[Arid_gardener] clay soil

[Tyler Storey]

Good morning Ann,
A very dense clay soil can seem a bit daunting in planning your landscape,
but the good news is that our desert plant varieties will thrive in it once
they get in it and get growing.  Consider yourself lucky: clay soils have
excellent water and nutrient holding capacities and are much easier in the
long run than are sand or sand/rock soils.  
Fist let me encourage you to not try replacing the soil with "custom-made"
stuff.  There are a number of reasons, including expense and
impracticability, but mostly because it won't work.  You'll never be able to
"replace" it deeper than a foot and keep in mind that even the humblest
wildflower has roots a foot deep, while shrubs and trees have roots that go
2 and 3 feet deep, respectively.  
When we replace soils, lay a layer of soil on top of existing soil, or very
heavily amend our soil, we create what's called a "soil interface," a zone
that roots and water have difficulty crossing.  If you replace your soil,
one of two things will happen: either the roots and water will not cross the
interface and you end up with shallow-rooted and vulnerable plants, or the
roots and water do cross the interface and happily grow in the native soil
-- which means it was waste of time to put the new soil there in the first
place.  
The biggest challenge with dense clay soils is opening up the surface to
initially improve the water infiltration.  Once you do that and then get
your plants growing, the plants will take care of the rest.
I would recommend you try this: water your soil slowly to a depth of about 1
foot -- slowly so the water has time to penetrate without running off.  Then
wait a couple of days until the soil has dried enough to be diggable but not
wet (never dig wet clay). Look for a crumbly texture when you put your
spading fork in it. 
Next, spread a 3-inch layer of organic mulch on the surface, preferably
quarter-inch bark chips or wood chips 1/2 inch or smaller.  You can get the
bark chips bagged at home stores, or wood chips free from SRP.  You want
something small but with some substance to it.  
Either with a spading fork if you're feeling muscular, or a tiller if you're
not, work those chips well into the first few inches of the soil.  You can
add more and work them in deeper if you want.  What those chips are going to
do is open the top layer of your soil for water infiltration.  
Next, start planting your desert-adapted plants, and be sure to plant them
without adding organic material to the backfill.  Dig your holes 2-3 times
as wide as the plant's root-ball but no deeper.  And, again, back-fill the
holes with only your the soil you took out of the hole.  
After you've planted, top-mulch your soil 3 inches deep with an organic
mulch: more of the bark or wood, or something else organic.  Don't use
gravel on this soil.  Over time, your top organic mulch will slowly break
down and help to keep your soil open.  Add a little more each year as
needed. 
Do be careful to not walk on your newly fluffy clay soil when it's wet, as
that will re-compress it.
And, lastly, water your new plants deeply, slowly, and infrequently: 1 foot
down for groundcovers and wildflowers, 2 feet down for shrubs, and 3 feet
down for trees.  
I think you'll find this will help you and your plants get the most out of
your clay soil, and with minimal effort and expense.
Tyler

tyler at tylerstorey.com
http://tylerstorey.com
602-738-2978
-----Original Message-----
From: arid_gardener-bounces at CALS.arizona.edu
[mailto:arid_gardener-bounces at CALS.arizona.edu] On Behalf Of
annkz!@gmail.com
Sent: Thursday, July 12, 2007 7:43 AM
To: arid_gardener at Ag.arizona.edu
Subject: [Arid_gardener] Question from Home-Hort WWW page

Ann K
85212
annkz!@gmail.com

What needs to be done to amend very dense clay type soil? I have a small
backyard with no plant life and would like to add suitable varieties to this
full sun environment. 


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