Finally, a bid to save our soil

Hilary Benn's recognition that we need to look after our soil is long overdue – a fixation with chemistry threatens our civilisation
Graham Harvey
guardian.co.uk, Tuesday 29 September 2009 10.30 BST
It's good to know the government has realised we need to take rather better care of our soil if we're to stand a chance of surviving on this planet.
Announcing a new soil protection strategy, the rural affairs secretary, Hilary Benn, declared: "Good quality soils are essential for a thriving farming industry, a sustainable food supply and a healthy environment."
Quite so, Mr Benn. But what took you so long? For an old farming hack like me it has been obvious for years that the way we've been treating our soils is bad for our health as well as for our environment.
In a nutshell, the constant pounding we've given our farmland, both with chemicals and with giant machines, has seriously compromised its ability to go on feeding us. If we go on treating it in such a cavalier way our civilisation is likely to go the way of all the others who wrecked their soils – starting with Mesopotamia.
The roots of our own particular form of soil abuse lie in the ideas of an influential 19th century chemist called Justus von Liebig. He propounded the theory that soil fertility was principally a matter of chemistry. You simply totted up the amounts of plant nutrients taken off in a crop and replaced them in the form of fertiliser.
In this way the land could be induced to go on producing crops indefinitely, Von Liebig reasoned. It's this 19th century paradigm that has underpinned our food system ever since. Around the world farmers have thrown a few major chemical elements onto their fields – principally nitrogen, phosphate and potash. And that's about it.
The idea that you might also need to apply some organic fertiliser such as animal manure has disappeared on many lowland farms.
Judged solely on the basis of crop yields the system would appear to have worked reasonably well. But serious drawbacks have begun to appear with real implications for human health. Many everyday foods are now depleted in health-protecting nutrients. And the soil itself – the only guarantor that we can go on feeding ourselves in the future – is losing its structure and eroding away.
Prof Bob Watson, chief scientific adviser at the Department for Environment, Food and Rural Affairs (Defra), sounded the alarm bells last year when he reported on a World Bank-funded investigation into global farming technology. He said: "We are putting food that appears cheap on our tables; but it is food that is not always healthy and that costs us dearly in terms of water, soil and the biological diversity on which all our futures depend."
The fatal flaw in our food system is that it is fixated on chemistry while taking little account of the life forms in soil which are the true builders of fertility. Von Liebig became known as the founder of agricultural chemistry. Unfortunately there was no one around to make the case for agricultural biology, which, if anything, was more important.
Commerce has been happy to perpetuate this myopic view of soil fertility. A handful of large corporations have made handsome returns from peddling chemical fertilisers to farmers. Why would they be worried about soils becoming damaged and breaking down?
One of the consequences of soil damage is that crops are unable to take up the nutrients they need. As a result they become unhealthy and vulnerable to attack by pests and diseases. This hands another revenue stream to the chemical companies, who are then able to cash in with the sale of pesticides.
It appears from Benn's pronouncement that the proverbial penny has finally dropped. Farmers are being encouraged to abandon damaging techniques such as ploughing and substitute techniques like "minimal tillage", a less brutal and invasive way of preparing soil to receive a new crop.
The aim of the strategy is to increase the level of soil "organic matter", an all-encompassing term for life below ground. It includes living organisms from microbes to earthworms, by way of nematodes and fungi. It also includes the dead and decaying remnants of animals and plants. It's these myriad life forms, together with the materials they work on, that supply nutrients for crop plants, for grazing animals and ultimately for us human beings.
Thankfully the government has recognised that soil fertility is not simply – or even principally – a matter of chemistry. The challenge for farmers is to create the conditions that allow life below ground to flourish. When soils are genuinely healthy and fertile, the future of our food supply – and its quality – is assured. So is the future of the planet.
Fertile soils represent a far greater store of carbon than damaged ones. Even as farmers begin to rebuild levels of organic matter in their soils, they'll be removing carbon dioxide from the air and locking it up safely below ground.
Soil represents the largest terrestrial carbon sink. It contains three times more than all the world's vegetation. That's why Benn's new protection strategy is good news for all of us. Unless, of course, you happen to have shares in the farm chemical industry.