Stockpiling Cool-Season Grasses with Fall Nitrogen Applications

Stockpiling cool-season grasses is a widely recommended forage management practice that helps extend the grazing season and reduce reliance on stored feeds during winter. This method involves allowing grasses such as tall fescue, orchardgrass, and Kentucky bluegrass to grow during late summer and fall without grazing so they can be used later in the season.

Applying nitrogen fertilizer in late summer or early fall enhances the yield and quality of the stockpiled forage. The timing and rate of nitrogen application, along with the choice of grass species, are key factors that influence the effectiveness of this approach. The application of nitrogen (N) to increase forage dry matter (DM) is well documented (Collins & Balasko, 1981; Gerrish et al., 1994; Riesterer et al., 2000; Scarbrough et al., 2004; Teutsch et al., 2011).

By combining fall nitrogen applications with proper grazing management, livestock producers can improve pasture productivity, reduce feed costs, and support more sustainable forage systems.

Tall fescue is commonly considered a versatile and persistent perennial forage for grazing livestock. It is the most desirable grass to stockpile for late-fall and winter grazing. During the fall, this grass produces higher yields of stockpiled forage of superior quality compared to most other temperate grasses. The fall-saved forage is very palatable and high in digestibility (high in soluble sugars). Forage-quality losses from leaf deterioration after frost are lower for tall fescue compared to most other forages.

In southern Ohio, tall fescue will stay green and may even grow a little during warm winter days. Tall fescue forms a strong sod tolerant of trampling damage, which is common on wet pasture soils during the winter. Winter grazing has minimal influence on the yield or quality of this grass in the following season.

Tall fescue has a bad reputation among many Ohio producers because animals do not graze it readily during the summer months. Some of this reduced summer palatability is associated with the presence of an endophyte fungus, Neotyphodium coenophialum, in the plant. This fungal endophyte produces alkaloids toxic to animals which cause various animal health problems. Many existing fescue stands are endophyte-infected, but the level of infection varies considerably. Animal health problems associated with endophyte-infected stands occur primarily in the summer when animals are under heat stress. Adverse health effects are less common on infected-fescue pastures in the fall and winter. The toxin produced by the fungal endophyte is less concentrated in leaf tissue than in the seedheads and stems, so the amount of toxin consumed in the fall is less than in the spring and early summer. The cooler temperatures in the fall and winter reduce the heat-stress problems associated with endophyte-infected fescue.

Endophyte-free cultivars are available which are equal or superior to endophyte-infected cultivars in yield, quality, animal preference, and stockpiling. Persistence can be maintained with a high level of management. New cultivars have a novel endophyte that can be as aggressive as infected fescue, but they do not contain ergovaline—the alkaloid that causes livestock health problems.

Considerations for Stockpiling

Two components to consider when planning to stockpile tall fescue are the desired level of forage quality and yield. Each producer should consider feed requirements and determine whether high-quality forage is needed for young animals, stockers, and lactating animals, or if a maximum yield is required to stretch limited stored-feed supplies. Important management factors affect the balance between the yield and quality of stockpiled fescue:

1. date of the last summer harvest or clipping (when to begin stockpiling)
2. nitrogen application date
3. nitrogen application rate
4. amount of legume in the pasture.

When to Begin Stockpiling

The last-summer harvest or clipping should be timed so that stockpiled tall fescue growth can begin by mid-July in northern Ohio and by August 1 in southern Ohio. These dates provide the best compromise between the yield and quality of stockpiled forage for fall and winter grazing. If higher-quality forage is desired, perform the last clipping or harvest about two weeks later—early August in northern Ohio and mid-August in southern Ohio. If maximum yields are desired and the forage will be grazed in November or December, then make the last harvest or clipping earlier in the summer—July 1 in northern Ohio and July 15 in southern Ohio. The effect of the final summer clipping date on the yield and quality of stockpiled tall fescue is illustrated in results from research in southeast Ohio (Table 1). Clipping the fescue in early July compared to mid-August increased yields for November grazing but resulted in slightly lower crude-protein levels.

