A new year and quite a change in weather from January 2018.  Certainly much wetter and over the last few days, temperatures have moderated.  No drought in the state with a few counties bordering Oklahoma experiencing dry conditions.  While there are certainly many meetings this time of year for producers, January is the relative calm before the storm for crop producers as they prepare for the 2019 cropping year.  It’s a good time to discuss what may be the major challenge facing Kansas agriculture, especially in Western Kansas, water.  First, a little background may help.  What is normal?  What is drought

Normal climate in Kansas varies greatly across the state.  The southeast corner of the state normally receives around forty inches of precipitation while at the Colorado border, twelve to sixteen inches is the long-term average.  The length of the growing season is similarly varied from approximately over six months in the southeast to a little over four months on average in the northwest.  Humidity, wind, and even cloudiness also vary across the state.  Potential evapotranspiration (PET), the amount of water lost from land and bodies of water and through plants if water wasn’t limiting also varies as the result of these climate factors.  PET is lowest in the southeast and increases as you move west and is highest in the southwest.  The reasons for this variability include changes in elevation, the rain shadow of the Rocky Mountains for western Kansas, the Gulf of Mexico, and the tracking of the jet stream.   All of this determines climate.

For simplicity, let’s look at Western Kansas.  Here we are on the border of humid with semi-arid to the west.   Long-term, humid indicates a climate where overall the amount of precipitation equals or exceeds the PET for the year.  Water should be adequate overall for crops without extended periods of moisture shortage.  That doesn’t mean no plant stress but limited and short-term stress on average.  Remember this is an average and droughts will occur.  For the semi-arid area in the west, it denotes that typically, PET exceeds precipitation most years.  In English for crop producers, the demand for evaporation and transpiration exceeds the available moisture for significant periods during the year.  All of this determines a variety of factors from adapted crops to the proper varieties/hybrids for a region and many cultural practices such as planting date.

Now, what is a drought?  There is no one totally agreed upon definition.  For a meteorologist it is a significant decrease from precipitation from what is normally expected.  Therefore, if we receive our normal 28 inches we aren’t in a drought.  In Southeast Kansas, that is only 66% of normal so a drought occurred.  For a hydrologist, it is a lack of surface and subsurface waters.  For crop production, it is a lack of soil moisture to meet cropping needs.  This is what the drought monitor from Lincoln Nebraska measures.  And for producers, it is much more complicated than this.  When rain falls matters as much as how much.  Temperature, wind, and humidity also factor in as does the cultural decisions a producer makes.

Next week, where does the water we use come from and who is using it?