"Oz" wrote in message
...
Gordon Couger writes

That report gives me an idea or the scale of irrigating in the UK.
200,000
hectares or 772 square mile or a block 28 miles on a side. The size of
small
county in Oklahoma. We have 2 people that work part time on irrigation
for
230,500 hectares

Oz faints

http://www.nass.usda.gov/census/cens...-36/ok1_41.pdf
about the same amount of irrigated land as the UK on it's biggest year
but
we have a lot less rain fall and lot higher temperatures.

Remember that even where irrigation is available there are years when
it's never used. Equally in a really dry summer (which were common in
the 90's) they may apply 4" or even 6" to susceptible crops.

I probably ought to add that many root crop farms are on sand. That is
almost entirely true of commercial carrot growers and very many potato
growers.
==================
A great deal of Oklahoma's irrigation it on sand for peanuts and one or two
potato farmers. Also the whole Red River Valley is a 30 to 50 mile wide bed
of worn out water and wind born sand.
http://www.couger.com/microscope/carl/sand.jpg
http://www.couger.com/microscope/carl/sand35xpol.jpg
http://www.couger.com/microscope/carl/sand35zplain.jpg
That fills the basin and the river runs under it. There are just verying
sizes of it with varing amouts of organic matter and some silt and a very
little clay now and thin. There is water on a red bed at 0 to 80 feet the 0
to 30 feet from the surface in formations that will give up from 2 to 800
gallons a minute. The quality varies from salty enough to kill on contact to
good enough for contionus furrow irrigation. There is no subsoil it is just
diffet grades of this stuff.

There are also a couple of aolial areas in the mid southwester part of the
state where they grow penuts. I am not familure with the subsoil structure
there.


The reason for this comes in the harvesting, which typically happens in
october when winter rainfall is high. A free draining sand allows east
harvesting even in high rainfall years when on a clay harvesting may be
impossible. A couple of years ago 30% of the UK potato crop was
unharvested and much of what was harvested resulted in severe field soil
damage.

Also important are quality constraints of straight roots (that haven't
bent round stones) and low cleaning costs (stones in spuds and damage).

Come to that even leeks and winter brassicae are increasingly falling
into the same pattern, with very large farmers preferentially buying
irrigated sandland in order to produce to contract for supermarkets.

The rest of us rely on rainfall. Getting an irrigation permit is
impossible and even a winter storage scheme not guaranteed to be
allowed. Since there is sod all you can do about rainfall, no water work
is ever done on rainfed crops.
==================\

Our laws that every thing below the ground goes wiht the place make a would
of difference. Most places we don't need a permit we just have to obey well
spacings for the aquifer.

There are probably going to be some changes in fossil water some day. Water
rights in the west are getting to be a very big deal. California is using
more water and power than it produces and won't produce the oil and gas in
its own state and off shore. Some day the rest of us are going to get really
****ed about it.

In the case of Red river and the land in West Texas and excess is just
circulating the aquifer. We are not using fossil water. We could in west
Texas but there is only 30 feet of it and the pumping costs for the farmer
are a lot higher and it dropping at a foot a year. It's not a linear
relationship a well into it would probably last 40 years or so but the 150
foot wells are local recharge and aren't dropping, cheaper to pump and
cheaper to repair. The did cost more to drill in the first place becase it
took 6 wells

Gordon