Re: no-till gardening
riedy wrote:
>
> I think Richard Starkeson has made a very apt observation about topsoil
> being linked to rainfall ("I think the principal reason we have so
> little loamy topsoil here, is because with the light seasonal rainfall,
> there isn't enough year round moisture to allow for soil buildup through
> decomposition of the plant material on the surface, and that the growing
> season is so short, thus not producing (in the grasslands) a lot of
> annual vegetative debris. Even in our heavily forested areas, there are
> only a few inches of humus on top of the subsoil.") Living as I do in a
> desert area (desert as defined by the evapotranspiration rate) with
> heavily alkaline adobe clay soil and normally an annual precipitation of
> 8 inches (200mm), on a half-acre with 200 large deciduous trees (so you
> can imagine the fall of the leaf in autumn), I can attest that my soil has
> no topsoil or humus except where I have created it by the old spade,
> incorporate and liniment method. But I have to continually water to keep
> these areas friable and keep the earthworm population alive. Where I have
> allowed fairly dense copses to develop and remain untouched, there is
> little leaf debris build up from year to year. This is because the
> debris is bone dry for the most part and very high spring
> winds scour the area before the trees are leafed out enough to keep the
> winds from blowing the leaves away.
>
> I would be very interested in seeing the Israeli report, especially to
> see what their moisture management is.
Unfortunately, I have never seen the original report, only a summary in
Organic Gardening. I do have a proper reference to the original work
which someone sent me, but not having any access to a suitable
scientific library nowadays, I have been unable to follow it up.
I am afraid I can't lay my hands on this reference immediately, but will
try and look it up once the Christmas rush is over ( complicated by
looking after grandsons while their mother recovers from surgery).
Richard is also interested.
Just one small point. I have seen it pointed out recently that shallow
soils are the norm in forests, even with good rainfall, because so much
of the carbon the trees make is added to their structure, limiting the
bulk of material available for recycling. Conversely in grasslands where
much of the top hamper is shed yearly, deep soils can develop as this
decays - provided of course thee is sufficient moisture.
Moira
--
Tony & Moira Ryan <theryans@xtra.co.nz>
Wainuiomata, New Zealand. (on the "Ring of Fire" in the SW Pacific).
Lat. 41:16S Long. 174:58E. Climate: Mediterranean/Temperate
