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Virginia Cooperative Extension - Knowledge for the CommonWealth

Crop and Soil Environmental News, September 2001

Does Annual Ryegrass Fit into Virginia's Pasture Systems?

Chris Teutsch
Extension Forage Specialist
Southern Piedmont AREC

Ray Smith
Extension Forage Specialist

Annual ryegrass (Lolium multiflorum) is a cool-season annual bunchgrass that originated in Southern Europe. It is widely adapted and can be found throughout the world. In the United States, annual ryegrass is grown on close to 3 million acres. The majority of this acreage is found in the southeastern United States where annual ryegrass is utilized for winter pasture. Most annual ryegrass is sodseeded into permanently established warm-season grasses in order to extend the grazing season.

Annual ryegrass is both highly digestible and extremely palatable making it a desirable species to include in forage systems. In addition, annual ryegrass has high seedling vigor making it well adapted to either conventional or no-till establishment. Under good growing conditions, annual ryegrass can produce grazable forage in as little as 45 days after establishment. Annual ryegrass also possesses excellent yield potential. Many of you may prefer to stay with cereal rye for an annual cool season pasture, but annual ryegrass provides a new, high quality option.

Annual Ryegrass in Virginia

A recent variety trial conducted at Virginia Tech's Southern Piedmont Agricultural Research and Extension Center showed that annual ryegrass is capable of producing more than 7500 lb DM/ A when no-till seeded into a bermudagrass sod (Table 1). Although these results were taken from only one year, they represent the potential forage production and quality of annual ryegrass. The crude protein concentration at the first harvest ranged from 15.7 to 16.4% and did not differ between varieties (Table 2). The acid detergent fiber ranged from 21.7 to 25.0% and was significantly lower for Tetraplus (Table 2). The first harvest accounted for 40-45% of the total yield.

Table 1. 2000-2001 dry matter yields for annual ryegrass variety trial located at the Southern Piedmont Center, Blackstone, VA.

Variety Company Dry Matter Yield
    4/18/01 5/11/01 5/31/01 6/19/01 Total
    ---------------------------lb/A--------------------------
Passerel Pennington Seed 3443 1724 1040 1552 7759
TAM90 Texas A & M 3940 1543 924 1323 7730
Big Daddy Southern States 3294 1799 940 1345 7377
Tetraplus EverGreen Seed 2972 1070 1259 1618 6919
LSD (0.05)   367 221 159 230 550

Table 2. 2000-2001 crude protein, neutral detergent fiber, and acid detergent fiber for annual ryegrass variety trial located at the Southern Piedmont Center, Blackstone, VA.

Variety Crude Protein Neutral Detergent Fiber Acid Detergent Fiber
  4/18 5/11 5/31 4/18 5/11 5/31 4/18 5/11 5/31
  -----------------------------------------%----------------------------------------------
Passerel 16.2 17.9 25.3 45.7 44.2 48.5 24.3 22.5 20.9
TAM90 15.7 17.5 24.2 47.0 44.3 50.6 25.0 22.4 22.3
Big Daddy 16.4 17.2 25.3 44.2 47.0 48.8 23.4 24.0 21.0
Tetraplus 16.2 19.9 27.0 42.2 42.5 45.6 21.7 20.9 18.7
LSD (0.05) NS 1.6 1.3 2.1 0.6 2.0 1.6 0.8 1.5

These data indicate that annual ryegrass yields well and produces high quality forage in Virginia, but where does it fit into our pasture systems? The most logical fit is utilizing annual ryegrass to overseed permanent warm-season pastures. This increases land use efficiency and total forage production. Bermudagrass is well adapted to the Southern Piedmont and Coastal Plains Regions of Virginia and provides an ideal sod for overseeding with annual ryegrass.

Annual ryegrass may also be used to interseed weak cool-season grass sods. Although this use of annual ryegrass provides high quality forage quickly, it does not replace the need for pasture renovation and sound management practices. A third use of annual ryegrass may be planting in rotation with a summer annual crop such as crabgrass, millet or sorghum. This option has a significant cost associated with the establishment of two annual crops. In addition, a significant risk of stand failures due to inconsistent rainfall in late spring exists for the summer annual crop.

Establishment

Since annual ryegrass germinates rapidly and has excellent seedling vigor, it is well adapted to both conventional and no-till establishment. If existing grass is actively growing then sod supression is important when no-till seeding. This may be accomplished by close grazing prior to establishment and/or using a light rate of a burn down herbicide such as paraquat. When warm season grasses are dormant then no sod suppression is necessary. Pastures should be overseeded at rate of 30 to 35 lb/A in mid August to mid November. Seeding rates of up to 50 lb/A have been used (primarily by dairies) to increase stand density for management intensive grazing or haylage harvest. Areas in the Northern Piedmont and west of the Blue Ridge Mountains should use the earlier seeding date. When using conventional tillage, seed should be broadcast and cultipacked on a fine, but firm seedbed. Since the seed size of ryegrass is relatively small, the seeding depth should never be greater than _ inch.

At seeding, apply phosphorus and potassium according to soil test and nitrogen at a rate of 20 to 50 lb/A depending on the seeding date. Earlier seeding dates allow for increased fall growth and therefore require higher nitrogen rates. Later seeding dates use less nitrogen in the fall. When seeding into a bermudagrass sod, there may be significant competition for starter nitrogen if the sod has not gone completely dormant. In this case an additional application of 20 to 30 lb/A may be required in the fall.

Fertilization

Annual ryegrass responds well to nitrogen fertilization and can utilize up to 250 lb N/acre per year. A general guide is to apply up to 50 lb/A at seeding, 50 to 75 lb/A in early spring, and 50 lb/A following each harvest. Early spring nitrogen stimulates early growth allowing for earlier grazing. When annual ryegrass is interseeded into a bermudagrass sod, latter nitrogen applications can be increased to stimulate bermudagrass growth.

Harvest Management

New seedings should be allowed to reach a height of 10-12 inches before grazing or clipping. Early fall seeding can produce significant growth and should be grazed or clipped to 3-4 inches to prevent matting during the winter months. Excessive matting can delay or reduce spring growth. In early spring, the plant is in the vegetative phase of growth and the apical meristem (growing point) is safely located below the grazing height. In this stage, grazing should be initiated at a height of 8-12 inches and terminated at 2-6 inches. As the plant matures, the vegetative growth changes to reproductive growth, stem internodes elongate and the growing point is elevated. At this stage grazing should be deferred until the early boot stage. This will allow for rapid regrowth from the crown buds.

When annual ryegrass is utilized as a short-lived annual, close and frequent grazing can be a better fit for most forage systems. This is especially true when annual ryegrass is sodseeded into a warm-season perennial pasture. In this situation close grazing in late spring is needed to reduce competition and allow the warm-season species to initiate growth.

Winter Survival

Some annual ryegrass varieties are susceptible to winterkill. Check with your seed supplier to make sure that the variety you purchase will survive the normal winter conditions in your area. Virginia Tech will continue to conduct research trials over the next few years to determine the best varieties for the state.

Summary

Annual ryegrass has the potential to produce ample high quality forage in Virginia. It is most effectively utilized to overseed permanent warm-season pastures in the Southern Piedmont and Coastal Plains Regions of Virginia. It can also be utilized to overseed weak stands of cool-season grasses in other areas of Virginia. While annual ryegrass can produce high yields of excellent quality forage, it does require significant inputs and should be considered an option only when permanent pastures are being effectively managed.

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