Fall Grazing Management Influences Forage Production

Sep 20, 2022

Dry conditions are common across most of North Dakota with most areas receiving below normal precipitation over the last two months. This, in combination with above average temperatures, is impacting the condition of pastures across the state. Currently, the majority (59%) of pastures in the state are reported as being in fair or lower condition.

Grazing management in the fall can have significant impacts on forage production during the subsequent growing season.

“Pastures in our region are dominated by cool-season grasses, which can make up 85% or more of the species composition,” says Miranda Meehan, North Dakota State University Extension livestock environmental stewardship specialist. “These cool-season grasses can develop tillers in the fall, and the development of these tillers has a direct impact on plant growth the next year.”

“If livestock graze tillers below the growing point in the fall (in between the bottom two leaves), they usually will not survive the winter,” says Meehan. “Drought stress also affects the survival of fall tillers. Fall droughts either don’t allow buds to come out of dormancy, thus no new tiller growth, or cause death to those tillers that did grow. If tillers do not establish or survive the fall, a delay in growth and development will occur the following growing season due to new tiller development in the spring.”

Monitoring degree of use is one way to prevent negative impacts to developing tillers. The recommended utilization level for proper use of grasslands is 40% to 60%. At this level, rangeland utilization is fairly uniform, with 65% to 80% of the height of desirable forage species being grazed. Livestock should be removed when this level is exceeded.

An NDSU Extension study found that pasture with greater than 80% forage utilization had delayed forage growth and reduced forage production by as much as 57%. A full article about the study is available in the 2022 NDSU North Dakota Livestock Research Report.

The NDSU Grazing Monitoring Stick can aid in monitoring forage utilization on range and pasture. The grazing monitoring stick does require an ungrazed area with similar forage species for comparison.

Here are the steps for using the grazing monitoring stick:

Calculate the percent of the plant height removed by dividing the grazed height of the plant by the ungrazed height. Subtract this amount from 1.
Multiply this amount by 100 to determine the percent of height removed.
Correlate this number with those in the chart in the NDSU Extension publication “The North Dakota Grazing Monitoring Stick: A Way to Measure Range and Pasture Utilization” (https://tinyurl.com/NDSU-GrazingStick) to estimate the percent of entire plant weight removed.

“A general rule of thumb is to target 50% utilization by weight during a grazing period, as well as at the end of the grazing season,” says Kevin Sedivec, NDSU Extension rangeland management specialist. “If greater than 50% utilization occurs during a grazing period, plant recovery will be slower, which means plants require a longer recovery period between grazing events to maintain their health.”

High use of grasslands, especially in the fall, can result in tiller mortality by either removal of the growing point or physiological stress to cool-season grasses. If pastures receive high grazing use, they must be given adequate time to recover and turnout should be delayed on these pastures in 2023. If pastures are not given time to recover, forage production and pasture condition will decline.

“Monitoring pastures will be especially critical if dry conditions persist through the fall, as drought stress may increase tiller mortality,” says Sedivec.

Contact your NDSU Extension agent for assistance with monitoring grazing use and reviewing your grazing plan.

Source : ndsu.edu

Video: Turning Plant Defense Into a Management Strategy

Turning Plant Defense Into a Management Strategy

Understanding how a plant responds to stress is one thing.

Using that knowledge to make better management decisions is another.

Systemic acquired resistance, or SAR, is the plant's more direct defense response. When stress or infection occurs, the plant begins signaling throughout its system and preparing defensive compounds.

But if we know that response exists, can we help prepare the plant before the stress arrives?

The answer starts with understanding what triggers the response and what the plant needs to carry it out.

The Trigger and the Fuel

Salicylic acid plays an important role in triggering the SAR pathway.

Think of it as turning the truck on.

The engine may be running, but it still needs fuel to do the work.

In this case, manganese plays an important role in supporting the enzyme systems involved in the plant's defensive response.

This makes manganese status an important part of the conversation. Whether a producer is using tissue testing, sap analysis, or simply scouting for visible deficiency symptoms, the goal is to make sure the plant has adequate manganese available.

Manganese is required in relatively small amounts, but that does not make its role small.

If the plant receives a signal to defend itself but lacks the nutrition needed to support that response, it may struggle to carry out the process efficiently.

The trigger matters.

The fuel matters too.

Prepare Before the Stress Arrives

The best time to think about stress management is before the plant is overwhelmed.

Once a crop is already struggling, management can quickly turn into a game of catch-up.

This is similar to nitrogen management. Once a plant becomes severely deficient, correcting the problem does not necessarily erase the time and yield potential already lost.

Plant defense can work the same way.

Low-rate, targeted approaches designed to support the SAR pathway may fit best ahead of an expected stress event rather than after significant damage has already occurred.

That requires producers to think about predictable stress.

We may not know exactly what the weather will do tomorrow, but we generally know summer heat is coming. We know certain field conditions increase disease pressure. We know a herbicide application can temporarily stress a crop as the plant processes the chemistry.

Even a properly timed and labeled herbicide application can create a temporary response in the plant.

That does not mean the herbicide is bad.

Weeds can create significantly more yield loss than the temporary stress caused by controlling them.

The question is not whether we should eliminate every stressor.

The question is whether we can better prepare the plant to manage necessary and predictable stress.

Not All Stress Is Bad

Stress is a normal part of plant growth.

A perfectly stress-free environment does not exist in the field.

In fact, some stress is necessary for normal plant development. A plant responds to wind, temperature, moisture, sunlight, and countless other environmental signals throughout the season.

The environment is stress.

The plant's job is to manage it.

Problems begin when the stress load becomes greater than the plant's ability to respond.

Extreme heat, drought, high salt concentrations, disease pressure, and even certain management practices can add to that load.

This is where understanding SAR becomes useful.

Instead of waiting until the plant is visibly struggling, producers can begin identifying periods when stress is likely and make management decisions around those windows.

ISR Starts With the Soil

While SAR is a more direct defense response, induced systemic resistance, or ISR, brings the conversation back to soil health.

The longevity of a farm is closely connected to the health of its soil.

Carbon plays a major role because it supports biological life within the soil. Bacteria, fungi, and other organisms interact with plant roots and influence how the plant grows, accesses nutrients, and prepares for stress.

This is why soil health cannot be reduced to one product or one application.

It is a system.

Keeping living plants in the field longer can support biological activity. Cover crops may fit some operations. Better water management can improve soil conditions.