Key Factors for Successful Forage EstablishmentWritten by Anowar Islam
By Anowar Islam, UW Extension Forage Agroecologist
Forage stand establishment relates to several important factors. For example, returning to forage production, increasing forage yield and desirable species, and improving sustainability and profitability.
Establishment success involves an understanding of the needs of forage and of several proven seeding methods. The basis for several years’ production is determined within two to three weeks after planting. Forage seeding is costly, especially perennial forage seedings, which are more expensive than other crops. The failure rate of forage seedings is higher than any other traditional crop seedings, and therefore the risk and cost of forage establishment are substantial.
Thin and poorly established stands encourage weeds to invade, reduce forage yields, and, in the long run, shorten life of the stands. Considering all these negative consequences along with the risk and cost associated with poor forage stand establishment, it is essential to maximize the chances of success.
There are a few key factors that need to be considered for successful forage stand establishment.
Remember, “half the job is planning.” Good, thoughtful pre-planning is the number one key for successful stand establishment.
A number of activities that should be completed well in advance before establishing a new forage stand include site selection, weed management, adjusting soil pH, fertilization, and species and variety selection. Once the forage is seeded, there are very limited options for controlling weeds. Soil pH adjustment is also very important. Many forage species can grow at a pH below 6.0; however, they will grow best and yield most at near neutral soil (pH closer to 7.0).
Correct selection of species and varieties is very important. Matching forage species or varieties to the characteristics of the soil is very important. Type of soil, soil texture, soil pH (e.g., acidic, alkaline, sodic), soil fertility, water holding capacity, drainage and cold tolerance all have effects on the selected forage species or varieties.
Care should be taken in selecting forage species or varieties without any biases. Unbiased, research-based information can be obtained by contacting neighbors who had success or extension personnel (e.g., UW Cooperative Extension educators or specialists). Species and varieties are often selected based on personal or industry preferences without considering the site characteristics and soil properties. Mistakes made in the early planning and management phase cannot be corrected later. So, always remember the “seven Ps” – pre, prior planning prevents pasture poor performance.
Weed management strategy during forage establishment is extremely important and needs to be developed and implemented long before the crop is seeded. Effects of residual herbicides from previous crops must be considered in this strategy. Without an adequate weed control program, weed pressure along with hot and dry temperatures make spring forage establishment difficult.
Planting alfalfa immediately after destroying old alfalfa stand should be avoided. Alfalfa produces chemicals that retain in the soils and can cause damage to new alfalfa seedlings. Affected plants may appear normal, but, in the long-term, yield reduction will occur.
Seeding at Proper Time
It is better to plant forage seeds at the time when odds are the best based on rainfall patterns and temperatures. For proper germination, 40 degrees Fahrenheit or higher temperatures are needed. Temperatures too warm are detrimental because the soil surface will not be kept moist. The most common month for forage planting in Wyoming is May. There are usually several weeks of good growing conditions by then; however, it can get hot by the end of May in some areas, and poorly-rooted seedlings desiccate resulting in poor stands.
An alternative to May seeding is generally late summer (August) if water is available. This is a good time for forage seeding, as weeds are less troublesome. Early spring planting refers to March or April, rather than May. This planting generally helps seedlings be better rooted before hot weather appears; however, slight frost injury, as with alfalfa, may occur due to hard frost after germination. Overall, there is less risk in early spring seeding than seeding in May (moisture stress) because of adequate rainfall and optimum temperature.
Dormant planting (a time in which conditions are such that seeds do not germinate) usually is November to March. This is common with perennial grasses in which seeds remain dormant in soil during the cooler months and get ready to germinate and grow as soon as conditions are favorable in the spring.
Recommendations for forage seeding rates vary considerably, depending on soil and environmental conditions. The larger the seed, the more pounds per acre are needed. As a general rule, these rates of seeding will result in about 20 to 50 seeds per square foot (20 for the larger and 50 for the smaller seeds). For example, 10 pounds of alfalfa seeds per acre will result in 50 seedlings per square foot – 50 seeds per foot of row with 12-inch row spacing; 25 seeds per foot of row with six-inch row spacing (seed every half inch).
If half of the viable seeds produce seedlings, a good stand is expected. If more than half establish, they will generally self-thin over the first three months or so to about 25 plants per square foot. Less than ideal soil conditions (such as uneven stony field, not well-prepared seedbed, etc.) might justify planting the higher end of the recommended range. Mortality will be greater with smaller-seeded forages than with larger seeds because of the initial less growth vigor in smaller-seeded seedlings.
Planting too deep is the most common reason for forage seeding failure. The rule-of-thumb in agronomy is not to plant a seed deeper than five times its diameter. This means most forage seeds should not be planted deeper than 3/8-inch. Depths greater than 3/8-inch will greatly increase the risks of poor emergence and thin stands.
A firm seedbed is critical to assure accurate seeding depths. Fluffy seedbeds interrupt the function of the depth band wheels of a seeder, and, as a result, seeds are frequently placed too deep.
Planting too deep is usually the result of a loose seedbed – it is sometimes hard to sufficiently firm a seedbed. Cultipacking or roller harrowing will help in leveling and firming soils. Planting too deep is probably not the most common reason for failure on no-till seedings (i.e., directly planting without seedbed preparation); however, not nearly as many acres are seeded with the no-till method. Sandy soils (such as in many areas in Wyoming) dry out faster; therefore, it is better to use the deeper (3/4- to one-inch) depth, particularly for grasses. Much research shows that the number of seedlings established sharply diminishes as depth of seeding increases from the optimum.
Forage seeds require ample amounts of water (about 100 percent of their own weight) to initiate germination process. This water must move from soil to the seed, so it is crucial the seed is in close contact with soil as much as possible. Good seed-to-soil contact will result in good and uniform germination and increase the number of productive forage plants in the seeded stand. A well-prepared seedbed without clods will ensure a good seed-to-soil contact.
To determine whether the soil is firm enough to plant, the following measures can be used: a footprint of an adult should not be deeper than ¼-inch on a well-prepared seedbed, and about 10 percent of the planted seeds should be on the surface of the soil after planting. No seeds visible on the surface indicate the planting was too deep.
Seeding With or Without a Companion Crop
A companion, or nurse crop, of a small grain or a small grain with pea mixture is commonly used with spring forage seedings in the northern U.S. This provides quicker ground coverage than forage seedlings alone, and helps reducing wind and water erosion and weed invasion during forage establishment. Also, companion crop provides forages in the establishment year. The decision for using a companion crop depends on the site-specific conditions including erosion potential, weed competition, and the producer’s forage needs during the establishment year.
Management of New Seedlings
Management of new seedlings is important for the longevity and productive stand of forages. For optimum growth of new forage seedlings, minimizing weed and insect competition, maintaining optimum soil fertility, and employing optimum harvest management play an important role over the life of the forage stand. Weeds commonly invade new plantings and may reduce forage stand if weed competition is not controlled. Clipping may be necessary, but it should not be done too early because this will remove only tops of the weeds, leaving active buds to produce new branches and more competition. On the other hand, too frequently clipping can reduce seedling development and, as a result, yield reduction may occur in the following year.