The keys to alfalfa stand establishment are summarized in the following statements. For additional information, see OSU Extension Circular E-949 (Alfalfa Stand Establishment Questions and Answers), or The Oklahoma Alfalfa Production Calendar at Oklahoma Alfalfa.

The objective of alfalfa stand establishment is to obtain about 30 vigorously growing seedlings per square foot before extreme weather conditions prevail (hard freezes in fall and high temperatures in spring). Good planning, along with some "art" and good farming practices, are critical to reliable stand establishment. Although the exact steps required for successful stand establishment vary from farm to farm and from year to year, there are several keys to alfalfa stand establishment that can be helpful. In several discussions of these keys, important cost factors are highlighted. A discussion of crop rotation with alfalfa, some special circumstances related to alfalfa stand establishment, and a general stand establishment budget are topics that overlap several of the keys.

Alfalfa roots can penetrate 25 feet in deep soils, and high yield and long stand life are attainable in sub-irrigated fields -- those with a water table between 5 and 20 feet deep. If, however, the water table rises to the surface during warm seasons, alfalfa grows poorly and may even die from scald within a few days  Scald often kills alfalfa plants when water stands during bright sunny days. Oxygen is unavailable to roots, and the water holds in heat. Scald usually occurs in thin stands or just after harvest when foliage does not shade the soil. This differs from root rots in that no pathogen is involved and no genetic resistance is available.

Waterlogged soils have poor aeration, inhibit nitrogen fixation, and encourage certain root rot diseases. Several adapted varieties are available with root rot resistance. They perform better in wet soils than susceptible varieties but cannot tolerate extended periods of standing water.

Much of the alfalfa in Oklahoma grows along creek and river bottoms that do not flood for prolonged periods of time. These alluvial soils are usually deep with good drainage, and fertility problems (if they exist) can be corrected profitably. Alfalfa will grow in shallow soils, but growth is usually reduced by rapid depletion of water in shallow root zones; thus, overall production will be less, and stand longevity will be shorter.

Avoid using sites that may have herbicide carryover problems. Alfalfa is very sensitive to picloram (sold as Tordon 22K) and the sulfonylurea-urea herbicides such as Ally, Glean, and Amber. Alfalfa is usually not listed as a rotational crop for these herbicides. When it is listed, there is a 22- to 34-month minimum rotational interval before alfalfa can be planted. Also, after application of several of these herbicides, alfalfa field bioassay must be performed before alfalfa can be safely planted.  The bottom line is herbicides used on previous crops can interfere with alfalfa establishment. So it is important to read and follow rotational restrictions and other information on herbicides labels before using them. Most pesticide labels, as well as Material Safety Data Sheets (MSDS) can be found on the World Wide Web.

Test soil and correct nutrient deficiencies and pH (acidity) before planting alfalfa. Nutrient deficiencies should be adjusted at least one or two months before planting alfalfa and pH (acidity) should be adjusted one year ahead. Alfalfa uses phosphorus, calcium, and potassium heavily. In some soils, these quantities are readily available; whereas in others, many nutrients must be applied.

The cost of lime and fertilizer (Table 3-3) may seem high, but cutting corners on these important factors puts the other activities in jeopardy. An inexpensive soil test ($10/sample) can save producers money by indicating which nutrients are deficient and by telling them what quantity should be supplied. This may help avoid the cost of unnecessary fertilizer. If soil analyses indicate the need for fertilizer and lime exceeds the high estimate, consider another site for alfalfa. Building up the fertility and pH over several years may be recommended. (See Chapter 4, "Fertilizing Alfalfa" for details.)

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Generally, the normal steps necessary for establishment of alfalfa include a primary tillage, disking, leveling, and smoothing. Primary tillage consists of moldboard plowing, chisel plowing or deep disking. Many producers believe that plowing at least eight inches deep is essential to bury crop residue and control weeds by burying growing plants and ungerminated seeds. OSU researchers found that deep disking can be used as a substitute for moldboard or chisel plowing in fields where surface drainage is not a problem. In soils that develop a hardpan, a chisel plow is commonly used to rip through existing hardpan layers.

