According to Alastair Fitter, fellow of the Royal Society and University of York professor, a single teaspoon of soil can contain thousands of species and millions of organisms. Sadly, however, its significance is still largely unrecognised… Here, he explains why soil is central to our survival.
Imagine you are an animal in a zoo. What do you absolutely need your keeper to supply you with if you are to survive – not live well, just survive? Top of the list would be cleanish air with enough oxygen, cleanish water with no dangerous infectious diseases, and a supply of food. There are many other things you’d probably like – warmth, some comforts, privacy, but these are not biologically essential for your survival.
Back in the world that we still inhabit, those remain the bare necessities of life. Air is abundant; we just have to keep it clean. Water is increasingly scarce, but the overall supply for the world as a whole is not in threat, just its distribution and quality. But food? In the world we have constructed, that has to be brought to most of us. But suppose it were not so; if we each had to be self-sufficient, what would we need?
Of course, the answer to that question depends on what you eat: steak every day and you’d need a lot more land, but we’re talking about a subsistence diet here and the answer seems to be less than 1 hectare (1 ha = 100 m x 100 m) per person. In the UK, there 6 million hectares of croppable land according to DEFRA and there are over 60 million of us, so if we had to be self-sufficient without imports we would have less than a tenth of a hectare per person – that’s about 30 x 30 m of land.
The world population is 7 billion and FAO estimates that there are 1.5 billion hectares of croppable land under cultivation. That works out at 0.21 ha per person, or a plot 45 x 45 m. For comparison, a football pitch is 105 x 68 m. Presumably, since there is enough food in the world to feed those 7 billion people (it’s just not equitably distributed), that is enough for self-sufficiency.
Over the next 30 years, the UN expects the human population to grow to between 9 and 10 billion, so that would reduce our personal global plot from 45 x 45 m to 38 x 38 m, which is a much bigger reduction than it looks, nearly 30%. We could manage a small increase the area of croppable land – indeed we are doing so in the Amazon and Indonesia right now, but with disastrous environmental consequences – but even so not enough to keep pace.
Given that we are not feeding the world’s population effectively now and that there is barely enough land to do so, we might be expected to be looking after that land, but we are not. What matters on the land is the soil.
Soil is amazing stuff: it is a vibrant ecosystem, with more biodiversity that almost anywhere else on earth. A teaspoon may hold thousands of species and millions of organisms. They are mainly microbes and most of them are unknown to science, but they are performing utterly vital roles for the continuation of life on earth, decomposing organic matter and operating the cycles of nutrients that enable plants to grow and feed the rest of the living world.
Soil, however, is just dirt to most people and we discard it casually. Historically, we have probably covered 2% of the world’s most productive soils with cities, turned 5% into salt-deserts by incompetent agriculture and allowed 10% of the world’s cropland soils to be washed or blown away. And that continues. In Europe at the moment, we lose between 5 and 40 tonnes of soil from every hectare of land every year. At the upper end, that is 0.2% of the soil each year, and since it is mainly the most fertile upper layers that are lost, the damage is disproportionate. In 25 years, that loss equates to 5% of our soil.
Those trends continue: if you do the calculation on the amount of land available to feed each person in the world again, this time reducing the stock of soil by another 5%, our personal global plot for food production goes down by another 100 m2.
There’s nothing new about this. We have always been good at trashing our planet. Just look at the catastrophe that befell the American prairies, once a sustainable grassland grazed by millions of buffalo. On 22nd April 1889, Oklahoma – then Indian Territory – was opened to colonisation. There was a land grab; by the end of that day the population of Oklahoma had swelled by between 12,000 and 40,000 hopeful homesteaders (and many who were out to make a quick buck). By 1892 the population of Oklahoma was 130,000.
The late nineteenth century was a time of above average rainfall on the prairies, but even so in the first year drought destroyed the new farmers’ crops and Congress provided aid. For a while, the new farms flourished, but they were mining the fertility of the soil, built up over thousands of years. Then drought returned – unsurprisingly as this was prairie. The lack of trees was the clue.
Just 35 years after the land grab, drought returned in earnest. The farms failed. The soil blew away and dust clouds spread as far as New York and the east coast of the US, bringing darkness at noon 1500 miles away. The farmers, all heavily mortgaged, went bust and were evicted. The ‘Okies’ were forced out and their plight was recorded by John Steinbeck in his greatest work, The Grapes of Wrath:
“And then the dispossessed were drawn west- from Kansas, Oklahoma, Texas, New Mexico; from Nevada and Arkansas, families, tribes, dusted out, tractor-ed out. Car-loads, caravans, homeless and hungry; twenty thousand and fifty thousand and a hundred thousand and two hundred thousand. They streamed over the mountains, hungry and restless – restless as ants, scurrying to find work to do – to lift, to push, to pull, to pick, to cut – anything, any burden to bear, for food.”
To find out more, come along to one of our weekly meetings, held each Tuesday at Spark York from 7.30pm, (excluding the 31st Jan).