Re: CULT: clay... never the end

Actually, from what I know, it disappears faster in sandy soil.  Since
decomposition of organic matter is mostly a bacterial thing, it goes
faster when warm and wet than cold and dry, and those two factors
(moisture & temperature) have a much bigger effect than soil texture.
However, an equivalent amount of sand has much less surface area and
binding sites to make the aggregates with organic matter &
bacterial/fungal 'goo'.

Some researchers report positive correlations between amount of clay in
soil and amount of organic matter in aggregates.  But a lot of other
factors are involved, especially cations (especially calcium)

<Does it disappear faster in clay than in sandy soil?>

What makes soil friable is the aggregates of decomposed organic matter
(humus) with mineral soil.  Those aggregates provide some physical as
well as chemical protection from further decomposition of organic
matter.  It will continue to 'cook off', but at a much slower rate than
fresh organic matter.  Although decomposition of organic matter
continues, soil scientists talk about some components having a half life
of thousands of years (very stable!).  So although most fresh organic
matter goes away in a hurry, tiny amounts stay a long time.  It's an
equilibrium thing - soil organic matter is constantly decreasing unless
something is replacing it - plant roots, cow poop, leaves, etc.

<I suppose if one had good friable loam you wouldn't be able to tell.  >

That is interesting - I have no idea what's going on there, unless maybe
solarizing preferentially shifted that patch of dirt to fungal
decomposers instead of bacterial ones.  Right before I retired 2 years
ago, I read some research that indicates fungal decomposers (more
abundant under mulch) tie up more organic matter in aggregates than
bacterial ones do.  But that's just a wild guess & doesn't seem
plausible.  Were the two beds treated identically otherwise - same
moisture, temperature, amount and type of organic matter, cultivation,
shade, sun, tillage depth, plants, texture, surface mulch (rocks, weeds,
clods, plants, or intentional mulch)?

<The soil did stay more loose after adding copious amounts of organic
material
                   and then cooking it under plastic for a couple of
months in the heat of
                   summer.  In fact, now four seasons down the way the
solarized patch is still
                   easier to handle than a sister bed of the same clay
with the same organic
                   material.  Does the heat cause it to bind together
differently?                   Donald Eaves Texas Zone 7b, USA>

--
Linda Mann east Tennessee USA zone 7/8
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