Total Pageviews

Friday, November 10, 2017

Dirt

This is a book review of David R Montgomery's book Dirt which he wrote before Growing a Revolution.  In Growing a Revolution he describes how a few farmers scattered far and wide across the planet have worked out a better way of farming which restores the soil with all the benefits this brings.  In this book Dirt, he describes how civilization after civilization,with very rare exceptions, have destroyed themselves by trashing their soils.

Clearly there are other factors involved in the demise of civilizations but at the core, if you can't feed your population, you are on a slipery slide.

A common sequence Prof Montgomery describes is a move into a new valley and a build-up of farming.  With a reliable source of food, human populations  increase at a truly astounding rate.  In the words of one of my favorite authors, Richard Dawkins,  "If ever there is an increase in food production, population will rise until the previous state of misery is re-established." It is not inevitable but very very common. 

In a few countries the population increase and with it the destruction of ever more sensitive soils has been reversed and would you believe it, we are fighting it tooth and nail. (see above link).


As the bottom land is completely occupied, the new generation of farmers move up slope and farm ever steeper land.  When the plow is used, the die is cast.  Plowing moves soil down hill and the removal of ground cover greatly accelerates natural erosion by rain and wind which, moves the soil even faster down hill.  Soils either accumulate on the valley bottoms and/or are washed into the stream or river to be exported to the sea.

  For instance, early in American (European) farming, they plowed straight up and down the slopes, would you believe???  Contour plowing was a "great innovation" and even this "innovation" only slowed down the destruction.

 The Americans eventually reached the great central Loes plains, leaving destruction behind them and proceeded to destroy these soils as well.

On a visit to Virginia I saw many stone gates leading into a young forest with no drive way visible.  When I asked the locals about this curious occurrence, they told me that these were abandoned tobacco and cotton farms.  The farmers had moved west when the soil ran out.  In fact, it was common for a farm to last only for a decade or two when the farmer had to move west.  This, more than anything might explain the constant western movement of the Americans into lands owned by the first people.

On a recent visit to Otterton, in Devon to see the return of the beavers we were told that Otterton was once a sea port.  Soil erosion had filled the estuary and Otterton is now land locked.  We found out later that this is a very common situation around the UK.

Just last month, we took a trip to Bulls in North Island (New Zealand)  There we saw plowed fields all over the place and the streams ran brown with silt.  Our streams here in Canterbury are the same when there is anything above a very gentle rain.

the present zeitgeist is climate change and we are finally waking up to its dangers.  The more serious crisis may just possibly be the destruction of our soils. This is exacerbated by our short term rush to the maximum short term profit rather than a greater long term profit.

No comments: