David R. Montgomery's
DIRT:
THE EROSION OF CIVILIZATION

reviewed by

NATALIE BENNET

_________

Natalie is the editor of My London Your London, an independent cultural guide featuring theatre, gallery and museum reviews, and also blogs at Philobiblon, on history, culture, Green politics and all things feminist.

As a young undergraduate studying agriculture, soil science was not one of my favourite subjects. But I did pick up a sense that Australia was not so much farming as mining its soils: there was rising salinity along the breadbasket Murray-Darling basin; erosion from the impact of the hard-hoofed cattle and sheep; desert winds were sweeping away marginal lands being ploughed up for wheat.

It was only when, as a journalist, I visited a permaculture farmer, who went into the middle of a wheat field, yellow and crispy, ready to harvest, and with no appreciable effort pushed a spade into the earth, turning over dark, moist, hummus-rich soil crawling with earthworms that I started to grasp how alternative approaches to the industrial farming about which I had been taught might have a point. And that the soil was the foundation of all, and that the chemicals, the minerals balanced out was only the start -- that soil was indeed a whole complex ecosystem of its own -- microbes, invertebrates, a complex mix that wasn't going to be fixed by getting the nitrogen/phosphorous balance right.

The introductory chapter of David R. Montgomery's Dirt: The Erosion of Civilization covers those basics nicely, beginning with the touching tale of how Charles Darwin, in his last book, working with his sons, demonstrated the vital role of earthworms in soil formation and the maintenance of soil fertility, concluding that "all the vegetable mould over the whole country has passed many times through, and will again pass many times through, the intestinal canal of worms." He calculated, more or less correctly, that English and Scots worms moved half a billion tons of soil a year.

From that foundation, Dirt moves on to exploring the place of soil in early human civilization. It includes the latest research in archeology and genetics -- in its account of the origins of agriculture, which Montgomery places at the headwaters of the Euphrates from about 10,000 BC, best explored around the settlement Abu Hureyra. For the 3,000 years prior, it had been an Edenic environment of oak forests interspersed with stands of wild grain, but during a sudden dry period, the communities of hunter-gatherers who had become settled there chose to domesticate wild varieties of rye and wheat. When the rains returned approximately 1,000 years later, barley and peas, and other crops were added to the mix, allowing the village population to reach 5,000, the largest concentration of humans yet known.

This was the foundation of the great flourishing of Mesopotamia, but it faced two great problems: salinization from irrigation and silting up of irrigation channels as the growing population moved into easily eroded upland areas in search of farming land – a problem that has beset China for the past two thousand years. Such erosion was also a problem in the Bronze Age and classical Greece. Montgomery quotes Plato describing the region around Athens: "The rich, soft soil has all run away leaving the land nothing but skin and bone."

If the detail is fascinating, it is by and large familiar territory popularized by Jared Diamond. It is when Montgomery moves into the modern era that he reaches new, and frightening, territory.

The effects of inappropriate farming and drought of the American dustbowl era are well known, but Montgomery goes back, and forward, from there. He looks at how tobacco farming, based on slave labour, locked its proponents into a cycle of declining soils where the clean-till method of cultivation exacerbated erosion.

And then he looks forward to the post World War II mechanization of agriculture that resulted in the same kind of careless, mass production agriculture that ploughed across the landscape with no regard to its local characteristics. In the Palouse region of eastern Washington, a 1950 survey found that all of the original topsoil was missing from 10 per cent of farmland, and between 25 and 75% of the soil was missing from an additional 80% -- that a mere 10% was in something like its original state. Since slope is a major factor, less than 50% of US croplands have a slope of 2%, and therefore are at relatively low risk of erosion. "The steepest 33% of US cropland is projected to fall out of production over the next century."

And that's a worry for more than the US. Before World War II, Western Europe was the only grain-importing region. Latin America produced nearly double the quantity of North America in the 1930s, the Soviet Union was also a major exporter, Africa was self-sufficient. Now, the only major grain exporters are North America, Australia, and New Zealand. It is worth quoting the summary of the current state of play:

Worldwide, over two billion acres of virgin land have been plowed and brought into agricultural use since 1860. Until the last decades of the twentieth century, clearing new land compensated for loss of agricultural land. In the 1980s the total amount of land under cultivation began declining for the first time since farming reached the land between the Tigris and the Euphrates. In the developed world, the rate at which new (and generally marginal) land was brought under cultivation fell below the rate at which land was being exhausted. Although we use a little more than a tenth of the Earth's land surface to grow crops, and another quarter of the world's surface for grazing, there is little unused land suitable for either. About the only places left that could be used for agriculture are the tropical forests where thin, highly erodible soils could only briefly support farming . . . Across the planet, moderate to extreme soil erosion has degraded 1.2 billion hectares of agricultural land since 1945- - an area the size of China and India combined . . . The United Nations estimates that 38% of global cropland has seriously degraded since the Second World War . . . average cropland erosion of 10 to a hundred tons per hectare per year removes soil about 10 to a hundred times faster than it forms.

And then there's the threat of global warming. The west of the American Midwest breadbasket has already been reduced to marginal copping, while predicted vigour in the hydrological cycle is going to increase soil erosion from rainfall.

These are frightening figures (scenarios), and figures on which there has been little or no serious focus. Given the urgency of our declining soil, Montgomery might have spent less time on the historical and more on what is happening on our watch. Meanwhile, the challenge to provide food for a growing population coupled with the expectation that science can perform miracles are reasons to concern us all.