Cycling nutrients

Erik Marcus points out that Michael Pollan’s new website includes the following claim:

A truly sustainable agriculture will involve animals, in order to complete the nutrient cycle, and those animals are going to be killed and eaten.

I was planning on addressing this point after getting to the point where he makes it in The Omnivore’s Dilemma, but this seems to be another good occasion for doing so.

I should begin by saying that I’m not an ecologist. I’m not going to claim to know definitively whether Pollan is right or wrong. However, he doesn’t provide evidence, so I’ll write a little bit about why I’m not convinced. If you know more than I do, I’d be interested to hear about it.

First of all, there are a number of successful examples of veganic (or vegan organic) farms, which keep no domesticated animals and use no animal inputs. Instead of animal manure, these farms use plant-based fertilizers, such as mulches and compost. The Veganic Agriculture Network claims that plant-based fertilizers are more efficient:

In fact, it would be more efficient to directly use the fodder to fertilize the soil than to feed the animals, collect the manure, compost it, transport it, and spread it on the soil.

They don’t provide any evidence for this claim, so it’s fair to treat it with some skepticism.

Now, most organic farms aren’t vegan organic, but there are some successful examples. Take, for instance, Honey Brook Organic Farm in New Jersey, which claims one of the largest Community Supported Agriculture (CSA) programs in the United States. It must be acknowledged that Honey Brook’s crops don’t include many protein-rich plants. However, the veganic Janlau Farm in Quebec grows soy, wheat, flax, and buckwheat.

I think that when Pollan talks about the need for animals to cycle nutrients, he’s drawing on his experience at Joel Salatin’s Polyface Farm, which provides what he says in The Omnivore’s Dilemma “looks an awful lot like the proverbially unattainable free lunch” (127). Indeed, it is the chickens that Pollan credits with applying nitrogen to the pasture.

These chickens aren’t simply living off the pasture, though. They also eat feed corn that Salatin buys from a neighbor who “might be using atrazine” (132). That is to say, it isn’t sustainable organic corn, but the bad stuff Pollan writes about in the first part of the book. It’s not at all clear to me that the fossil fuels used to grow that corn couldn’t more efficiently be used to grow plant-based foods.

As I wrote above, I’m interested to hear what you know. If anybody has heard Pollan further explain his claim about needing animals to cycle nutrients, I’d be interested to hear about that, too.



  1. x said

    Good points. Even if we, only for the sake of argument, set your points to the side we can object further to Pollan by pressing him on HOW MANY animals he thinks agriculture must necessarily involve (for supposed manure reasons)? How much manure is needed and how many animals are needed to produce it?

    Won’t the numbers be far, far below the current levels? If so then very much animal consumption still can (and should) be abolished. Furthermore, it is possible to get manure from animals that aren’t also killed and consumed. There might be technical and economical issues but not impossible nor incompatible with sustainability.

    • Adam Merberg said

      In fairness to Pollan, I have heard him say that people will need to eat a lot less meat if they’re only going to eat the kind he considers responsible.

  2. […] that would serve nobody’s interests—except those of our common enemy: animal agribusiness. Link. Spread the […]

  3. Lisa said

    There’s plenty of manure available from horses, which we don’t routinely kill and eat. I call bullshit on Pollan!

  4. […] In the CBC segment, Pollan comes in twice, from about 20:28 to 33:21 and at the end from 47:35 to 51:40. (Be advised that the two interviewees in between Pollan’s segments are anti-civilization activist and The Vegetarian Myth author Lierre Keith and a guy who doesn’t think we can distinguish between killing animals and killing plants). Pollan essentially rehashes some of the arguments for meat-eating that he made in The Omnivore’s Dilemma. I much prefer responding to printed text instead of audio, so I’ll address most of his points when I get to them in the book. (He did make some comments about needing animals to cycle nutrients, a topic I wrote about yesterday.) […]

  5. Andy D said

    I’m thinking of an animal that is extremely abundant, produces tons of manure-able wastes, and is only rarely killed and eaten. Can you guess which animal, Michael Pollan?

    Not that it’s obvious this is a sound choice for agriculture–there are public health problems if done improperly–but it’s something that appears to’ve been successfully practiced:

  6. bill said

    Let us not forget that humans are also manure-producing factories. Imagine how much nice compost and fertilizer we could make if we developed better ways for collecting our urine and bowel deposits.

    Sewage treatment plants serving urban centers could produce tons of usable manure IF humans could be trained not to flush all kinds of chemical contaminants down the drain to foul up the usability of the humanure. Once the humanure is collected from the settling tanks, it would sent to a large-scale composting site (or used onsite), mixed with a carbonaceous substrate (perhaps sawdust from various tree processing operations) and allowed to transmute into a high quality pathogen-free compost product. The highly nitrogenous effluent from the sewage treatment plants could be poured onto huge mounds of wood chips or chopped hay, helping to achieve the right C/N ratio for microbial activity and conversion into high quality pathogen-free compost product.

    Also, there are other options for collection of this material like composting toilets and urine collection tanks which would eliminate the processing activities of the sewage treatment plants. Newly constructed low and high occupancy buildings could be built in such a way as to make the collection of humanure and urine highly efficient. A woody substrate would be added to the humanure onsite allowing the compost process to begin before its removal from the collection chambers.

    Also, needless to say, all cities (not just hipster cities like San Francisco) should be doing roadside collection of food scraps from residences and commercial establishments. There is absolutely no excuse for restaurants, supermarkets, and individuals acting on their own, to be tossing all those nutrients into the dumpsters.

  7. […] the comments of my last post on the subject, Andy D and bill suggested using human manure, or humanure to fertilize crops. I don’t know enough […]

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