Considerations for Drought-Stressed Pastures

Given two years of inclement weather, cattle producers should start evaluating pastures and consider how to prepare them for the 2021 grazing season.
 
What is the current drought status?The U.S. Drought Monitor, which reports seasonal outlook for drought conditions for each state, can be viewed at https://droughtmonitor.unl.edu/ConditionsOutlooks/Outlooks.aspx.  Currently, persistent drought is predicted in western Iowa. Hopefully, conditions will improve with spring moisture.
 
What is the subsoil moisture?Subsoil measurements taken late fall at ISU sampling sites in Northwest Iowa ranged from 1.5 to 6.0 inches of moisture in the top five feet of soil – well below average. A “full” moisture profile contains roughly 11 inches of plant available water.
 
What was the grazing pressure last year?That depends. Were pastures continuously grazed, grazed with supplementation, or rotationally grazed? When pastures are overgrazed, weeds have less competition and can establish.
 
What forage species are in the pasture mix?Some species, such as smooth bromegrass and Kentucky bluegrass are more drought tolerant. Kentucky bluegrass goes dormant in drought but comes back well once conditions are favorable. In drought, smooth bromegrass may have just gone dormant. Realize, however, that bromegrass regrows from carbohydrate reserves stored in the lower stem, so cutting below 4 inches or grazing short does extreme harm to smooth bromegrass. Tall fescue and Orchardgrass are more susceptible to stand failure in extreme drought. A really rough rule of thumb for many, but not all, forages is that the more winter hardy a species is, the better the drought survival for that species.
 
Were the stands stressed?If so, plant health may be compromised, and spring regrowth will be delayed. “Stress delay” creates great conditions for no-till interseeding improved species because it reduces competition against new seeding development. But this assumes that winter/spring precipitation will create favorable conditions for planting. Frost seeding could also be tried in pastures that look like they are worth keeping.  But, it’s more hit and miss and never recommended if establishing a new pasture from scratch.
 
For more information or to ask questions on the topic, contact Iowa State University Extension and Outreach Beef Specialist Beth Doran at 712-737-4230 or doranb@iastate.edu.

Share |