If this statement doesn’t hit you square between the eyes, nothing will: the world will run out of topsoil in 60 years. When I first heard scientist John Crawford make the claim on the ABC’s 7.30 Report a couple of weeks ago I was, literally, slack jawed. Sixty years! The implications of a number like this are massive, but when combined with a number like nine billion, the projected population of the earth in 2050, the figures are almost too much to comprehend.
Crawford, a professor at the University of Sydney’s Institute of Sustainable Solutions calls the soil depletion process “Peak Soil”. He points to China, where natural forces and industrial agriculture combine to deplete topsoil at a rate 57 times faster than it can be replenished. In the US, the National Academy of Sciences estimates the depletion rate to be 10 times. In NSW, the rate is about five times. To put the depletion in other terms, more than 75 billion tonnes of topsoil is lost annually and 80% of the world’s farming land is moderately or severely eroded.
Our topsoil bank, says Professor Crawford, will soon be empty. In Australia the problem is exacerbated because our rocks, which break down to provide the minerals in soil, are geologically ancient. Much of their weathering has already taken place. This means that our soils have generally lost much of their “goodness”, and most of the nutrients are stored in Australia’s existing plants. Read between the lines and you’ll realise that in Australia, an estimate of sixty years until the topsoil is depleted is likely to be very generous.
For those of you reading this article from the comfort of your lounge room, this might all seem a bit trivial, alarmist even. You rock up to your local supermarket week in and out to purchase a trolley full of food. Other than when banana prices skyrocket, it’s no big deal. The groceries get stacked in the pantry, eaten by the end of the week, and a fresh trip to the shops conducted 52 weeks of the year to replenish supplies.
What we’ve forgotten is Wendell Berry’s reminder that “eating is an agricultural act”. Those groceries lining the cupboard and the fruit bowl were grown by a farmer, on a farm, probably in soil. If you think soil depletion doesn’t affect you, it’s time to wake up. No topsoil by 2060 means widespread, aching hunger, the kind that compels people to fill their bellies with anything – even the dirt that once produced crops.
The good news, says Professor Crawford and other soil scientists, is that there are simple solutions to the problem. These solutions can be applied equally on a scale that ranges from a tiny backyard to a broad acre farm, and they can be very cheap to implement.
1. Keep the soil covered. Soil that has dried out during a drought has a diminished capacity to support microbial life and it’s more prone to being blown or washed away. Spread a layer of mulch, preferably something that will gradually break down to feed the micro-organisms in the soil. The use of cover crops in the vegie patch will perform a similar role.
2. Soil can be replenished. It takes time and effort to do so, but through the continual addition of organic matter to depleted soil, fertility can be significantly increased and microbial life enhanced. An added benefit of soils rich in organic matter is the capacity to store moisture. The easiest ways to improve soil at home are by making compost and growing green manures.
3. Avoid cultivating the soil. No till gardening isn’t practical (try growing carrots in non-sandy soil that hasn’t been dug), but we can all aim to make our practices minimum till. Don’t dig for the sake of exercise, and once soil has been dug, try to implement point one (above) as soon as possible. It’s also a good idea to regularly spell beds in the food producing garden.
John Crawford says that most people encounter soil as that inconvenient stuff that sticks to the sole of your shoe and has to be scraped off before entering the house. In other words we treat it like dirt. Those days have to end, and a new era of soil conservation – where we treat it not like dirt but an essential building block of life – has to begin. Start now in your own garden, and implore your friends to do the same. Unless you all want to eat hydroponic tomatoes. But then, where would we get the water?
First published in The Chronicle 13th February 2010.
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Thanks for that article. Here is an Interview by Rodale’s Lasalle well worth a listen about the merits of organic farming, and the importance of good soil! http://www.eenews.net/tv/video_guide/796