With the temperatures soaring into the mid-to-high 30s across the prairies and staying there, crops are starting to feel the effect. To make matters worse, most farmers across the prairies had a soil moisture deficit to start the growing season off.


This is why Dr. Ross McKenzie, a retired Agronomy Research Scientist with Alberta Agriculture, is calling this a worse-case scenario.


He says there are arid conditions in southern Saskatchewan and Alberta and that the central and northern parts of those provinces and Manitoba are not much better off.


Lack of Soil Moisture Compounds Situation


He says most years, producers would see more precipitation during the winter – early spring and during the growing season to help the crop along.


McKenzie adds while there was some rain during planting, farmers were sitting on relatively dry subsoil conditions for the most part due to an unseasonably warm winter and less snow than in previous years.


“As a result, there was less contribution of snowmelt toward soil moisture in the spring in southern areas like in the brown and dark brown soil zones,”

McKenzie said.


April, May, and June had below average to well below average precipitation, meaning there was no making up the moisture deficit.


The amount of stored soil moisture in the ground has been lower than normal in most places across the prairies.


He says many dryland crops, particularly across the southern prairies in the brown and dark brown soil zones, are struggling.


Prolonged Exposure


During a typical year you may see around five days above 30 degrees during the growing season in the central prairie region . This year, many farmers are staring down the barrel of 10 straight days of scorching hot temperatures.


McKenzie says this will cause your crops to wilt a lot more than usual during the day, as they work to try and keep themselves cool by taking up moisture from the soil. However, the plant’s ability to do this has been severely compromised with the current conditions. When there is good stored soil moisture, the leaves will be able to transpire; however, that is severely compromised with the current conditions.


Wilting is a sure sign that the plant can’t being able to keep up with water intake requirements.


When a crop goes into a moisture deficit condition during the vegetative growth stage, you will see leaves and stems growth rates reduced to severely stunted.


The saving grace is usually in the evenings when the air temperatures cool then the plants cool down and will recover from wilting. However, it will only help the plant for so long during a heat wave like the one we are experiencing this summer.


McKenzie points to the example of a former agronomist student who sent him pictures of a completely wilted canola crop taken during the heat of the afternoon and compared them to photos taken the next morning that showed the crop had completely recovered.


McKenzie says that means that the crop can’t keep up with moisture uptake during the day.


“The soil moisture conditions are obviously deteriorating, and so how long can they really go with this heat before they literally run out of water?”


McKenzie says we are now seeing permanent wilting scenarios play out where the crop doesn’t recover overnight across some areas of Southern Alberta and Saskatchewan. If there is not moisture soon, the crops senesce and die.


He says at this point, farmers across the prairies are probably looking at reduced yields in many places, with total crop loss in some areas if there is no significant precipitation very soon.


At this point, crops such as wheat, barley, and canola are getting into advanced stages and require between 7 and 10 millimetres of water a day because of the extensive heat. In a lot of southern areas, there just isn’t that kind of water stored in soil.


According to a report on Crop Water Use and Requirement from Alberta Ag, the signs a cereal and oilseed crops is struggling with getting enough water include:


• Older leaves, wilt, die and eventually fall off

• Tillers are aborted in cereals

• Stem elongation being reduced

• Reduced branching with canola


All these symptoms ultimately mean there will be reduced yield and it the worst case possibly total crop loss.


McKenzie says with the prospect of facing significantly reduced yield, you have to carefully evaluate if it is worth the cost to apply additional in-crop fertilizer, insecticide or fungicides, knowing your revenue might be significantly reduced.