Shallow disking normally follows primary tillage. Disking breaks up clods and is a good tool for incorporating crop residue, lime, and fertilizer. Soil conditions may require disking several times. An ideal seedbed is firm on the surface but loose enough in the root zone to allow rapid root penetration. Disking may be followed by spring-tooth and spike-tooth harrowing to further break clods and to help smooth the field. The final operation may be a corrugated roller or cultipacker to crush the remaining clods and finish firming the soil.

Working down a seedbed should be done when there is sufficient moisture in the soil so that it crumbles when worked. There is usually a short time after each rain when soil moisture is just right. Having moist soil 1-3 inches below the surface at planting is important; however, moisture at the surface is not important. Most successful alfalfa plantings are made when the seed is planted into dry surface soil. Moisture required for germination and initial seedling growth comes from rain or irrigation after planting. If the soil is dry to a depth of 4-6 inches, it may take several inches of rain to wet the soil enough for germination of alfalfa seeds.

If preplant herbicides are used, they must be applied when the seedbed is fairly fine (no clods greater than 1/2 inch) and incorporated with a disk, operated about four inches deep. At this depth, the herbicide is uniformly distributed in the top two inches. On the surface of the final seedbed, clods should be no larger than 1/2 inch in diameter, yet it should not be powdery. A seedbed is sufficiently firm when an entire footprint is visible but sinks no deeper than an inch, or if the impression of a tractor tire sinks no deeper than the tread bar.

On certain sandy or sloping sites, it may be desirable to maintain a significant amount of crop stubble and debris on the surface. This is especially important with sandy soils that are highly susceptible to wind erosion. Preplant incorporated herbicides should not be used on these sites.

Table 3-1 is a cost and earnings comparison of high-quality seed of a proven variety and low-quality seed of an unknown (but probably inferior) variety. The short term savings of $5 per acre resulted in an estimated loss of $200 per acre for a stand life of five years. This comparison is based on many years of observations of varieties and seed quality and does not include the added profits associated with longer stand life of proven varieties.

Alfalfa Varieties Test Results for Oklahoma: Personnel in the Plant and Soil Sciences Department through the Oklahoma Agricultural Experiment and Cooperative Extension Service, conduct alfalfa variety evaluations throughout the state to assist producers with decisions related to variety choices. Varieties are planted in replicated small plots, usually at research stations but occasionally in commercial alfalfa fields. Each plot is harvested and weighed at every cutting for at least three years. Each year, results of alfalfa variety tests are published and a recommended list is updated with descriptions of how they performed in Oklahoma.

The most recent summary of alfalfa variety performance in Oklahoma can be found at  Oklahoma Alfalfa Variety Testing on the World Wide Web. That site includes a summary of recent testing and a recommended varieties list. It also includes details of yields of experimental strains and released varieties in tests, showing yields for individual cuttings and total yields for a particular year, and a total over years of the test.

The recommended list of varieties includes those that have performed very well, and they have been tested for at least 10 or 12 test-years. This means each variety has been tested for up to three years at several sites. These varieties have the pest resistance necessary for Oklahoma, and it is highly likely these relatively new varieties will continue to do well.

Alfalfa seed should always be inoculated with live Rhizobium bacteria, specific for alfalfa. In some fields, with a history of alfalfa or sweetclover, alfalfa may not benefit from inoculation, but it is difficult to identify those fields before planting. After emergence, inoculation is risky, difficult, and expensive. Many strains of rhizobia are present in soil, and some may form nodules on alfalfa roots, but not all nodules fix nitrogen.

Certain brands of alfalfa seed are preinoculated (with or without lime coating). Two types of commercial inoculants are popular for on-farm application.

One type of inoculant has a dry clay sticking agent and requires no wetting
     of the seeds. Seeds should be mixed thoroughly with inoculant.

