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Synthesis/Regeneration 59   (Fall 2012)

Limits to agriculture

Small Is Bountiful

by Henry Robertson

In 2008 the South Korean conglomerate Daewoo took a 99-year lease on 1.3 million hectares of Madagascar to grow corn for the South Korean market. It was the largest of a number of deals between countries with large populations or arid land and countries that are poor or land-rich. China got access to land in Russia and the Philippines, Libya did a deal with Ukraine, Saudi Arabia with Indonesia, and Qatar with Vietnam. At least six countries have bought land in Sudan. Water rights often go with the land, even in dry countries like Mali and Sudan.

This new land rush—or food rush—isn’t always one-sided. Malaysia has palm oil plantations in Laos, where 15% of the country’s territory has been signed over to foreign interests. Sweden has bought 120,000 hectares in Russia. Brazil, one of the top emerging economies, is open to business from China and Saudi Arabia. [1] Estimates of the extent of this traffic run as high as 50 million hectares, equal to half the arable land in China. [2]

This is the endgame in a process of agricultural expansion and imperialism that’s as old as civilization. From the beginning of agriculture 10,000 years ago, farmers have exhausted their soil and moved on. Now that the world is full, the search for land has turned back on itself. There is nowhere left to go.

Testing the limits

David R. Montgomery tells the tale of land degradation and the quest for new soil in Dirt: The Erosion of Civilizations. [3]

Topsoil, a mixture of organic matter from above and minerals from weathered rock below, forms naturally at the geologically slow rate of inches per millennium. Bad farming can erode it at a rate of inches per decade. The global average erosion rate today is far lower (maybe a millimeter a year in developing countries, less in the US; it’s hard to measure) but still many times the rate of soil formation. [4] Virgin soils in the temperate and tropical latitudes are 1–3 feet thick. This is the desperately thin “skin of the earth” on which terrestrial life depends.

The global erosion rate today is many times the rate of soil formation.

Increased agricultural production goes hand in hand with population growth. This dynamic forced early farmers out of the fertile river valleys and onto erodible slopes.

Ways to preserve topsoil were known in ancient times: Rotate cereal crops with plants like clover, alfalfa, peas and beans (they didn’t know about nitrogen, but these are nitrogen-fixing legumes); allow cattle and sheep to graze and replenish the soil with manure. But the incentive to maximize production has always competed with good husbandry.

Large plantations have never been good for the soil. Absentee landowners, hired overseers and involuntary labor disregard the health of the land in the push to grow cash crops. The Roman farming estates called latifundia, together with the practice of plowing up and down slopes instead of across (contour plowing), ruined Italian soils. Rome turned to North Africa until the soil there was degraded too. Egypt became the granary of the empire. The Nile valley had the longest run of agricultural productivity on record until the Aswan High Dam opened in 1965. The dam withholds silt that should replenish the soil downstream, while six feet of water evaporate each year from the reservoir in the desert sun. Now the Nile delta is eroding and suffering salinization.

Large plantations have never been good for the soil.

After the Roman empire collapsed, a system of common fields with crop rotation and pasture evolved in Europe as a way to cope with depleted soils. Productivity remained low, due apparently to the ever-present pressure to maximize yields.

According to Montgomery, the enclosure of common lands that began in the late Middle Ages was a good thing up to a point. It allowed a farmer to keep enough land in pasture to ensure an adequate supply of manure. In the early modern period, however, landowners used enclosure to create large estates, arguing that they would increase productivity.

Simply letting the family cow poop on the commons would not do. The need for manure imposed an inherent scale to productive farms. Too small a farm was a recipe for degrading soil fertility through continuous cropping. Although very large farms turned out to mine the soil itself, this was not yet apparent—and Roman experience in this regard was long forgotten. [5]

The advance of agricultural science did not salvage the situation. “Crop yields at the start of the eighteenth century were not all that much greater than medieval levels, implying that increased agricultural production came largely from expanding the area cultivated rather than improved agricultural methods.” [6] Meanwhile, enclosure forced landless peasants onto the dole or into the industrializing cities. The European diet deteriorated.

Colonization, the biggest land grab in history, rescued Europe. Plantation agriculture for export back to Europe was favored. Colonists in the Americas, gazing at a horizon of seemingly endless fresh land, paid scant attention to soil fertility. The situation was worst in the American South, where slave plantations grew soil-exhausting tobacco and cotton. By the Civil War, the seaboard southern states were breeding slaves, not crops, for export westward, where planters were clearing their way through Alabama and Mississippi and into Texas to continue the same unsustainable practices.

In the late nineteenth century the westward push in the US continued, encouraged by a false gospel that intensive dryland farming was feasible west of the hundredth meridian. The eventual result was the Dust Bowl. [7]

In the era of limits

Today our species cultivates 1.5 billion hectares, an average of barely half an acre per person. World food production doubled in the second half of the twentieth century due to the Green Revolution of “miracle” crop varieties, chemical fertilizer, irrigation and, in the industrialized parts of the world, mechanized farming. Now this trend of rapidly increasing yields has ground to a halt.

