10 December 2006

Peak Soil

By Rupert Read

On the last Tuesday night in November, I attended a Norwich City Council meeting with a difference: the evening began with a presentation on 'peak oil'. Norwich's Councillors were informed in detail about a problem which will have a huge impact on us all over the years ahead: the fact that the supply of oil is 'peaking', worldwide, and soon we will have less oil each year than we did the year before. The effects of peak oil will include less availability of oil for essentially frivolous uses such as cheap short-haul flights, and more expensive oil for more essential uses such as keeping our houses warm through the winter.

The One World Column has recently featured several articles on peak oil. The problem is becoming better known and understood, even though its impact is still less widely recognised than its 'twin': dangerous climate change (See Less oil - more climate chaos?).

My topic today is slightly different. It is a problem hardly anyone has heard of. In fact, I pretty much invented the name for it myself (although I then discovered that a few people out there on the internet had already thought of the idea). Peak soil. We may be at or already past the point where the supply of soil worldwide is at its peak or in decline.

Why? Why is the world at - or perhaps already - beyond 'peak soil'? The problem is intimately connected with the 'peak oil' problem...

Most agricultural production the world over today is highly intensive. It requires high energy inputs (e.g. oil to run tractors). Such agricultural systems are very vulnerable to the impending impact of peak oil. But the most crucial vulnerability of all is this: much of our soil, in such intensive farming systems, is oil. Because intensive farming uses lots of fertiliser. And many of the most widely-used fertilisers are made from oil.

If we are dependent upon oil for our fertilisers, which are maintaining the productivity of soils in ways and to levels which are not feasible using sustainable low-intensity agricultural systems, then what are we going to do once oil starts running out? The soil will start running out too... In other words: once oil supply has peaked, then our food supply will become vulnerable, too. Because our soil will suddenly start lacking an ingredient that our farmers have come to rely on.

The way out of this conundrum is to switch now to low-intensity, sustainable, organic farming methods. There is very little time to spare, given that 'peak oil' may be with us within a few years at most.

In fact, we should make this switch anyway, regardless of the coming of peak oil. Because peak soil may already have beaten peak oil to it. Soil from the world's croplands is being swept and washed away 10 - 40 times faster than it is being replenished. Astonishingly, an agricultural area the size of Scotland is destroyed every year. Soil is deposited at a rate of 1cm per 1000 years - and is currently destroyed by careless farming methods at a rate of 1cm each 10 years!

This vital resource - our soil - is something we need to husband more carefully than ever, at this time of ecological crisis. For, after all, soils are a key factor in regulating the Earth's carbon cycle. The amount of carbon stored in soils dwarfs that in vegetation. Increased 'fluxes' of carbon to the atmosphere, such as occur when wetlands are drained, contribute to the buildup of key greenhouse gases, namely carbon dioxide and methane, in the atmosphere.

We cannot afford to allow 'peak soil' to threaten our food supplies, and that most vital of all renewable resources: the soil itself. We need to be protecting our soil, and treating it the natural way rather than being reliant on feeding it with the undependable 'drug' of oil. So that our food supply can remain reliable even when 'peak oil' kicks in. And we need to avoid our soil declining and releasing its stored carbon. So that we don't add further to dangerous climate change, by willfully letting our soil degrade and release its stored carbon into our atmosphere.

The challenge of gradually building up our soil in a sustainable way will be a key challenge of the 21st century. The good news is that, although crop yields fall when one removes the drip feed of high-input oil-based fertilisers, the soil 'recovers', and yields rise again, after a few years of carefully - managed organically - based food production. So let's get started: on turning organic food from a niche market to the mainstream.