Ag Instructor Vic Martin: Here we go again (with drought

Great Bend Tribune
Published December 10, 2017

We will finish up the discussion of pests and weather next week.  Today, let’s take a detour to consider where the area is in terms of the 2018 wheat crop and moisture.  The Drought Index released yesterday shows that all but parts of West Central, Southwest, and Southeast Kansas are either Abnormally Dry or in Moderate Drought.  In our area, it is essentially abnormally dry above the Arkansas River and in moderate drought below it.  So today, as we head in the official start of winter in less than two weeks, what is going on and what does all this mean, if anything?

  • The Drought Index is really an indicator of soil moisture for our purposes.  It takes into account various weather data from week to week such as air temperature, precipitation, etc. and the effects of weather on conditions.  Also keep in mind that conditions that are a drought in Southeast Kansas aren’t necessarily a drought in western Kansas.  A drought index compares conditions as they are compared to where they should be for an area.
  • We are in a “La Nina” pattern.  This column has discussed this before.  Ocean conditions from Peru westward towards Indonesia can be neutral or can cause an “El Nino” or “La Nina”.  The La Nina pattern generally results in drier than normal conditions for much of Kansas and the region.  The severity depends on how strong the La Nina is.  The long-range NOAA forecast is for equal chances of above or below normal precipitation and temperature.  If the La Nina strengthens we will likely be drier.
  • Why do soil moisture conditions matter? Briefly, wet soil cools faster than dry soil and to a greater depth.  The growing point for the 2018 wheat crop is below the soil surface until well past breaking dormancy in the spring.  This means that wheat can withstand extremely cold air temperatures since the growing point is protected.  When the soil is dry, especially without an insulating cover of snow, well-established wheat, or crop residue, it is more likely for soil temperatures to drop below freezing and possibly damage or kill the growing point.  When we experience true winter kill it is often the result of cold temperatures with dry soils.  And it isn’t just the cold temperatures but the condition of the wheat plant.  Wheat will “harden”, become winter hardy in response to decreasing day length and decreasing temperatures.  Part of the process is the production of compound in cells of the plant that are essentially antifreeze and protect plant cells.  Dry conditions lead to cells more vulnerable to damage when soil moisture is lacking.
  • So how is the wheat right now?  First, as the saying goes; “Wheat has nine lives.”  We still have at least eight left.  Well-established wheat with well-developed crowns and root systems can take a lot of stress.  The only caveat is that wheat that “overgrew” this fall is in a bit more jeopardy.  However, the crowns on the soil surface help insulate the soil and wheat.  A bigger concern is the late planted wheat, and there is a great deal of that.  This wheat lacks a well-developed root system or crown and is more vulnerable to damage.  It isn’t time to panic yet.  Even if some plant stand is lost, wheat has a strong adaptive capacity to compensate. 
  • What will help?  First some significant moisture would be great.  Second, seasonal temperatures will help keep what moisture we have and minimize plant stress.