Wallaces Farmer

Learn to manage drought-stressed pastures

It’s time to start evaluating pastures and prepare them for the 2021 grazing season.

March 16, 2021

4 Min Read
Pasture suffering from drought
VIGILANCE NEEDED: Going forward, growers should continue to monitor pasture and drought conditions regularly to provide direction in how to proceed this spring with turnout, seeding, fertilization and weed control. Curt Arens

Given two years of inclement weather, cattle producers should start evaluating pastures and consider how to prepare them for the 2021 grazing season. Below are answers to common questions concerning pastures during a drought:

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 droughtmonitor.unl.edu. Persistent drought is predicted in western Iowa. It is hoped that conditions will improve with spring moisture.

What is the subsoil moisture? Subsoil measurements taken last fall at Iowa State University sampling sites in northwest Iowa ranged from 1.5 to 6 inches of moisture in the top 5 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? It 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 or 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.

Going forward

Take these actions to safeguard your pastures:

Monitor drought conditions regularly. This will provide direction in how to proceed this spring with turnout, seeding, fertilization and weed control. A weekly drought map is also available at droughtmonitor.unl.edu.

Check forage stand for plant vigor and density. If drought conditions improve, consider frost seeding red clover or interseeding drought-tolerant species. If the plant stand is poor, it may be necessary to establish a new seeding. But for any method of seeding to be successful, there must be sufficient and continuous moisture.

Consider fertilization to boost pasture grasses. Grasses respond well to 60 to 100 pounds of nitrogen per acre, as long as soil pH, phosphorus and potassium levels are adequate. If drought conditions persist this winter, consider applying half of the N in early spring and the other half in August if moisture levels improve.

Delay turnout until forage is 6 to 8 inches tall. If forage plants are grazed too soon, this will weaken existing plants, delay future growth and increase weed competition.

Think about weed control. There are basically two ways to do this — provide competition with desirable species of pasture plants, or use chemical or mechanical control.

Avoid overgrazing. Move the cattle to a new pasture when the forage height is no shorter than 4 inches and allow a minimum of 21 days for cool-season grasses to regrow in late spring and early summer. In mid- to late summer, the number of days needed for regrowth may expand to six weeks or more.

Consider planting summer annuals to spare pastures. ISU Extension has a publication, "Selecting Forage Species," which lists the characteristics (including drought tolerance) of various species. It is available at ISU Extension store.

Realize there is no magic bullet. Regardless of what is considered or planned, success ultimately hinges on timely rains and growing degree days. If drought continues, forage insurance may be warranted.

Doran is an Extension beef specialist at Iowa State University.

Source: Iowa Beef Center, which is responsible for the information provided and is wholly owned by the source. Informa Business Media and its subsidiaries aren't responsible for any of the content contained in this information asset.


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