Today our species cultivates barely half an acre per person.

We are up against planetary limits imposed by climate change and the overexploitation of fossil fuels, fresh water and soil. If the US is going to feed itself without fossil fuels, we cannot have vast industrial farms employing less than 2% of the population. The solution to the unemployment problem is farming—small farming. Agribusiness companies are cash-croppers like no Roman senator or southern slave master before them. They grow commodities, not food. Their corn and soybeans make ethanol, biodiesel and processed food-like substances.

There is another limit to agriculture—nitrogen fixation. Plants need nitrogen. The atmosphere is full of nitrogen but in the inert form of N2. The bond between those two atoms must be broken to make nitrogen available for use in the biosphere, but nature has only two ways to do that—lightning and the action of rhizobial bacteria on the roots of leguminous plants, which is why those plants had to be grown in rotation with other crops. As long as this was the sole means of getting nitrogen into the soil, the only way to feed a growing population was to expand the area under cultivation.

The artificial solution to this limiting factor is the Haber-Bosch process invented in Germany just before World War I. It breaks the N2 bond and combines nitrogen with hydrogen to form ammonia, from which fertilizer can be manufactured. This made industrial monocropping and twentieth-century yields possible. Instead of being in short supply, reactive nitrogen is suddenly everywhere, with grave consequences—further erosion, oceanic dead zones from fertilizer runoff, ground-level ozone (a precursor to smog), loss of biodiversity, and N2O, a greenhouse gas 300 times as potent as CO2. [8]

Haber-Bosch is also an energy-intensive process. It consumes 5% of the world’s natural gas production. Natural gas is a finite resource. It’s our primary heating fuel, an industrial fuel, and now—with new supplies and lower prices thanks to the destructive practice of hydraulic fracturing or “fracking,” which releases gas trapped in shale rock formations—the favored fuel for electricity.

Vaclav Smil, a renowned energy expert at the University of Manitoba, calculated that without Haber-Bosch we could not feed more than half the world’s population on present agricultural land. If he’s right, organic farming won’t save us because it relies on natural nitrogen fixation.

There’s plenty of evidence to the contrary, however, and Smil has admitted that he didn’t give leguminous crops their full due. [9] But it will take time to restore damaged soils, and Haber-Bosch fertilizers will be needed for as long as this takes. This is a reminder that we shouldn’t burn fossil fuels like there’s no tomorrow. Like any valuable, nonrenewable resource, natural gas should be conserved. It shouldn’t be burned in vast quantities for electricity when there are clean alternatives, or for unnecessary heating, or to manufacture junk to feed the insatiable maw of a growth economy that declares wasteful consumption a virtue.

The future is in the hands of small farmers interested in conserving their land.

Our species is on the knife’s edge. The future is in the hands of small farmers interested in conserving their land, and in the kind of plant breeding being done at The Land Institute in Salina, Kansas, to create perennial grain crops. Perennial prairie grasses have thick, deep roots that hold soil and moisture. Perennial cereals could halt the erosion that conventional agriculture accelerates.

The first task in feeding the world sustainably is to rebuild the soil. In the US this means reclaiming the land from industrial agribusiness and rebuilding agrarian communities.

Henry Robertson is an environmental lawyer and activist in St. Louis.


1. Cover story and accompanying articles, Guardian Weekly, Nov. 28, 2008; John Vidal, Food land grab “puts world’s poor at risk,” Guardian Weekly, Oct. 7, 2009; Claire Provost and agencies, Africa’s “water grab” threatens local communities, Guardian Weekly, Dec. 2, 2011.

2. Gilding, Paul, The Great Disruption, Bloomsbury Press, 2011, p. 83.

3. Montgomery, David R., Dirt: The Erosion of Civilizations, University of California Press, 2007.

4. Morton, Oliver, Eating the Sun: How Plants Power the Planet, Harper Perennial, 2009, p. 350.

5. Montgomery, pp. 96–8.

6. Id., p. 99.

7. See Timothy Egan, The Worst Hard Time, Houghton Mifflin, 2005; Jonathan Raban, Bad Land, Pantheon Books, 1996.

8. For more on this subject, see Oliver Morton’s excellent book on photosynthesis (and climate change), Eating the Sun, pp. 351–4; and Mark Lynas, The God Species: Saving the Planet in the Age of Humans, National Geographic Books, 2011, Boundary 3. This is not the place to excoriate Lynas for his strident insistence that all our ecological problems can be solved by technology alone.

9. Halwell, Brian, Can Organic Farming Feed Us All? World Watch Magazine 19:3, May/June 2006, http://www.worldwatch.org/node/4060

[22 aug 12]

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