History Professor James E. McWilliams’ recent doubled-barreled attack on sustainable livestock production and the local food movement in general is so contradictory and full of factual holes, it’s tough to know where to begin to pick it apart. But it must be picked apart, since it has appeared in the New York Times and subsequently several other newspapers around the country, including the Star Tribune. That gives it the kind of (undeserved) credibility that can’t be ignored.

Fortunately, Virginia farmer Joel Salatin has done an excellent job of doing a point-by-point deconstruction of McWilliams’ argument that sustainable farming is actually bad for the environment. Salatin’s piece does a wonderful job of combining his own practical experience as a livestock producer with the general, well-known scientific/economic facts at hand. And it’s that latter point that is perhaps the most troubling about McWilliams’ screed: his misstatements aren’t just off by a little in the facts department—they’re off by a lot.

Here’s one example: he claims right out of the chute that “grass-grazing cows emit considerably more methane than grain-fed cows.” McWilliams then goes on to use that as one of the major reasons we should not look to farming methods such as pasture-based livestock production as a basis for a more sustainable food system. Large-scale confinement of livestock may be inhumane, McWilliams maintains, but environmentally it’s preferable to pasture-based systems.

As Huck Finn would say, that’s quite a stretcher. The fact is, research conducted by the USDA’s Agricultural Research Service found that total emissions for the greenhouse gases methane, nitrous oxide and carbon dioxide were 8 percent lower in systems where dairy cows were kept on pasture. When fields were converted from row crops to perennial grasslands for grazing, annual carbon sequestration levels climbed from zero to as high as 3,400 pounds per acre, according to the research. Overall, a well-managed dairy herd kept outdoors year-round had a 6 percent smaller carbon footprint compared to its confinement counterpart.

This research takes a big-picture look at the whole greenhouse gas emissions issue by going beyond what comes out of the back end of a cow at any given time and examining the entire system over the length of a growing season—from what and how the feed is raised for the cows to what happens to their manure afterwards. And isn’t it the long-term impacts that matter in the real world?

“The carbon sequestration benefits really add up,” ARS agricultural engineer Al Rotz told the publication Agricultural Research. “When farmland is transitioned from rotated crops to perennial grassland, you can build up lots of carbon in the soil and substantially reduce your carbon footprint for 20 to 30 years.”

The other benefits of such a transition are significant as well. When cows were kept in barns year-round, sediment erosion from growing corn and alfalfa for feed averaged 2,500 pounds per acre. But when cows were allowed to get their feed from perennial grasslands, erosion dropped 87 percent. Phosphorus runoff dropped from 57 pounds per acre to 44 pounds when cows were put on pasture.

These research results came out in May 2011, giving McWilliams plenty of time to correct his facts for an April 2012 newspaper commentary. (He’s also apparently chosen to ignore the elephant in the room when it comes to large-scale livestock’s environmental unsustainability: the Gulf of Mexico’s Dead Zone.) The USDA, which has long promoted confinement livestock production, should be applauded for finally letting the science on sustainable animal farming speak for itself.

If only Professor McWilliams was as open-minded.