Maintaining Persistence and Productivity in Forage Stands

Forage producers face a constant balancing act. The goal is simple: produce high-quality forage while maintaining strong yields and long-lasting stands. But in practice, this balance can be difficult to achieve.

During a recent virtual conference session, Dr. Amanda Grev shared practical insights on how farmers can maintain both persistence and productivity in forage stands. Her message was clear: successful forage systems aren’t built on a single decision—they depend on a combination of sound management practices that support plant health over time.

Below is a focused summary of the key takeaways from the session.

The Three-Way Tradeoff in Forage Production

Most forage growers are familiar with the classic yield vs. quality tradeoff. Harvest earlier and you get higher quality forage but sacrifice some yield; harvest later and you gain more tonnage, but sacrifice quality.

However, Dr. Grev emphasized that there is a third factor farmers must consider: stand persistence.

If stands decline over time, productivity and forage quality will decline as well.

Poor persistence leads to:

• Thinner stands
• Increased weed pressure
• Lower yields and forage quality
• More frequent field renovation

Ultimately, weak persistence increases costs and reduces the long-term productivity of a forage system.

The goal is to manage forage systems so that yield, quality, and persistence work together rather than compete with one another.

1. Potassium: A Critical Nutrient for Stand Persistence

One of the first management factors Dr. Grev highlighted was potassium fertility.

Potassium plays a major role in helping forage plants tolerate stress. It supports:

• Disease resistance
• Winter survival
• Drought tolerance
• Carbohydrate storage in roots
• Overall plant health

Without adequate potassium, forage stands weaken quickly.

In trials comparing fertilized and unfertilized fields, stands receiving adequate potassium maintained strong production while potassium-deficient stands declined significantly within just a few years.

Why Potassium Deficiencies Occur

Forage systems remove large amounts of nutrients from the soil. Potassium removal is especially high when forage is harvested as hay or haylage.

For example, removing 3 tons of hay per acre removes approximately:

• 150 lb nitrogen
• 22 lb phosphorus
• 155 lb potassium

And six tons of hay doubles that removal!

If those nutrients are not replaced, soil fertility—and ultimately stand persistence—declines.

Grazing vs. Hay Systems

Grazing systems remove far fewer nutrients because livestock recycle nutrients through manure and urine. However, grazing introduces a different challenge: uneven nutrient distribution.

Animals tend to congregate near:

• Shade
• Water
• Gates
• Feeding areas

And where they congregate, they tend to eliminate. can create nutrient “hot spots” while other areas of the pasture remain deficient.

Good grazing management, with frequent moves and high stock densities, reduces stock congregating and helps distribute nutrients more evenly across the field.

2. Soil pH Matters More Than Many Producers Realize

Another key factor affecting forage persistence is soil pH.

Soil pH influences how well plants can access nutrients. When soils become too acidic, essential nutrients become less available to plants—even if they are present in the soil.

Most forage crops perform best at a pH between 6.0 and 7.0.

Some crops, such as alfalfa, require an even narrower range and are especially sensitive to acidic soils and performs best at pH 6.8 to 7.0

Low soil pH can also limit root development. Plants grown in acidic soils often develop weaker root systems, which reduces their ability to access water and nutrients during stressful conditions.

Maintaining proper pH through soil testing and liming is one of the most cost-effective ways to protect stand longevity.

3. Disease Pressure Can Reduce Stand Productivity

Forage crops are susceptible to numerous diseases, particularly fungal pathogens.

In orchardgrass alone, researchers have identified over 30 potential fungal diseases.

Common examples include:

• Rust
• Leaf spot
• Scald

These diseases reduce plant energy reserves by feeding on carbohydrates within the plant tissue. The result can include:

• Lower forage quality
• Reduced yield
• Decreased palatability
• Weakened plants

Disease pressure often increases when plants are stressed by factors such as:

• Poor fertility
• Drought
• Insect damage
• Excessively wet conditions

Management strategies that reduce disease pressure include:

• Selecting disease-resistant varieties
• Maintaining adequate fertility
• Harvesting stands on time
• Improving airflow within the canopy
• Rotating crops

4. Overgrazing is One of the Biggest Threats to Persistence

Grazing management also plays a major role in determining how long forage stands last.

A common problem is overgrazing.

Plants that are repeatedly grazed too short do not have enough leaf area to capture sunlight and produce energy for regrowth.

Studies comparing grazing heights show dramatic differences in plant recovery:

• Plants grazed too short regrow slowly and become stressed.
• Plants given adequate residual height recover faster and maintain stronger root systems.

Research suggests that maintaining approximately 3 inches of residual height often provides the best balance between productivity and persistence.

Allowing adequate recovery time between grazing events is equally important. Plants that receive proper rest periods build stronger roots and maintain higher energy reserves.

5. Cutting Height Matters in Hay Production

The same principles apply to hay systems.

Modern disc mowers are capable of cutting extremely close to the ground. While this may seem beneficial for capturing more forage, cutting too low can damage stand persistence.

Forage plants rely on two primary energy sources after harvest:

• Remaining leaf area for photosynthesis
• Stored carbohydrates in roots or lower stems

When stands are cut too low, both energy sources are reduced.

Studies show that stands cut at a 4-inch residual height regrow significantly faster than those cut at 2 inches.

In one study:

• 2-inch cuts required 64 days to regrow one ton of forage
• 4-inch cuts required only 40 days

In other words, leaving more residual often results in higher long-term productivity.

6. Weather Stress and Stand Longevity

Weather conditions also influence forage persistence.

Extreme stresses include:

• Drought
• Excess moisture
• Heat stress
• Winterkill

While farmers cannot control the weather, they can adjust management practices to reduce stress on plants.

For example:

Higher cutting heights help moderate soil temperatures and protect plant crowns during hot summer conditions.

Research has shown that even a few inches of additional residue can reduce crown temperatures by 10°F or more, improving plant survival during heat stress.

7. Harvest Timing and Root Energy Reserves

Harvest frequency and timing influence the amount of energy plants store in their roots.

After a cutting, plants draw on stored carbohydrates to begin regrowth. These reserves are not fully replenished until the plant reaches a more mature stage.

Repeated early cuttings can gradually deplete root reserves; weakening stands over time.

One practical strategy is to balance quality and persistence by:

• Harvesting early cuttings for higher quality forage
• Allowing later cuttings to mature slightly to rebuild energy reserves

This approach helps maintain both forage quality and stand longevity.

8. Weed and Insect Pressure

Weeds and insects can also contribute to declining forage stands.

Weeds compete with forage plants for:

• Light
• Water
• Nutrients
• Space

However, the best weed control strategy is often maintaining a dense, healthy forage stand. Many weed species simply take advantage of thin or stressed stands.

Similarly, insect damage tends to become more severe when plants are already weakened by other stressors.

Regular scouting and timely management are essential to keeping these threats under control.

The Big Takeaway: Persistence is About Management

Dr. Grev emphasized that declining forage stands are rarely caused by a single issue.

Instead, persistence problems usually arise from multiple stress factors working together, such as:

• Low fertility
• Poor grazing management
• Low cutting heights
• Heat stress
• Depleted root reserves

Strong forage systems come from consistent management across all these areas.

When farmers focus on soil fertility, proper harvest management, grazing discipline, and plant health, forage stands can remain productive for many years.

✔ Healthy stands produce more forage

✔ Persistent stands reduce renovation costs

✔ Strong management improves long-term farm profitability

In forage production, persistence isn’t just about keeping plants alive—it’s about building systems that keep delivering productivity season after season.