributions of cows to humans from the beginning of civilization. Now people increasingly accept that a key contribution of cows is that they thrive best grazing on grass – which is important not just to cows but also to the planet.

Grass, the world’s most widespread crop, truly is amazing. All plants remove carbon from the atmosphere and incorporate it into their structures, but most plants, if bitten off, regenerate slowly or not at all. Loss of growing leaves is a severe setback. Trees sequester a lot of carbon in their leaves and trunks, but when the tree dies, most of that carbon will be released back into the atmosphere – more quickly in case of fire. The growth nodes of grass, however, are at the soil surface. When grass is eaten, a biochemical signal “tells” the plant to send up new leaf growth, resulting in denser turf. The more grass is eaten, the faster it grows and the more carbon it captures and stores underground in its roots. As grazing animals trample grass, it is pushed underground along with manure and urine, where it decomposes and its carbon feeds soil microbes. This property of grass depends entirely on the presence of herbivores. Without the nibbling, trampling and fertilization of herbivores, grass fails to function as this massive carbon sink. Grass without grazers dies above ground and loses its carbon back into the air.

Allan Savory has greatly expanded our understanding of the work of which grass is capable. Savory was born in what is now Zimbabwe to a long-established colonial family. He has devoted his life to rebuilding grasslands. Careful observation and a courageous willingness to move past older ideas (including his own) have enabled him to understand grass and its interdependence with grazers, predators and the soil. Working in Africa and the United States, he has demonstrated how desertification is initiated and reversed. Savory shows that grass must be encouraged by herbivores. To properly encourage grass, herbivores must graze in a dense pattern. Grass achieves its maximum turf-building response only under the grazing pressure of bunched animals, and then the animals must move on, leaving the grass to regrow. In the wild this absolutely depends on the presence of predators; otherwise the animals will stray apart in a random fashion and the turf-building effect is lost. It can’t be overemphasized: Grass, cattle and predators evolved together and are mutually interdependent. Soil fertility is the result of their alliance. This is the perfect example of ecological unity.

The capacity of grass to store carbon is well recognized, but its potential as a major factor in reducing atmospheric CO2 hasn’t been considered seriously, and sufficient experimental studies have not been done to accurately quantify its effect. It hasn’t even been thought capable of being involved in carbon trading. This is about to change with the work of the Marin Carbon Project – a research project initiated by a Marin County, California, rancher named John Wick. Like Savory, Wick discovered that removing livestock from his land and resting it had the reverse effect to what he was seeking. Both turf density and soil fertility diminished faster than had been occurring with livestock on the range. To try a new approach, he teamed up with one of the world’s foremost soil carbon sequestration experts, Berkeley bio-geophysicist Whendee Silver. She agreed to do the study despite considerable initial skepticism. Wick wanted a controlled study that would yield unassailable statistics. With the cooperation and support of other interested ranchers in the area, Wick spread dairy manure composted with straw a half-inch deep over several large test plots. Adjacent plots served as controls. After a year, core samples were taken to measure and compare soil carbon with samples taken at the beginning of the trial. At the end of the year, carbon in the treated plots had increased by a ton per hectare, not counting the carbon in the compost. Wick and Silver have now measured an additional ton of carbon per hectare per year without adding any more compost. This is new carbon in the soil, carbon that was removed from the air.

Carbon behaves like a sponge, so that the treated soil held three times as much water. Wick and the other ranchers also noted that the land could carry more cattle, an observation often noted by Savory, and that the land profits from the additional livestock.

Wick and Silver found with their core samples that this newly sequestered carbon moves downward to lower soil levels, where it remains in stable storage unless the soil is plowed. Using computer modeling, Silver’s research group asserts that if half of California’s rangeland were treated with compost in this way, in any given year as much atmospheric carbon as is emitted by California’s traffic could be removed from the air and permanently stored. Savory and others have claimed land restoration, improved air quality and increased agricultural productivity from planned grazing. The Marin Carbon project proves that by working with natural systems, our air and soil damage can be reversed with unexpected speed. Complete statistics on the project are available at

This is an incomparably important study. I hope we can now hear less about techno-fixes involving filling the sea with iron filings or building machines to put carbon down holes in the ground. The Marin Carbon Project proves that by working with a natural process, we can feed ourselves and reverse global warming – and we can all do this ourselves without waiting for someone to form a new government agency and hire contractors. We can save the world one cow and one farm at a time. If this seems too good to be true, bear in mind that it worked fine for millions of years, building topsoil that was many feet deep. Current practices of extractive farming reversed this benefit.

Far from being a destructive force, cows are the key to rebuilding air quality and soil fertility. Cows provide for us by completing the cycle of life on our own farms or on the rangelands of the world, turning sunshine into food of the highest quality, and taking excess carbon out of the air and putting it back into the soil where it is needed.

Carbon exists in five phases:

• in the atmosphere as carbon dioxide (CO2)

• in the biosphere as carbohydrates, i.e., plant material

• in the pedosphere (soil) in three states

• labile pool – Carbon from decaying plant material may oxidize and return to the atmosphere or may be fixed by microorganisms and stay in the soil.

• occluded light fraction – Carbon is trapped inside soil crumbs where it will stay for years unless the surface is disturbed, permitting oxidation.

• heavy fraction – Beneath the occluded light fraction, carbon is bonded to soil structure and is not available to microorganisms.

Carbon in the soil behaves like a sponge. With increased carbon, soil holds more water and thus supports more plant growth, which pulls more carbon out of the atmosphere, a feedback loop with positive effects for climate.

• in the lithosphere (solid earth), where carbon moves downward and occurs as crude oil, coal, diamonds or other carbonaceous compounds

• in the hydrosphere (oceans), where carbon is mostly in the form of bicarbonate ions and carbonic acid

About the author: Joann Grohman has farmed in California, Washington, Sussex, England, and now in Carthage, Maine. She is the author of Keeping a Family Cow (updated and published in 2013 by Chelsea Green).

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