Friday, August 29, 2014

The Polyculture Project.

Conventional meat production has been (justly) criticized for the strain it puts on the environment and the deplorable conditions in which animals are kept. However, there is an alternative to conventional farming. Diversified, pasture-based farms, also called polycultures, work with the land such that the farm becomes integrated into the natural ecosystem. Multiple species of animals are raised together along with crops that can be used for animal feed and for human consumption. Overall, this type of farming provides many environmental benefits and a higher quality of life for the animals than conventional farms.

A criticism of polyculture farming is that it isn’t productive enough to meet the needs of our population, and thus, meat could only ever be a small part of a sustainable food system. Although often repeated, I have rarely seen this statement quantified, which has led me to ask the following question.

How much polyculture farmland would it take to produce enough meat to feed the US population?

Answering this question requires two types of data: the amount of meat we need for everyone in the US and the amount of meat, per acre, produced on polyculture farms. The USDA and FDA collect and distribute vast amounts of data on the productivity of US farms, but I couldn’t find anything on the productivity of pasture-based, diversified farms. So I set out to collect the data myself.

I first reached out to the farm where I currently get my meat: North Mountain Pastures (NMP), a polyculture farm in Pennsylvania. My family has been part of their Community Supported Agriculture (CSA) program for several years now. Every month, we get a box of meat with a variety of cuts from a variety of animals. The farm is run by Brooks and Anna Miller, who graciously contributed to this project.

Brooks and Anna put together this table of their farm’s output in 2013, which includes all of the animals they raised and the edible pounds of meat typically provided by each animal. The total weight they compute is consistent with a rough estimate based on the amount of meat supplied through their CSA. Brooks and Anna also calculated the acreage of their farm and the land required to produce some additional grains they feed their chickens and pigs. Dividing the total number of pounds (49,855) by the total acreage used (114), gives an annual output of 437.33 pounds of meat per acre.

The other key piece of data is the amount of meat required for the entire US. The USDA recommends that typical adults get about 6 oz of protein each day, which is 0.375 pounds (see MyPlate for more info). For this analysis, let’s assume that all of the protein comes from meat. Throughout a whole year, we would need to produce 42 billion pounds of meat to feed all 308 million Americans their recommended 6 oz. of meat every day. Americans actually consume about 52 billion pounds of meat each year (Earth Policy Institute).

Assuming the productivity of North Mountain Pastures farm, we would need just under 100 million acres of land to produce 42 billion pounds of meat each year and 119 million acres to match current demand for meat.

Those are such big numbers that it’s hard to interpret them without some context. So, let’s compare them to the amount of land we currently use for grazing. According to the USDA (as cited by the EPA), the US devoted about 600 million acres to animal grazing in 2007.

That means we could produce enough meat for the entire US population by converting 16% of our current grazing land to polyculture farming. We would need to convert 20% to match current meat demand.

That doesn’t seem like a lot of land at all. In fact, it seems like diversified farms could actually reduce the amount of land we devote to meat production without reducing the amount of meat people eat. Now, that doesn’t necessarily mean that meat is totally sustainable. There are other environmental impacts we should consider, such as water usage and carbon emission. From the perspective of land use though, diversified, pasture-based farms can provide more than enough meat without requiring any additional land.

If people choose to get less of their protein from meat, it would further lessen the land burden of raising animals. For example, North Mountain Pastures also produces eggs, which we did not include in their meat production numbers. Fish, nuts, seeds, and legumes are also high in protein and can serve as alternatives to meat. However, if sustainability is the goal, we would need to consider the relative environmental impact and scalability of obtaining these other foods to that of meat raised on polyculture farms.