Peat-based inoculants need a sticker to help nodule-forming bacteria
     adhere to seeds. Commercial preparations of stickers and Rhizobium are
     available from inoculant manufacturers and do an excellent job. Some
     preparations contain up to 20 times the previously recommended number
     of bacteria. Closely following manufacturer's instructions normally
     produces the best results.

An alternative to commercial stickers for peat-base inoculants is to use milk or a water solution containing 10 to 20 percent table syrup or sugar. One pint is sufficient sticker for a bushel of seed. Moisten all seeds (in a concrete mixer, if possible), then add the inoculant. If the mixture is still too moist, add more inoculant, finely ground limestone, or powdery dry soil.

Heat, direct sunlight, and drying are all detrimental to the survival of rhizobia. For this reason, it is important to store inoculant in a cool place. Even with the large amounts of rhizobia initially applied, many bacteria may die during prolonged storage. Expiration dates are printed on inoculant packets and pre-inoculated seed tags. The date indicates when most of the bacteria will have died under normal storage conditions. Properly inoculated seed have thousands of bacteria per seed. Only one bacterium is needed to infest a seedling's root. Bacteria on seed in hot soil die a few at a time; nevertheless, even after 2 or 3 weeks there are usually enough live bacteria remaining to be effective.

If there are questions about the viability of bacteria on inoculated seed due to the length of storage and storage conditions, then seed should be reinoculated. For lime-coated seed, do not use water to moisten; fresh inoculant can be applied with mineral oil as a sticker (1/2 ounce of mineral oil per lb of seed).

Inoculant is normally included with higher priced seed. Cost for preinoculated seed is about five cents per lb more than comparable raw seed. Inoculant costs about a dollar per acre, if applied by the grower. Legumes can establish and survive without nitrogen-fixing bacteria, but plants cannot fix nitrogen. This means that without added nitrogen, plants will have a yellowish appearance and yields will be low. With high rates of nitrogen fertilizer application, uninoculated stands can be productive. Since inoculation is easy and cheap, it is probably the best insurance a farmer can buy. (For additional discussions see Chapter 4, "Fertilizing Alfalfa.")

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Spring Planting. In Oklahoma spring-planted alfalfa is usually not recommended since it is more risky than fall plantings. This is primarily due to more problems associated with strong drying winds, insects, weeds, and intense rains that tend to crust the soil. With spring establishment, planting between mid-March and mid-April is critical. This allows seedlings enough time to develop good root systems prior to the onset of high temperatures (above 90ºF). The use of multiple-pest resistant varieties, excellent seedbeds, and preplant incorporated herbicides are all critical with spring plantings. Spring planting is more likely to be successful in the eastern half of the state where rainfall is higher, and it can be successful statewide if irrigation is used. One should expect only one or two cuttings during the first summer from spring-planted alfalfa stands. Even in subsequent years, yields for spring-planted stands tend to be lower than those established in late summer. See Chapter 2, "Weed Management of Spring-Planted Alfalfa."

Whether planting in spring or fall, use 10-15 pounds per acre of pure live seed. Planting 10 pounds per acre of good alfalfa seed is equivalent to approximately 42 seeds per square foot, and proper planting of 10 pounds of seed per acre into a well-prepared seedbed should result in emergence of 25-30 plants per square foot. Most stands thin naturally during the first year to about 15-20 plants per square foot. Plant density will continue to decline and eventually stabilize at 5-8 plants per square foot in a full stand (25-35 stems per square foot).

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Placing the correct amount of seed at the proper depth in firm contact with the soil is the prime objective when planting alfalfa. A good way to reduce the cost of establishing alfalfa is to use only the amount of seed necessary and place it in a good environment.

This means that equipment must be properly calibrated to apply the correct amount. Planting insufficient amounts of seed increases the risk of stand failure, while planting too much seed is expensive and obviously wasteful. High planting rates are not good substitutes for poor seedbed preparation.

The following are common types of equipment used for successful alfalfa establishment.

Specialized drills have a box for small seeds and disk openers with depth bands to accurately place the seed 1/2 to 3/4 inch deep. Packer wheels firm soil over and around seeds. This type of drill is especially good on very firm seedbeds.