Nitrogen Application Date

The date of nitrogen-fertilizer application can influence the yield and quality of the stockpiled fescue. In general, nitrogen should be applied when the stockpiling period is initiated (soon after the last summer harvest). If nitrogen is applied during early August compared with late September, yields can potentially be higher (Figure 1), but forage quality will be slightly lower (Table 2). If nitrogen is applied after mid-August in northern Ohio and late August in southern Ohio, less yield response can be expected in most years because of the shorter growing period (Figure 1). Forage yield and quality response to late nitrogen applications will depend on growing conditions during the fall.

Nitrogen Rate

Stockpiled fescue yield and quality are also influenced by the rate of nitrogen applied. In southeastern Ohio, nitrogen application improved forage yield (Figure 1) and quality (Table 3) compared with no nitrogen. The highest forage yields were obtained at 92 lb/acre of N and 200 lb/acre of urea; however, the additional yield improvement with applications above 50 lb of actual N per acre is usually not great enough to warrant the additional expense.

If fescue pastures are high in summer annual grasses, such as crabgrass or foxtail, nitrogen efficiency for tall fescue growth will be low. Summer-annual grasses growing vigorously in August have the potential to utilize the available nitrogen, leaving little for the fescue. The summer annuals die with the first killing frost, leaving very poor-quality feed while the nitrogen is immobilized (unavailable) in the slowly decaying weeds. Therefore, nitrogen fertilization for stockpiling should be limited to pastures with a vigorous fescue sod that are relatively free of summer-annual grassy weeds. Aspect also plays a role in choosing the field to stockpile. Choose a south- or southeasterly-facing slope that receives adequate warmth and sunlight during the winter months.

When applying nitrogen in the summer, keep in mind that some forms are subject to surface volatilization, which results in a loss of available nitrogen to the plants. Vitosh et al. (1996) recommends that urea-containing fertilizer should receive ½ inch or more of rainfall before hydrolysis occurs to reduce or eliminate volatilization losses. Urease inhibitor products such as Agrotain® (Agrotain International) are advertised to reduce such volatilization by lengthening the amount of time before such loss occurs. The most common urease inhibitor is NBPT (N-(n-butyl) thiophosphoric triamide), sold under the trade name Agrotain® (Schwab & Murdock, 2010). Do not use urea if the pasture has been surface limed within the past three months.

Pasture Legume Density

The need for late-summer nitrogen application on fescue-clover pastures should be evaluated in terms of the forage needs of each specific operation. Forage legumes can be used to economically improve the forage yield and quality of tall fescue pastures.

Red clover is an excellent legume species to frost seed or no-till seed into existing tall fescue stands every two years. Annual lespedeza is also an option in southern Ohio. Introducing legumes into tall fescue can reduce the need for nitrogen fertilizer, improve forage quality, and dilute the toxic effects of endophyte-infected tall fescue. Research in Maryland has demonstrated greater animal gains on fescue-clover pastures in the fall compared with pure tall fescue fertilized with nitrogen. But the nutritive value of a legume-dominant sward will deteriorate more rapidly with freezing temperatures than a fescue-dominant sward; therefore, stockpiled tall fescue-clover stands should be grazed earlier than pure tall fescue.

Late-summer nitrogen applications on fescue-clover pastures can be used to increase carrying capacity by stimulating more tall fescue growth that will be available for grazing well into the winter months. Missouri research demonstrates that red clover persists well in fescue pastures receiving late-summer nitrogen applications, provided nitrogen is not applied in the spring. In addition, Missouri research has indicated that a pasture composed of 50% legume dry weight responded the same as applying 60 units of nitrogen to stockpiled pastures.

Grazing Management

Grazing management is critical to efficient utilization of the forage. Managed grazing of stockpiled tall fescue in the winter will provide a good economic return because winter is the highest feed-cost time of the year. Livestock turned into a large pasture area will waste 60%–70% of the forage due to trampling and manuring of uneaten forage. Restricting access to a three-day supply of forage will likely double the number of grazing days. The following example demonstrates how to calculate grazing days per acre for a field with 4000 pounds of dry matter stockpiled. A 1,200-pound dry beef cow needs to graze approximately 3% of its body weight (36 pounds) per day. If grazing management is poor, approximately 35% of 4,000 pounds (1,400 pounds) is available for feed. This provides grazing for 39 days. If grazing is managed to achieve 70% utilization, then 2,800 pounds of dry matter will be available, providing 78 grazing days.

