The NPR Planet Money podcast just ran an interesting episode about the challenges a farmer started having with bald eagles when he went organic and started raising chickens outdoors. It's a nice story, but I want to take a minute to correct a subtle (but important) message about organic production promoted in the podcast that is widely mis-understood. It has to do with the nitrogen cycle. Here is Planet Money:
Here is the problem - the "chemical fertilizer" wasn't actually replaced (at least not fully).
All farms, if they want to be productive, need fertilizer, and they need nitrogen in particular. There is ample nitrogen in the air, but it is not in a form that is available to most plants or animals. Up until about a hundred years ago, we had to get the bulk of our nitrogen from microbes that grew alongside legumes that "fix" the nitrogen in the air and make it available to plants. Animals would then eat the plants, use some of the nitrogen, and then excrete some of the nitrogen in their manure. This is why manure is a great fertilizer - it contains residual nitrogen. But, here's the main point: the nitrogen didn't come from the cow, pig, or chicken. It came from the microbes in the soil and made it into the animal via the plant.
Then, along came Haber and Bosch. They figured out a way to get nitrogen from the air. This greatly increased the amount of nitrogen available, increased crop yields, the number of animals we could feed, and ultimately the human population. Here is Thomas Hager in the fantastic book The Alchemy of Air on the effects of this extra nitrogen:
So, what does any of this have to do with the NPR podcast? The farmer (and the reporters) apparently believe they have escaped the use of "synthetic" fertilizer brought about by the Haber-Bosch process because the farmer's fertilization now relies on manure from chickens. But, where did the nitrogen in the chicken manure come from? The answer is that it came in via the feed the farm bought and brought in from another farm.
Maybe the farmer bought organic corn to feed his chickens. That solves the problem, right? Not exactly. Your see, the organic corn farmer who sold our organic chicken farmer corn undoubtedly used fertilizer. There is a very good chance that this fertilizer was some form of manure. Yet (and this is a very important point), organic rules don't discriminate whether manure comes from an organic or non-organic fed animal. Because there are many, many more non-organic animals, chances are that the manure came from an animal fed non-organic grain. Where did the nitrogen in that non-organic grain and then manure come from? Haber and Bosch.
Thus, even assuming that organic chicken feed was used, there is a very high probability that the nitrogen in the chicken manure that was used on our organic farm featured in the NPR story came from corn that was fertilized with manure that came from a cow or pig or chicken that was fed corn that was fertilized using nitrogen made available via Haber and Bosch.
So, despite what is implied by the journalists (and perhaps even believed by the farmer), we haven't returned to some kind of "natural" nitrogen cycle. We've simply found ways of importing "synthetic" nitrogen into a system that makes it look "natural." This academic paper looking at French farms, for example, calculated that organic farms strongly rely on non-organic farms for their nutrient flows finding on average, 73% of phosphorus, 53% of potassium, and 23% of the nitrogen used in the organic farms in their studies was imported from conventional, non-organic farms via processes like the one I described above. As one writer put it:
Now, one could avoid all this by requiring organic producers to use only manures from organic animals fed organic feed. However, I seriously doubt there is enough available nitrogen from this "natural" system to support the present size of the organic market. As the organic market grows, this likelihood becomes even more remote. Indeed, if one wants large scale organic, it almost certainly implies (given the current population) the need for large scale non-organic. All that life-supporting nitrogen has to come from somewhere. Until we find a better way, right now it is coming from Haber and Bosch and is smuggled into organic agriculture via animal manure.