Double corrugated roller seeders drop the seed between corrugated rollers. The first roller breaks small clods and firms the seedbed. The second roller splits the ridges made by the first roller, covers the seed, and provides additional firming of the soil. While these are considered the best alfalfa seeders for most conditions, they may leave sandy sites vulnerable to wind erosion.

Grain drills, equipped with small-seed attachments, can accurately meter alfalfa seed. The major problem in using grain drills is controlling seed placement depth. If the furrow created by the drill is too deep, rain can wash soil into the furrow and cover alfalfa seeds excessively. Few seeds left on top of the soil develop into vigorous plants, even under ideal conditions. Allowing seed-drop tubes to wave from side to side leaves many seeds on the soil surface. Tubes can be tied so that seeds fall in front of press wheels; otherwise, rolling after the planter in a separate operation helps improve emergence percentages.

Pneumatic seeders, mounted on flotation-wheeled vehicles, can sow alfalfa fields rapidly and accurately. Seed is metered from a hopper and carried through tubes along booms (20 to 50 ft. long) with air. These machines work well on fluffy dry sandy soils that cannot be firmed by rolling. Seed is blown onto the soil from delivery tubes spaced 6 to 12 inches along the booms. Lightly packing, dragging a chain, or harrowing covers seed. The main advantage to this type of seeder is the rapid speed they can travel. Producers can plant several acres per minute, which may be important, such as just before a predicted rain.

Aerial planting onto freshly prepared seedbeds is another method used to plant alfalfa with good success, especially in fluffy seedbeds. Aerial applicators, experienced in planting alfalfa, can make an important difference between success and failure. With broadcast planting, two passes in a crossing pattern may be necessary for uniform coverage. Rolling the fields after aerial planting is advisable.

No-till or minimum-tillage drills can do a good job of placing alfalfa seed at the correct depth. When establishing alfalfa on steep slopes or otherwise erosive or shallow soils, this type of drill is best.

When it is impossible to prepare a firm seedbed due to excessively dry conditions, dusting-in the seed is an alternative. The bottom ends of the flexible seed tubes should be removed from the drill shanks and tied so that seed drops on the surface of the shallow furrow. A drag chain may be used to cover the seed with soil. Rainfall then firms the soil. A major risk of this establishment method is that it is dependent on receiving a soaking rain by early October.

Alfalfa plants are continually subjected to pest stresses. An effective integrated pest control program is essential for full stand establishment, productivity, and profitability of alfalfa. Integrated pest management should be comprehensive and targeted at the most important insect, disease, and weed problems.

Insects begin attacking alfalfa plants at emergence. Frequent scouting of new stands is essential for good insect control. Grasshoppers, armyworms, cutworms, and other general feeders can infest a new stand in a few days. Timely application of insecticides is the only reliable method of control. Spotted alfalfa aphids build up during the fall on seedling alfalfa. Blue alfalfa aphids are present nearly every spring. Using well-adapted, resistant varieties and good cultural practices that encourage rapid growth provide the best controls for aphid infestations.

Weeds in new alfalfa stands are a major concern. They can interfere with the planting operation and compete with seedlings for nutrients, water, and light. Weeds can reduce forage quality and yield of first-cut hay. In some cases weeds cause stand failures.

Diseases, such as damping off and root rots, are sometimes problems with alfalfa stand establishment. Fungicidal treatments, applied to seed or sprayed on seedlings, are effective for a short time and may make the difference between successful stand establishment and failure. Genetic resistance in conjunction with crop rotation, good land preparation practices, and good seedbed preparation are long-lasting control measures. Root rots are most commonly found in soils that are wet for prolonged periods; therefore, correcting drainage problems before planting is an excellent disease prevention measure.

See Chapter 2, "Pest and Pest Management," for detailed discussions of each group of pests.

