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Stubble soil moisture

Every year I put together a map of Prairie soil moisture for Grainews readers.

This year’s map is simply a compilation of the three provincial maps — using standard criteria for all three. Refer to the provincial websites for the individual province maps.

In its original farm, the categories for the Manitoba moisture map start (less than four inches of available water) where the Saskatchewan map ends (more than four inches available water). That reflects the reality of the rainfall differences between the two.

Let me thank Ken Panchuk and his crew in Saskatchewan. The Saskatchewan Agriculture Ministry maintains a large cadre of rainfall recorders — many who do actual soil probing to determine the wetting front as of freezeup.

In Manitoba, Marla Riekman has taken over from Andy Nadler. They actually take soil samples at about 109 sites, 75 of which are after an annual crop.

Alberta data comes from the Alberta Agriculture and Rural Development website. The map is based on a computer model.

Special thanks to David Waldner of Agriculture and Agri-Food Canada (AAFC) for providing me with a map of Western Canada with precipitation from August 18 to October 31, 2011. David also acknowledges other federal and provincial agencies for the part they play in the group that makes it all happen.

This 2011 map is remarkably similar to 2009, 2008 and 2007. Anything east of a line drawn from North Battleford to Moose Jaw, Saskatchewan is in good shape. Most farmers in Alberta and western Saskatchewan will be watching the sky with anticipation as soon as the crop is seeded. Once again, these farmers will have to rely on timely rains during the big water use period of about June 10 to July 20.

Last year, for the fall 2010 map I set up a “Super Wet” category for parts of eastern Saskatchewan and eastern Manitoba. Parts of the Weyburn, Melville and Meadow Lake area of Saskatchewan may have shades of that this year also, based on a total summer/fall rain of 20 inches or more, and the fact that many fields never got planted so there was no crop to use up any water.

Crop Yields

The table below the map shows some 2012 yield possibilities based on soil moisture and spring rain. This will give you some numbers to play around with when calculating ‘what ifs’ for 2012. I warn you that the canola yields from my equations are on the low side for the yield potential of modern herbicide tolerant hybrid varieties. In fact, in light of recent years yields most of the yields in the table seem on the low side. We will get the other side of the average.

And, before we take all the credit for the higher yields we see today, we must remember that higher atmospheric carbon dioxide is a good thing for crop yields. A recent issue of “Better Crops with Plant Food” (from the International Plant Nutrition Institute, available online at showed a seven to 16 bushels per acre yield increase with 550 ppm carbon dioxide as compared to 385 ppm. †



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