Re: CULT: soil organic matter - long & technical

Betty, to build up organic matter, one of the things that has to happen
is for the organic matter to become 'glued' together with mineral soil
particles (clay, silt, or sand sized particles) into large soil
particles (organic matter aggregates).  This 'glue' comes from worm guts
(no, don't squish the worms, let them eat dirt), bacteria, and fungi.
These aggregates are what gives soil the wonderfully crumbly feel that
as gardeners we know and love.

Organic matter in its 'raw' form (i.e., dead leaves/hay) is mostly
simple chemical forms like sugars, polysaccharides, etc that are very
easy for worms, bacteri, and fungi to 'digest'.  Because they are so
'tasty', these forms of organic matter don't last long in soil.  They
can be very important in forming soil aggregates in the short term, but
as we all know from experience using these things as mulch, they are
very much here today, gone tomorrow.  Turnover time (the time it takes
to be completely chewed up) for these materials is usually less than a
year (depending on a lot of things - warm & moist goes faster, cold &
really wet goes slower).  After that, it is gone.

Raw organic matter also contains relatively small amounts of compounds
that are harder for worms, bacteria, and fungi to digest.  This includes
things like lignin, aromatic hydrocarbons, & other ring structures
(remember organic chemistry?).  For long-term accumulation of this
resistant or recalcitrant organic matter, you have to add a lot of 'easy
to digest' material every year to get just a little of the long-term
stuff.  If you add material that has already been composted, some of the
really fast turnover material will already be gone, leaving more of the
slow turnover organic matter.

Bottom line - add LOTS of compost, less fresh material; add earthworms
if they aren't there already; add nitrogen to help the bacteria stick
stuff together.

Clay is another topic - I will post something about it later.  The
technique Bill B posted for determining sand, silt, clay and floating
organic matter fractions is more or less the standard lab technique for
particle size determination.  Add a surfactant (non-sudsing soap or
water softener) to help disperse aggregates.

I didn't look up your original post, so apologies if this is off course
from what you wanted.

Add worms & feed them.
--
Linda Mann east Tennessee USA zone 7/8
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