[NAFEX] CO2 efflux vs temperature

Doreen Howard doreenh at ticon.net
Mon Mar 24 15:31:56 EST 2003

Joe Hecksel wrote:
> So, cultivating soil might be "burning up" humus through soil
> temperature effects rather than because it is "poking the embers" and
> introducing more oxygen.
> Shade that soil!

Actually, it's mulch that soil. Not only does mulch keep the soil at an even
temperature, it supports all manner of microbes, including a plethera of
beneficial fungi that feed plants and worms, and produce selective
antibiotics that thwart diseases, including those caused by pathogenic
fungi.  I spent several months talking with soil experts around the world
recently for an article on soil building that will appear in the Aug. issue
of Mother Earth.  It was a real education.  Below is what one expert says
about CO2 and the soil.

Tilling, digging and even cultivating speed decomposition of organic matter
near the surface, releasing carbon dioxide in the process.  That bacterial
feeding frenzy adds greenhouse gases to the atmosphere.  "Even if you
cultivate only 2 to 3 inches deep, more damage is done than good," says Dr.
Raymond Weil, professor of soil science at the University of Maryland.  Worm
channels and root paths are broken, and they are places where water normally
percolates downward.  Soil clumps or aggregates are broken up, too, and
there is little air space remaining in that top layer of soil.  "Instead,
you have soil that crusts over," says Weil.  Raindrops pound soil particles
and push them close together, creating an impenetrable surface.
Doreen Howard

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