Regenerative Agriculture

Regenerative soil practice

I’m very heartened by what I’m picking up on the web regarding activity related to regeneration of soil.  This might seem to the uninitiated as a very ho-hum subject, but it’s not.  Regeneration of soils that have been degraded over time by agricultural practices and restoration of prairies that have lain fallow and unproductive of plant growth, has the capacity to sequester huge quantities of carbon dioxide from the atmosphere.  The soil C pool (I’ll use C to indicate carbon sequestered in the soil, directly equivalent to atmospheric CO₂) is estimated to be about 3.3 times the CO₂ in the atmosphere.  In pre-agricultural times the organic carbon sequestered in soil was much greater than it is today.  It’s estimated that conversion of natural to agricultural ecosystems has caused depletion of the stored carbon in soils by as much as 60% in the temperate regions and 75% in cultivated tropical soils.  Worldwide, these losses have translated into a substantial enrichment of atmospheric CO₂.  One way to reverse this process would be to transfer CO₂ into long-lived pools of organic plant matter, by judicious use of arable land and environmentally sound maintenance of plant ecosystems generally.  In other words, we need to return soil to something like its pre-human conditions.  How can this be done?  A great place to start learning about this subject is an article entitled “Can Dirt Save the Earth?” in a recent issue of the Sunday New York Times.  In general, the restoration of the soil carbon pool includes woodland regeneration, no-till farming (see the figure at top), use of cover crops, nutrient management, agroforestry practices, and growing energy crops on spare lands. The largest potential for applying regenerative soil methods is in conventional agriculture.  Ben Dobson has a nice YouTube presentation on how this works. 

Regenerative agriculture practices can be scaled up, but it will mean changing the mindsets of big agricultural interests.  In  the book Drawdown, which I’ve mentioned in an earlier blog, regenerative agriculture is 11^th out of the 100 individual initiatives in terms of the total amount of CO₂ each can remove or potentially avoid.  The economics estimates by the Drawdown team, thoroughly reviewed by a large and distinguished Advisory Board, are impressive.  It would cost on the order of $57 billion net to convert 1 billion acres of land to regenerative agriculture by 2050.  That’s relatively little to spend over 30+ years period.  On the other hand, the savings would be on the order of $ 1.9 Trillion!  There is space here for me only to suggest where those savings come from—less water, reduced use of insecticides, pesticides and synthetic fertilizers, less utilization of heavy machinery; the list goes on.

In the transition to agricultural societies about 10,000 years ago, human dependence on soils became more direct.  Cultivation of virgin soils exposed them to loss of topsoil during seasonal rains The loess plateau of north China, for example, began to erode more quickly under human management, earning the Yellow River its name. We humans have had a long history of despoiling land, breaking the sods of steppes and prairies.   We have come to the point where we must retrace our steps, and not just because of rising CO₂ levels.  We are once again coming to a hard won realization that nature is a deeply connected web of existence.  Grossly disturb one part of an important ecosystem, and see the effects ripple outward.  Planet Earth is becoming increasingly crowded.  Land available for producing food will become increasingly dear. It never was a good idea to allow topsoil to blow away in dust storms or wash down streams and rivers into the oceans, losses caused largely by repeated tilling.  We will have to work our way back to something resembling the natural state of the land, with the complexity of life forms able to sequester CO₂, produce needed nitrogen, and sustain a vigorous agriculture.