How grasslands can save the planet: Graham Harvey article

September 2, 2009 § Leave a comment

I came across an interesting article in this quarter’s Living Earth magazine.  Living Earth is the magazine of The Soil Association’s of which, I should declare at the outset, I am a fully paid up member.  I am also a fairly regular listener of the Archers, the long running story of farming folk on Radio 4.  So the name Graham Harvey caught my eye as he has been Agricultural Story Editor to the programme for a number of years now, as countless post-broadcast trails have taught me.

The article, titled Fields of Carbon, is a summary of the arguments Harvey puts forward in his recently published book, “The Carbon Fields: how our countryside can save Britain”.

The steps in Harvey’s intriguing argument go like this:

  • The world’s soils are the largest terrestrial reserves of carbon.
  • A fair proportion of damaging greenhouse gases come from soil carbon released by modern industrial farming practices – ie the move to rearing animals on grain rather than pasture.
  • We can, without too much difficulty, reverse this trend by returning animals to grazing which will put excess carbon back into the soil

It’s a seductive argument isn’t it as it means that, providing it is sustainably reared using traditional farming methods, it’s OK to eat meat after all.  So, how is the trick achieved?

Harvey goes on to explain that the world’s food supply is based on annual plants, in fact the top 3 food crops of wheat, rice and maize account for a massive 50% of land under cultivation.  Annual plants require massive amounts of oil energy to produce a crop both in terms of cultivation machinery and in terms of chemical fertilisers.  So it makes no sense to feed expensive (in every sense) grains to animals. Harvey goes on to contend that perennial plants, such as are found in species-rich grasslands could, if carefully managed, produce most of our animal feed with far fewer chemical inputs.

Harvey goes on to add a second strand to his argument, explaining that the soil is, in terms of the organic matter it contains, a massive carbon sink.  We already think of forests as an important means of trapping carbon, but in fact 82% of carbon in the “terrestrial biosphere” (now there’s a phrase to drop in conversation) is not in forests at all but is in the soil.

As you might expect, intensive cultivation tends to deplete organic matter in the soil releasing carbon into the atmosphere, whereas happily, under grass, soils rebuild their stocks of organic matter.  We are not talking small numbers here: Harvey quotes the staggering statistic that, according to a Royal Society estimate, carbon capture by the world’s farmlands given better management could total as much as 10 billion tonnes of carbon dioxide a year which is more than the annual accumulation of carbon dioxide in the atmosphere.

Harvey concludes his article with the tantalising idea that a different form of agriculture with more emphasis on grassland production wouldn’t merely help with the problem of global warming but could solve it.

It is good to read an optimistic article on solving the world’s problems for once.  Is it too simple to be a realistic solution and do his numbers stack up?  I don’t know but I’d like to find out more.  The good news is that eating organic meat (organic standards require cattle to have at least 60% of their daily feed as forage) is a sustainable choice which tastes good as well.

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