Fall Pasture Management: Care taken during fall grazing ensures grass growth the following spring

As livestock producers move herds from summer range to fall pasture, they are reminded to be vigilant when determining stocking rates and carrying capacity to ensure pastures aren’t overgrazed throughout the next few months, especially in areas facing ongoing drought conditions. 

Grazing intensity and grass growth 

During 2021-23, North Dakota State University (NDSU) Extension evaluated the impact of grazing use intensity on the growth and production of grasslands the following year at 51 locations in 12 counties across North Dakota. 

In an article titled “NDSU Extension Evaluates Impacts of Grazing Use on Grassland Growth and Production” and originally published in the 2023 North Dakota Livestock Research Report, Lead Authors Miranda Meehan and Kevin Sedivec note, with the exception of Kentucky bluegrass, the highest growth occurred in pastures with slight to moderate use, while pastures with severe use saw reduced forage production by as much as 57 percent in 2022 and 54 percent in 2023.

“The results of this program demonstrate the importance of having a grazing management plan and monitoring grazing use to reduce long-term impacts to grazing resources,” Meehan and Sedivec write.

In accordance with NDSU’s findings, as well as recommendations published from university Extension specialists across the nation, producers are advised to keep livestock from grazing grasses below three to four inches of stubble height.

Penn State Extension explains during the fall, cool season perennial grasses develop new shoots and go through the process of root regeneration, in which carbohydrates are stored to provide necessary nutrients for the plant to survive cold winter months and grow the following spring.

“These carbohydrates are stored within the crown and roots of the plant, which is generally in the lower three to four inches in cool season perennial pastures, so it is critical pastures are never grazed below a three to four inch stubble height at any point in the season but especially during the fall,” states Penn State Extension. 

“It is often recommended to leave a higher stubble height – often four to five inches – in the fall to give pastures a chance to store these carbohydrates which will give them a ‘jump start’ the following spring,” the article continues. “If plants are grazed below the growing point, nutrient stores will be depleted and the protection from stress will be dramatically reduced.”

South Dakota State University (SDSU) Range Management Field Specialist Sean Kelly reiterates this sentiment in a 2023 SDSU Extension publication, stating, “During the fall green-up, cool-season grasses are storing their energy reserves to ensure health through the dormant season and vigor next spring when the growing season starts again. If these shoots are overgrazed, the growing point can be removed, and it will not continue to grow next season.”

An article written by University of Minnesota Extension Forage Specialist Craig Shaeffer further notes, “Perennial ryegrass, orchardgrass and timothy store energy in stem bases and are especially susceptible to combined stress of overgrazing and drought, while alfalfa, smooth bromegrass, quackgrass and reed canarygrass are more tolerant. Shallow-rooted species like Kentucky bluegrass and red clover are also damaged by overgrazing.”

Proper stocking rates

In order to avoid overgrazing pasture this fall, it is critical for producers to calculate proper stocking rates. 

First, NDSU suggests figuring out how much forage is required by the animals grazing the pasture. 

To do this, multiply acres of vegetation type by the recommended relative production values to determine total production.

Then, multiply total production by the appropriate harvest efficiency for available forage for grazing. Divide this amount by 913 – the amount of air-dried forage consumed by one animal unit per month (AUM) to determine total AUMs available. 

Although it is not always an easy decision, Shaeffer notes producers with less available forage may need to consider reducing the number of animals on pasture to stretch feed supplies.

“This can be achieved by culling cattle from the grazing herd and/or relocating livestock to a drylot or sacrifice paddock and feeding them hay,” he says. “Assess feed costs and cull prices to determine the most cost-effective solution.”  

Forage management strategies  

Once stocked, it is essential for producers to continue assessing and managing fall pasture as time passes. 

NDSU Extension suggests using a grazing monitoring stick, which can serve as a user-friendly tool to measure and monitor pasture utilization – the percent of the plant removed by grazing animals – which can determine livestock removal dates and prevent overgrazing.

“As a general rule of thumb, proper utilization is achieved when 50 percent of the total plant weight – not height – of the key species has been utilized,” explains Meehan in a 2021 NDSU publication titled “The North Dakota Grazing Monitoring Stick: A Way to Measure Range and Pasture Utilization.” 

“Due to differences in structure, the height of removal will vary among species, so knowing the key forage species on pasture and rangeland is important,” she continues.

To use the monitoring stick, NDSU recommends placing the stick upright, without it leaning and measuring the leaf height of the key grass species in the area grazed. 

To do this, producers should choose a plant that is representative of other plants in the area, be sure to evaluate the current year’s green leaf growth and avoid measuring to the top of the inflorescence.

Then, repeat step two in an ungrazed area to calculate percent removal.

Additionally, Shaeffer suggests giving fall pastures ample time to rest.

“Even if pastures start to green up after some precipitation, drought-stressed plants are likely not strong enough to withstand regular grazing,” he says. “Giving livestock access to a pasture before it has sufficient time and moisture to make a full recovery can reduce stand persistence.”

Shaeffer adds, “It takes four to six inches of water to produce a ton of cool-season grass or alfalfa. Smaller amounts of rainfall may stimulate regrowth, but grazing of tall-growing grasses should be delayed until there is eight to 10 inches of regrowth. While grazing regrowth before plants reach these minimum heights may provide forage, it can weaken plants and reduce the long-term productivity of the pasture.”

Shaeffer also notes some weed species are able to take advantage of drought conditions and proliferate when cool-season forage goes dormant, so applying herbicide to eliminate weeds – preferably around a rainfall event – is good practice.

Hannah Bugas is the managing editor of the Wyoming Livestock Roundup. Send comments on this article to roundup@wylr.net.