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Jun 23, 2010 by Lee Hart

Dealing with too much moisture

Even while waiting for fields to dry out, farmers are
reluctant to complain about too much moisture. Particularly producers in
southern Alberta and Saskatchewan say too much moisture isn’t great, but there
have been many years when they face the hardship of too little moisture.

At an indoor “crop walk” in Lethbridge this week about 100
producers shared some thoughts on managing crop land that has received anywhere
from eight to 12 inches of precipitation so far this spring. It was supposed to
be a field crop walk, organized by Alberta Agriculture and the Southern Applied
Research Association to look at research plots demonstrating a number of crop
production treatments. But, Ross McKenzie, agronomy research scientist with
Alberta Ag in Letbridge said the plots were just too wet. He had been out with
pumps to get standing water off the fields, which are near Ag Canada’s
Lethbridge Research Centre, and it looked like the plants would make it, but
having an on-site look would have been a gum-boot only affair.

There was a lot of discussion about crops and moisture and
here are a few of the highlights.

·   The
southern prairies are considered dry, but 2010 was the fourth year in the last
16 to be considered as ‘wet’ years. They included 1995, 2002, 2005 and now
2010. Lethbridge had about eight inches of moisture in four major weather
events this spring, further south at Cardston it was closer to 13 inches, and
east towards Bow Island it was about 11 inches.

·   Along
with the moisture, average temperatures have been cool, which has delayed the
crops anywhere from two to four weeks. Just for interest, at 20 C degree
temperatures it takes barley about five days to germinate, at 10 C it takes
about 14 days and at five C it takes 25 or more days to germinate.

·   If
plants have been under standing water for five days or more, they are probably
finished.

·   While
yellowing crops under too much moisture is fairly normal, the yellowing could
be caused by a combination of factors – cool temperatures, lack of oxygen, and
with saturated soils crops don’t have the same nutrient uptake which leads to a
lack of nitrogen.

·   If,
as moisture recedes, crops don’t look like they are bouncing back from the
yellowing, top dressing with nitrogen fertilizer may be an option. Good
products are 28-0-0 (urea) and 28-0-0 (UAN liquid) or even 21-0-0-24 (ammonium
sulphate). Granular products are good, but the downside in a year like this, is
that you still need moisture after application to carry the nitrogen into the soil,
or you risk loosing 25 to 30 percent to volatilization.

·   McKenzie
says if producers do plan to top dress, aim to apply 30 pounds of actual
nitrogen per acre, and “don’t mess around with a 10 pound rate”.

·   A
soil test and/or tissue test may not be accurate or timely enough in a year
like this to give producers a clear message on whether top dressing is
necessary. It comes down to a producer call – look at the crop, if it is a good
stand, with good potential, and the potential pencils out with market prices,
invest in the top dress application.

·   Unless
you are keen on chemfallow, if you have some unseeded fields this late in the
season, it might be best to get something seeded and growing to use moisture
and control weeds. A cereal can be seeded, if you can make use of green feed in
the fall, or perhaps consider a legume such as sweet clover, as green manure.
Sweet clover is cheaper than peas and fixes nitrogen in the soil, making it
worthwhile, even under a zero-till cropping system. Alfalfa is also a good option
on soils prone to salinity.

·   You
can also manage those unseeded acres so you can get a winter cereal such as
winter wheat seeded in good time in early September.

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Lee Hart

Lee Hart


Lee Hart is a long-time farm writer, and honorary member of the Alberta Institute of Agrologists, with many observations on the agriculture industry, who never hesitates to admit he is wrong (should that ever happen.)


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