On Jul 11, 2:05 am, Billy Rose wrote:

Seeing as healthy garden soil is about 20% - 30% clay do you want to
expand on your view of colloidal clay?
--
Billyhttp://angryarab.blogspot.com/

The paper doesn't mention clay colloids nor the effect of soil on the
nutritional value of vegetables. I am sorry I don't understand what
you are getting at - what do you have in mind Billy?

David

From our previous conversation, I got the feeing that there was more you
wanted to say about your plots or fields, as if there was a uniqueness
that was instructive in them. Maybe not.


Well my place is nowhere near unique but moving here and adapting to
it was instructive for me and I thought that talking about the role of
colloids in soil chemistry might be instructive to others.

Any feel for the sand, silt, clay composition of you garden? (If that is
the right term. I never did know the magnitude of your farming/gardening
efforts.) What do you grow?


Until 4 years ago I spent 25 years on a suburban block that was in
sandstone country, in a maritime warm temperate climate, very mild.
The soil was from zero to 4ft deep where you ran into the bedrock
sandstone. The soil there was dirty sand with a few small rocks. It
was on a slope near the top of a hill and you could pour water on to
it and it would be dry within 2 days. To start with I had to add
fertiliser frequently just to support low-medium intensity growing. I
spent my time begging and buying organic matter to dig in and improve
the water and nutrient holding capacity. In this situation there was
almost zero clay, I was relying on organic colloids to bind the
nutrient ions. After 25 years it didn't look too bad. But I never had
a problem with waterlogging!

The last 4 years I have been on 50 acres on the banks of a creek that
has pretensions of being a river sometimes, the climate is much
harsher. We get hard frost in winter but not ice or snow and it gets
very hot in summer, often 95F and up to 107F. The bottom land where I
am is a sedimentary basin containing coal and other layers. The
bedrock (mudstone) at my place is 4ft to 15ft down. Then there is
smectitic clay, yellow-brown, plastic when wet and like rock when
dry. Thanks to the river there is about 4-6in of topsoil which is
nearly black clay silt. It would be something like equal parts clay,
larger particles and organic matter. It doesn't drain particlarly
well but does permit infiltration. Without this topsoil I would have
nothing of value.

Most of the land was cleared over 100 years ago and was good enough
for dairy farming. Now I agist a big slice to a neighbour who runs
beef cattle and I run horses on the "home" paddock of 12 acres. Here
I am planting trees and shrubs by the hundred (the species would only
mean something to those who know Australian natives), we have an
orchard of 50 trees (oranges, lemons, limes, cumquat, apples, pears,
quince, medlar, plums, peaches, apricots, nectarines, feijoas,
hazlenuts, mulberry, persimons) an ornamental garden and a vege garden
each about 1000 sq ft. I irrigate the gardens from the river except
in severe drought when it stops flowing (there is a dam for backup),
or in flood when you watch things going under water.

What was instructive to me about this change of location was .....
where do I start there is so much. To keep this down to a sensible
length I will just talk about the soil.

I had to adjust to create drainage, luckily the place is on a gentle
slope so the main trick was to not do things that allowed ponding.
All the fruit trees are planted on mounds. If you dig down to plant
them in a hole the hole becomes a pond when it rains, the roots rot
and the trees die. The vege garden beds are built up.

I have 10 horses on 8 acres (they are kept out of the gardens mostly)
which is a very high stocking rate but not excessive in this case
provided it rains now and then. One of the benefits of the clay sub
soil is that it slowly takes up water and then releases it again. So
if you have a couple of weeks of showers the sub soil fills up. The
result is that the pasture stays greener than many areas including
some that have higher rainfall. The gardens benefit in the same way
but more over the short term.

Starting from pasture that was pH 5.5 and compacted I sprayed the
grass and waited for it to die. I then added horse manure, chicken
litter, lime, gypsum, dolomite and some potassium sulphate and had it
plowed well. I then made raised beds. These are mulched with organic
material which gets incorporated after 6-9 months. After a year the
soil is great, contrast this with the previous place where after many
years it wasn't really very productive. It is extremely fertile, pH
6.5 and has good water holding.

Clay soil is notorious for becoming water repellent but mine takes up
water slowly and the amended topsoil takes it up quickly. In summer I
can put 3cm (over an inch) on the vege garden in 1 1/2 hours and
except for some spillage on the paths it will soak it all up.

What's in the vege garden, all year round: asparagus, rhubarb,
strawberries, kale, collards, leeks, globe artichokes, silver beet,
horse radish and many cooking herbs. Right now there are cauliflower,
broccoli, cabbage, several chinese brassicas, mizuna, lettuce,
aragula, beets, peas, snow peas, broad beans, parsnips and garlic. In
summer I have tomatos, capsicum, chillis, egg plant, beans, zuccini,
squash, marrow, pumpkin, cucumber, okra and jerusalem artichokes. I
have probably forgtten some but you get the idea. I am only limited
in what I can grow by climate.

Enough shoping lists. My point is that clay country is not a death
sentence, on the contrary I would now prefer to break down clay silt
to building up sand. This is due to the colloidal nature which holds
both water and nutrients.

David