People and Place

The standard criticism of organic agriculture is that it could never feed the world. Because crop yields are lower under organic systems, they require more land to grow the same amount of food.

Here’s an example from a December 2006 editorial in The Economist:

Farming is inherently bad for the environment: since humans took it up around 11,000 years ago, the result has been deforestation on a massive scale. But following the “green revolution” of the 1960s greater use of chemical fertiliser has tripled grain yields with very little increase in the area of land under cultivation. Organic methods, which rely on crop rotation, manure and compost in place of fertiliser, are far less intensive. So producing the world’s current agricultural output organically would require several times as much land as is currently cultivated. There wouldn’t be much room left for the rainforest.

As The Economist trumpets, the green revolution produced dramatic increases in grain yields in many parts of the world. Cornell University professor of ecology and agriculture David Pimentel attributes approximately 40% of the increase in yields to plant breeding and 60% to inputs of fossil-fuel energy, fertilizers and pesticides. (Science, subscription only)

But conventional farming practices have contributed to mounting ills as well - soil erosion, biodiversity loss, fossil fuel depletion, greenhouse gas emissions, offshore dead zones, groundwater pollution, farmworker poisonings, loss of local autonomy, concerns about toxic loads among eaters, and so on. By these measures, organic farming is generally considered a better alternative. And so the debate turns to the question of yields.

The latest findings come from researchers at the University of Michigan, who weigh in with a paper that compiles data from over 90 published studies on crop yields from around the world. They conclude that in developed countries, organic systems achieve about 92% of conventional production levels, and in developing countries, organic systems perform even better.

The most notable studies in favor of organics include two direct comparisons: the Rodale Institute Farming Systems Trial (studied here), which is the longest running conventional-versus-organics test in the United States, and the Rothamsted Research Classical Experiments (discussed here), which have an unbroken history of over 150 years in England. The former finds that for corn and soybeans, yields are nearly equal; the latter finds the same for wheat. On the other side of the ledger, a 21-year study of farming systems in Central Europe (Science subscription) finds that, for a variety of crops, yields averaged 20% lower under the organic system. In fact, “many long-term studies have shown a 10 to 40% organic yield deficit,” write Hudson Institute researcher Alex Avery and his colleagues (Science subscription).

Suppose organic yields are indeed lower. Does that mean, as The Economist and others assert, that more land would be required to grow the same amount of food? Not so, say the researchers of the Central European study, cited above. Responding to a letter (Science subscription) that levels this charge, they maintain that those types of bushel-to-bushel, acre-to-acre comparisons are misleading. The difference is that organic systems maintain the fertility of the land on which they are cultivated. Conventional systems, on the other hand, have experienced massive loss of arable land to erosion over the last few decades. On a constrained land base, organics will outperform conventional systems over the longer term.

Given this brief suvey of the debate, let’s look back at that statement by the venerable Economist: “Producing the world’s current agricultural output organically would require several times as much land as is currently cultivated.” Several times. Patently ridiculous.

In closing, let’s turn back to Mr. Pimental, whose authority in the calculation of soil and energy flows may be unparalleled. He’s in the midst of a debate with Mr. Avery, mentioned above:

Avery et al. imply that I reported that all U.S. and world agriculture could be grown organically without commercial nitrogen fertilizer. They are incorrect–I never said this in my review, nor have I ever said this in any of the more than 500 scientific papers that I have published. … The world has a severe food shortage problem; the World Health Organization recently reported that 3.7 billion people are malnourished. … Certainly, we need sound genetic engineering, as well as soil and water conservation, to increase the yields of our food crops and make agriculture ecologically and economically sustainable.

And so, even an even-handed analyst like Mr. Pimental is skeptical of the notion that organics could feed the world. Or is he? For if we look closer, we find that he has relied on an all too common assumption.

Mr. Pimental conflates the ecological question of growing enough food, which we’ve been examining in this post, with the problem of hunger. Those issues are related, of course. But strong arguments have been made that hunger is at least as attributable to politico-socio-economic factors – what University of Toronto professor of political science Thomas Homer-Dixon calls structural scarcity.

More to come.