Soil Temperature Approach Critical Point for Winter Wheat
The recent cold weather has growers concerned about the health of their winter wheat crop.
The critical temperature for our most winter-hardy winter wheat varieties is about minus 4 degrees F, while varieties developed in states to the south of us can be injured when temperatures dip below 14 degrees.
Although air temperatures have been below these critical values, it is the soil temperature around the crown of the winter wheat plant that is important. Soils retain a great deal of heat, so soil temperatures lag behind those of the air.
Snow cover insulates the soil and is very important for the survival of winter wheat crops during most years. With little or no snow earlier this year, soil temperatures were getting low enough in some areas to cause concern, particularly if the variety sown was not one of the most winter-hardy types.
In addition to variety, the size and health of the plant can impact how well the crop will tolerate the cold.
Generally, plants that have four or more leaves in the fall can withstand a more prolonged period of cold than smaller plants because they have more reserves in their crown. Fields that have a history of no till and have a good level of crop residue from the previous season may insulate the soil to a degree, much like snow cover.
For growers who are curious about the viability of their winter wheat crop as spring approaches, dig up several seedlings throughout the field and put them in a plastic bag with a bit of water, close the bag and leave them at room temperature. After a few days, viable plants should begin to grow.