[tomato] Drip Irrigation Systems and more.

Paul Reynolds (Tomato@GlobalGarden.com)
Thu, 15 Jul 1999 09:45:20 -0500


There are meter sources everywhere.  Irrometer, Ben Meadows, Forestry
Suppliers, Geoflow, Meta fim and many others.  I'm not going to advocate
anyone in particular.  You just have to shop around and see what one
will suit your needs the most.

For those of you folks that are interested in learning more about drip,
there is a listserver that specializes in drip systems.  These folks are
the experts and there's a mix of PhD's and the professionals and regular
Joe's such as you and I.  The name of the list is Trickle-L.  Send
"subscribe Trickle-l" to LISTSERV@crcvms.unl.edu.  The owner of the list
is at rmead@lightspeed.net.  The folks subscribed to this list ranges
from gardeners, vegetable growers, researchers, vineyards, farmers,
orchard growers etc.  You name it and their there.

As far as watering, I totally agree with Mr. Yarnell.  You need to pay
attention to the different environmental conditions.
Evapo-Transpiration is the driving force for water uptake.  The ET will
vary with different conditions.  A cool and cloudy period, the ET will
be less.  A hot period with dry winds, the ET will increase.  Basically,
the higher the ET, the more water that plant is going to require.

I don't know what the "general" ET rate for tomatos is.  This is
something that I've been intending to find out and I guess I just need
to get around and get it done.

Also, a tensiometer will work on determining your moisture needs as
well.  This is what I prefer.  For a down to earth definition, this is
the measurement of the tension or suction with which water is held
within the soils.  Tensiometers are used very successfully in
determining irrigation needs when the soil is to be kept well supplied
with water.  However, a moisture meter is probably less expensive.  Just
need to price them.

The main purpose of "deep" watering is to flush the system.  Basically,
anytime you fertilize or add something to the soil, there is always an
end result and, in a dry climate it, it is generally salts and sodium,
and in some instances boron, that need to be moved below the root zone.
This is where it's nice to know what the source water looks like.  If
it's hard or if it's salty, then you need to flush these to a point just
below the root zone more often.  Hardness and salinity will also affect
fertilization.  But, being in a garden type situation, I don't think you
would need to worry about the chemistry too much.  :-)

Also, deep watering will help your plants to root deeper.  Just as long
as you aren't keeping the surface soils "too" wet.  Plants are
oppurtunistic and will only root as far as they need to in order to
attain sufficient water and nutrients for growth.  Thus, if you only
water the top six to eight inches, this is where most of the root mass
will be established and that plant is more apt to feel harmful affects
from dry conditions.

Hope this helps and sorry about the lengthiness of this post.  :-)


Paul Reynolds
Environmental Agronomist
Austin Texas