Another benefit of diversified, pasture-based farming is that it hasn’t yet been fully optimized. Farmers and scientists around the world are working on advances that can boost efficiency and lessen the environmental impact of raising animals for food. At North Mountain Pastures, they are working with grain farmers who use no-till agriculture and other ecofriendly methods, exploring ways of reducing off-site feed, and adding an orchard. In a much broader effort, the Savory Institute is devoted to restoring badly managed grazing land and promoting ecologically-sound land management. If we actually wanted to convert current grazing land to polyculture farms, the Savory Institute’s research could help bring the productivity of marginal land closer to a farm like North Mountain Pastures. Additional improvements, as well as more widespread adoption, are also likely to lower the cost of producing meat in this way, a savings that can be passed on to the consumer. Currently, members of the NMP CSA pay about $8 per pound for their meat.

One other potential barrier to producing all our meat on polyculture farms is that we would have to change the way we eat meat. North Mountain Pastures raised 7 different animal species with a wide range in the number of animals of each species. For example, they raised only 12 cows and 10 goats but 240 turkeys and 5200 chickens. To take advantage of a diversified farm requires that we diversify both the types of animals and the cuts of meat we that we regularly eat.

For this analysis, I’ve assumed that any diversified farm could be as productive as North Mountain Pastures. Without any additional data, it’s hard to know if this assumption is reasonable. I will say that I didn’t know how productive NMP would be when I approached them about this project, although that doesn’t necessarily mean that their productivity is typical. And productivity can vary a lot depending on the location of the farm. That’s why I would like to expand upon this study to include as many polyculture farms as I can find. That way, I can better quantify the productivity and scalability of polyculture farms, assess additional environmental concerns, and help develop a pathway to a food system that produces meat without destroying the environment or abusing animals.

It’s a lofty goal and one that I can’t achieve on my own. If you, or someone you know, has data on the productivity of a polyculture farm, please consider sharing it with me. Together, we can turn the polyculture project into a polyculture solution.

Note: This material was originally presented at the 2014 Ancestral Health Symposium. I am so grateful to have had the opportunity to participate in this terrific event and for all of the interest and feedback I received from my fellow attendees.


  1. I think productivity of existing polyculture farms, while interesting, may not be the key piece of data. If we're looking at scalability, we have to confirm the availability of 120M acres of land that has similar potential to be productive as NMP (or the mean pc farm). Is there an estimate of the total land currently devoted to pc farms? How many orders of magnitude short of the 120M acres is it? I suspect that existing pc farms have self-selected for productive locations, hence the questions about the ability to scale out.

    To the potential benefit of being pro-sustainable-approach, you've left out fish from the equation. Very rough squinting at suggests around 1B lbs of wild halibut and salmon harvest from around Alaska per year (though now that I've checked back, that's not a huge dent in the 42B we'd like to be eating). There should be other wild sources as well, though ...

    I will add that the $8 per pound aggregate figure feels pretty high, certainly as a number for the general population. Even making a large salary, sockeye salmon is the most expensive thing we tend to buy (at $10-12 per lb from Costco).

    1. I agree that scalability is the key unanswered question, which is why I am looking for more farmers to contribute data. I was able to find a report from the USDA on grazing land in 2002, published in 2012 (see links below), in which they state that 62 million acres of grazing land is considered prime land for grazing. That's about 2/3 of what we would need using polyculture farming. If the remaining grazing land is less productive than a typical mid-Atlantic farm, then we would need more land than I have estimated. But, given how much total acreage we devote to grazing, it seems like we could make up for this efficiency without using additional land for raising animals.

      I don't have a good estimate of the number/acreage of polyculture farms in the US, but I am certain it is quite small compared with conventional animal farms. Also, while polycultures likely do self-select for productive regions, I'm sure there is much more "prime" land available than is currently used for polycultures.

      Full report site:
      Chapter on grazing land:

      As for seafood, that's not my area of expertise. However, after speaking with some sustainable seafood folks, I can tell you that the biggest problem with seafood is that sustainable habitats cannot produce as much seafood as we would want to eat. In other words, if we all wanted to consume 6 oz of fish every day, those habitats would collapse.

      Yes, the meat is definitely more expensive because the true costs are folded into the price. However, as I said in the post, I think the more widely we support and adopt these practices, the cheaper they will get.

  2. How much farmland would it take to produce enough fruits and vegetables, eggs, milk and cheese to feed the US population?