Last summer, I published a post attempting a crude analysis of the inputs and outputs at Polyface Farm. My rough calculations led me to speculate that Polyface Farm may require more calories in grain and soy than it produces in meat, and Joel Salatin seems to have confirmed this when I asked him last month. This analysis has received a bit of attention in various corners of the internet, so I think it’s worth talking about what these numbers might tell us (or not tell us).
On the one hand, I can’t quite endorse the conclusions of Ginny Messina, who wrote in her review of Lierre Keith’s The Vegetarian Myth that the numbers “suggest that there is no such thing as truly sustainable meat production.”
To say that something is sustainable means that it can be continued indefinitely. Comparing the caloric inputs and outputs of a farm doesn’t really tell us anything about whether that is the case. Moreover, it’s important to recognize that production of plant-based crops requires fossil fuels and fertilizers that are in limited supply, so we don’t have “truly sustainable” vegetable production either.
That’s not to say that the numbers don’t have any relevance to The Vegetarian Myth. Indeed, Lierre Keith cites The Omnivore’s Dilemma extensively, and offers a great example of how one might be misled by Pollan’s work. Keith writes extensively about the environmental damage done by grain agriculture. In her conclusion, she asks,
So here are the questions you should ask, a new form of grace to say over your food. Does this food build or destroy topsoil? Does it use only ambient sun and rainfall, or does it require fossil soil, fossil fuel, fossil water, and drained wetlands, damaged rivers? Could you walk to where it grows, or does it come to you on a path slick with petroleum?
Everything falls into place with those three questions. Those annual monocrops lose on all three counts, unless you live in Nebraska, where it “only” fails the first two.
The reader is to contrast a grain-based diet with one based on pastured animals. Keith writes, “Cattle on pasture in my [New England] climate can easily be sustainable. Joel Salatin is certainly proving that.” We’re to believe that Salatin’s meat passes Keith’s three-question test.
Based on Pollan’s numbers in The Omnivore’s Dilemma, Keith calculates that ten acres of pasture farmed Polyface style can produce enough calories to feed nine people. That might sound impressive at first, but it’s decidedly less so when you consider that this would require grain that could feed even more people. Bringing that feed grain to Polyface Farm depletes more topsoil and requires more fossil fuels than growing and harvesting grain (in smaller amounts) to feed directly to people. More generally, any bad things one might say about grain production will apply even more strongly to the Polyface meal than to a meal of grains with comparable caloric content, and thus support a conclusion opposite the one that Lierre Keith reaches.
However, it oversimplifies things to simply compare calorie content. A meal of corn, soy, and oats would not be nutritionally equivalent to a Polyface meal of similar caloric content. The former meal would, for example, be higher in carbohydrates, lower in protein, and entirely void of vitamin B12. Thus, one might conceivably be able to argue that Polyface-style farming is our best option for producing protein or vitamin B12. (I have no reason to believe that either of these is actually true, and I would be surprised if either were.)
Of course, it makes little sense to consider nutrients individually. A much more meaningful comparison would look at the environmental impact of two nutritionally adequate meals. (There are those who will argue that a meal containing grains can never be nutritionally acceptable, but that is a strictly nutritional question, to be distinguished from the environmental considerations at hand.)
In spite of these limitations, I would emphasize that I don’t think these numbers are entirely worthless. For one, they suggest that a more careful analysis is necessary before Polyface Farm can reasonably be used to support arguments for meat production on environmental grounds. On a broader level, the numbers should be a warning against false solutions. We should be alarmed to see Polyface compared to “the proverbially unattainable free lunch” (as it is in The Omnivore’s Dilemma), and we should ask questions when we see it presented as an alternative to monocultures (as it is in the movie Fresh and Keith’s The Vegetarian Myth).