The forage yield and quality of stockpiled fescue decreases as the winter progresses. In late fall and early winter, nutritive value may be adequate to support good growth rates for weaned calves or stockers, but it rapidly becomes more appropriate as a dry cow feed. Crude protein levels may not decrease greatly, but total energy will decrease significantly from November to March. If the length of the stockpiling period among pastures is different, begin grazing the oldest material first before it becomes too deteriorated. If some areas have a significant amount of red clover, graze them early as well because red clover deteriorates more rapidly after frost than tall fescue.

Supplementation

Stockpiled tall fescue forage is likely to become deficient in some nutrients as the winter progresses. It may be necessary to provide supplemental energy and protein in late winter and early spring for animals with higher nutrient requirements. Mineral supplementation is normally recommended for animals grazing dormant forages. Monitor your animals’ body condition, the forage analysis of stockpiled pasture, and any hay being fed to determine the need for additional supplementation.

Management of stockpiled tall fescue is a key to cutting feed costs. Restrict access to a three-day supply of forage for November grazing. In early fall, the nutritive value of stockpiled fescue will most likely support weaned calves and stockers, but as winter progresses it becomes more suitable for dry cows. A mineral supplement is recommended for all animals grazing dormant forages.

Summary

Stockpiled tall fescue is an economical source of feed for beef-cow herds and sheep in late fall and winter. Fields used for stockpiling should be well-drained to decrease problems with mud during the winter-grazing period. Where possible, use stands that are endophyte-free. Improved varieties of endophyte-free tall fescue stockpile as well as older endophyte-infected stands. Also, choose areas that provide good shelter, preferably with a southeast exposure. Hay or other stored feed should be available, especially during periods of extreme cold, heavy snow, and ice storms.

Winter-grazing provides savings in feed and labor costs in caring for animals when good management practices are followed. Selecting the right combination of last summer harvest date, nitrogen rate, and nitrogen application date helps the producer tailor the tall fescue yield and quality to animals' nutritional requirements.

References

Collins, M., & Balasko, J. A. (1981). Effects of N fertilization and cutting schedules on stockpiled tall fescue. Forage yield. Agronomy Journal, 73(5), 803–807.
scilit.com/publications/16d8f2b059c1dda39533f337c5400e4c

Gerrish, J. R., Peterson, P. R., Roberts, & Brown, J. R. (1994). Nitrogen fertilization of stockpiled tall fescue in the midwestern USA. Journal of Production Agriculture, 7(1), 98–104.
doi.org/10.2134/jpa1994.0098

Riesterer, J. L., Undersander, D. J., Casler, M. D., & Combs, D. K. (2000). Forage yield of stockpiled perennial grasses in the upper Midwest USA. Agronomy Journal, 92(4), 740–747.
doi.org/10.2134/agronj2000.924740x

Scarbrough, D. A., Coblentz, W. K., Coffey, K. P., Harrison, K. F., Smith, T. F., Hubbell III, D. S., Humphrey, J. B., Johnson, Z. B., & Turner, J. E. (2004). Effects of nitrogen fertilization rate, stockpiling initiation date, and harvest date on canopy height and dry matter yield of fall stockpiled bermudagrass. Agronomy Journal, 96(2), 538–546.
acsess.onlinelibrary.wiley.com/doi/10.2134/agronj2004.5380

Schwab, G., & Murdock, L. W. (2010). Nitrogen transformation inhibitors and controlled release urea [PDF]. University of Kentucky College of Agriculture.
publications.ca.uky.edu/sites/publications.ca.uky.edu/files/agr185.pdf

Teutsch, C. D., Clapham, W. M., Fedders, J. M., Groover, G., & Tilson, W. M. (2011). Nitrogen rate and application timing affect the yield and risk associated with stockpiling tall fescue for winter grazing. Forage and Grazinglands, 9(1), 1–11.
acsess.onlinelibrary.wiley.com/doi/abs/10.1094/FG-2011-0513-01-RS

Vitosh, M. L., Johnson, J.W., & Mengel, D. B. (1996). Tri-state fertilizer recommendations for corn, soybeans, wheat and alfalfa. Extension Bulletin E-2567. Michigan State University Extension
canr.msu.edu/soilfertility/Files/Bulletins/Tri%20State%20Fertilizer%20Recommendations%20E2567.pdf