This webinar was recorded and can be viewed at: https://youtu.be/P4cYq-d_oh0. 

Drought conditions and unexpected events such as wildfire can significantly reduce available pasture for livestock. Irrigated annual forages provide a practical and flexible solution to maintain feed supplies and extend grazing seasons. By carefully selecting forage types, planting at the right time, and managing grazing effectively, producers can optimize both yield and forage quality. 

Annual forages are typically divided into cool-season and warm-season species. Each type has specific planting windows, growth patterns, and management strategies. Understanding how and when to use these crops is essential for maximizing productivity under irrigated conditions. 

Cool-Season Annual Forages 

Cool-season annuals are an excellent option for early spring or fall grazing. Common species include oats, spring triticale, spring barley, field peas, and annual ryegrass. These crops perform best in cooler temperatures and can be seeded in two primary windows: 

• Spring planting: Mid-March to mid-April (soil temperatures around 43–45°F) 
• Late summer planting: August through early September for fall forage production. 

 Due to the warm winter in Nebraska this year, soil temperatures have already reached the required threshold.

Seeding and Fertilizing for Cool-Season Annuals 

Typical seeding rates for small cereals like oats are around 2 bushels per acre, though producers should consult resources like NebGuide G2185 or local seed suppliers for precise recommendations. 

Always conduct a soil test before fertilization.  In general, apply 50–75 pounds of nitrogen per acre for spring small grains. 

Research from the University of Nebraska–Lincoln (UNL) indicates that seeding rate as low as 50 lbs/acre for “Goliath” oats does not reduce yield. However, environmental conditions, especially moisture and temperature, can cause large year-to-year differences in production. 

Irrigation for Cool-Season Annuals 

From April through mid-June, cool-season annuals typically require 8–9 inches of water (rainfall plus irrigation) to produce approximately 3 tons of forage per acre. 

Warm-Season Annual Forages 

Warm-season annuals thrive in warmer temperatures and are ideal for summer grazing. Common options include millet, sorghum-sudan hybrids, sudangrass, crabgrass, and teff. 

Planting Guidelines for Warm-Season Annual Forages 

Plant from mid-May through early August, when soil temperatures are 60–70°F. 

For fall grazing, plant no later than August 10. Late planting reduces yield potential, so timing is especially important. 

Seeding and Fertilizing for Warm-Season Annual Forages 

Seeding rates vary widely depending on species and seed size (see NebGuide G2183).  

It is best to conduct a soil test before fertilizing. In general, apply 40–50 pounds of nitrogen per acre at planting. An additional application of 40 to 50 lbs. can be useful if moisture is adequate.  See Extension Circular EC 155 for more information on fertilizing. 

Warm-season crops generally produce higher biomass under irrigation, making them valuable during peak summer demand. 

Grazing Management of Annual Forages 

Proper grazing management is essential to maintain forage quality, encourage regrowth, and minimize waste.

General Grazing Principles 

• Begin grazing at the appropriate height. 
• Use high stocking density and rotational grazing to keep plants vegetative (high forage quality), improve utilization, and regrowth. 
• Expect some inefficiency compared to haying due to trampling losses. 
• All annuals can accumulate nitrate, especially under drought or high nitrogen fertilization. See the article Reducing Nitrate Concerns when Grazing Forage Cover Crops for management strategies to mitigate nitrate toxicity. 

Grazing Cool-Season Annuals  

• Begin grazing at 5–6 inches of growth. 
• Maintain heights below 10 inches to prevent maturity. 
• Rotational grazing with three or more paddocks is recommended.  

Stocking rates depend on potential hay yield. For example, for a 45-day grazing season: 

1.5 tons of hay/acre: ~0.85 cow-calf pairs per acre (1.92 AUM/acre) 

2.5 tons of hay /acre: ~1.42 pairs (3.21 AUM/acre) 

3.5 tons of hay /acre: ~1.99 pairs (4.49 AUM/acre) 

Grazing Warm-Season Annuals 

 Two good warm season options for summer grazing are sudangrass or sorghum-sudan.  

• Begin grazing when plants reach about 2 feet tall, as this reduces prussic acid risk. Typically graze 30–45 days after emergence. 
• Graze down to 8 inches to promote regrowth. 
• Rotational grazing with three or more paddocks is recommended.  
• When targeting 3 months of grazing, stocking rates should be around 1 cow-calf pair per acre, though irrigated systems with good fertility may support higher densities. 

Managing Quality  

 The quality of both cool-season and warm-season annuals can be good enough to meet the needs of lactating cows, if these forages are maintained in immature states. If forages begin to mature, pulling some of the land out of the grazing rotation may be desirable to increase stocking density and allow the forage that is being grazed to remain immature. The area that is pulled out of the rotation can be hayed, used for silage or can be swathed to preserve the forage, and the swaths grazed later. For example, three of four paddocks are grazed. The fourth paddock is left ungrazed- hayed or swathed for windrow grazing in the fall/winter. 

Extending the Grazing Season  

A double-cropping system with two fields can provide season-long forage availability when using annual forages. For example: 

Field 1: 

Winter annuals planted in fall (Oct)→ graze April to late-May 

Warm-season annuals planted late May → graze July to September 

Winter annuals replanted in fall → graze next spring 

Field 2: 

Cool-season annuals planted early spring → graze late May to early July 

Cool-season annuals planted mid-summer → graze fall  

This approach can extend grazing from mid-April through late November. 

A comprehensive table of guidelines for establishment of annual forages in Nebraska including seeding rate, seeding depth, planting date and their grazing value can be found in the article Planting Annual Forages. 

Forage Mixtures 

Mixing warm- and cool-season species at the same time in spring plantings are generally ineffective, due to differing growth requirements.  

However, planting mixtures of winter and spring cool-season annuals in late summer can provide fall growth, plus spring regrowth for fall and spring grazing. Examples include: cereal rye + oats, cereal rye + turnips, winter triticale + oats. For more information, see the article Mixed Seeding of Winter and Non-winter Hardy Annual Forages. 

Economic Considerations 

Fertilizer costs play a significant role in forage production decisions. While reducing nitrogen application lowers costs, it also reduces yield. Run the economics to see if the nitrogen cost is offset by yield. Usually, the first 30 to 40 lbs. of nitrogen provide the biggest yield benefit. Producers must balance input costs with expected forage gains to optimize profitability. 

Conclusion 

Irrigated annual forages offer a powerful tool for cattle producers facing drought, pasture loss, or seasonal forage shortages. By selecting appropriate species, planting at optimal times, and implementing effective grazing strategies, producers can maintain productivity and extend the grazing season.  

While environmental conditions introduce variability, thoughtful planning and diversified forage systems can provide consistent and reliable feed resources year after year. 

This webinar was recorded and can be viewed at: https://youtu.be/P4cYq-d_oh0.