Your Reading List

Stubble soil moisture, November 1, 2015

Les Henry’s annual soil moisture map gives us a true view of water availability

(click image for larger view)

This map shows the best estimate of subsoil moisture from three inches to four feet.

First — this is a map of general conditions in general areas. Do not get too hung up on the exact placement of lines. But, it is still very useful in planning for 2016 outcomes. With a soil full of water a crop will hang on for a long time.

Second — the thank yous. A special thanks to Andy Nadler of Hydromet Solutions for the new basemap.

Thanks also to Ernie Sirski of Dauphin (brother of Andy Sirski, Grainews editor for many years and regular columnist.) The Dauphin airport site showed only 5.5 inches of rain for April 1 to October 31, which would have put it in the RED category. But Ernie assured me that the very dry area did not go far. Grandview and Roblin had 12 inches for the year. Yorkton east was also on the dry side so I mapped a small area of Dry.

I am always hesitant to use anything but GREEN or BLUE for wet Manitoba but last year I mapped Dry in the Morden Winkler area. Lo and behold, in late May John Morris of Grainews staff in Winnipeg sent me a video of soil drifting in the Winkler area.

For the last few years the map showed good to excess soil moisture for all but a big chunk of Alberta and West Central Saskatchewan. When the 2015 May rains failed almost everywhere and June rains also a bust, many were surprised by the good crop. No surprise to me. As this columnist has said many times: “Water in the soil is like money in the bank.”

As long as the seed was placed to moisture and the crop came up and did not freeze, good crops were had by many. With all the frost in May I was wishing for a bit more global warming. It was the cold weather in May that hurt many hay crops, not the drought.

With the dry weather the diseases were at bay and crop quality was mostly good. I have never seen a canola crop with such great cabbage leaves that hardly had a trace of disease. In August I suggested to my grain buyer that they should get ready for more canola than forecasters with fancy computers were predicting.

For 2016 most of Saskatchewan east of a Swift Current-Battleford line and most of Manitoba is well set to survive a dry spell in spring, if the crop comes up. Seed it to moisture. The main period of crop water use is from mid June to late July — the grand period of growth with long days and warm temperatures.

I still keep hoping that smart young folks will come along with a better map than this and I can retire my four colored pencils. It will certainly not be the SMAP program using satellite data, even if the dead satellite comes back to life. SMAP reads only the surface few centimeters. Surface moisture is here today and gone tomorrow. And if a farmer wants to know surface moisture all s/he has to do is kick the soil with the toe of their boot. It is critical to germination but not much else.

It is the subsoil moisture from three inches to four feet or more that determines the ability of a crop to survive a long dry spell.

What is needed is a map showing areas with potential high water tables that have residual moisture at depth and those areas with permanent very deep water table that never reacts with surface moisture. We will talk more about that in a future column.

About the author


Les Henry

J.L.(Les) Henry is a former professor and extension specialist at the University of Saskatchewan. He farms at Dundurn, Sask. He recently finished a second printing of “Henry’s Handbook of Soil and Water,” a book that mixes the basics and practical aspects of soil, fertilizer and farming. Les will cover the shipping and GST for “Grainews” readers. Simply send a cheque for $50 to Henry Perspectives, 143 Tucker Cres., Saskatoon, Sask., S7H 3H7, and he will dispatch a signed book.



Stories from our other publications