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Alfalfa can be replanted in the same year in some situations but is not recommended because of:

Autotoxicity (alfalfa seedlings inhibited by alfalfa residues in the soil)
Depleted soil moisture
Soilborne insects and diseases from the previous alfalfa crop
Nutrient deficiency and pH problems
Drainage problems

Many studies indicate that alfalfa can be reestablished successfully following alfalfa. Most reports of problems with autotoxicity are from spring-planted field studies where top growth of alfalfa was incorporated into the soil and alfalfa replanted immediately. Assuming little foliage was plowed under due to a thin stand, the importance of autotoxicity is reduced greatly.

Under some circumstances good producers can have success with alfalfa following alfalfa immediately with special attention. 

In Oklahoma there are only a few good rotational crops for alfalfa. The best rotational crops following alfalfa are cereal crops and annual forage grasses. Small grains can benefit from nitrogen released after alfalfa is plowed. Corn and sorghum could also follow alfalfa in those areas where rainfall is adequate or where irrigation is available.

Yield improvement of cereal crops following alfalfa has long been recognized. Much of this is related to nitrogen (N) fixation by alfalfa. The amount of nitrogen plowed down is highly variable and depends on the time of the season and the amount of nitrogen-rich top growth at the time of tillage. About 25 percent of the incorporated nitrogen associated with plowing down alfalfa is recovered during the next crop year.

Herbicide residue problems following alfalfa:  There are crop planting restrictions following use of herbicides on crops grown in rotation with alfalfa. These restrictions are listed on the labels of herbicides and need to be followed to avoid injury to crops following herbicide applications. Some examples of replanting restrictions listed on herbicides used in alfalfa at the time of this writing follow. For updates on labels, one should check CDMS on the World Wide Web.

The crop preceding alfalfa is critical for alfalfa stand establishment. It should be an annual cool-season grass to allow sufficient time for preparation of a good seedbed. Harvesting a small grain crop in June usually allows adequate time for seedbed preparation for an early September alfalfa planting. Using soybean, peanut, or other legume species just before or just after alfalfa is usually avoided because they are ineffective in reducing buildup of disease organisms.

Herbicide residue problems preceding alfalfa: In Oklahoma rotational crop restrictions exist for alfalfa on many herbicides used on other crops (Table 3-2). The reason for these restrictions is that there may still be enough herbicide residue in the soil to injure subsequent crops. Damage (stunting) of newly-planted alfalfa is not uncommon in Oklahoma fields where persistent herbicides such as GLEAN and AMBER were used for weed control in wheat the previous spring.

This has been particularly evident after dry summers following herbicide application. To be safe, producers should always read and follow crop rotation restrictions on herbicide labels. This includes keeping accurate records of:

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The following topics are not necessarily part of normal alfalfa stand establishment in Oklahoma. However, they are critical to many individual producers as indicated by the number of times these questions are directed to extension and research staff.

Answer: Very thin first-year stands can sometimes be thickened. This refers to stands with large bare spots and areas with only 3 or 4 seedlings per sq. ft.

Thickening old (2 or more years old) thin stands is rarely successful. Attempts to plant alfalfa into old, thin stands usually result in few, if any, new seedlings becoming productive plants. Before reseeding a thin stand, reasons for the thin stand should be evaluated and corrected.

Seedlings cannot compete with mature plants for nutrients, water, and light. In addition, seedlings are sensitive to pests that build up in and on old plants in established stands. If an old stand has thinned to the point that it is not productive, the field should be rotated to another crop for several years before reestablishing alfalfa.

"Drowned-out" spots: There is a temptation to replant drowned-out spots. This is justified only if the reasons for the wet spots are corrected. After correcting drainage and preparing a good seedbed, alfalfa can be established successfully. Trying to fill in wet spots with new alfalfa without correcting the problem usually results in another stand failure.

Thin seedling stands: There is little danger of autotoxicity problems in thin stands less than a year old. If the reason for a thin stand from a fall-planted stand was poor seedbed preparation, late planting, or wash-out (blow-out), then overseeding into thin spots in early spring could thicken areas with fewer than five plants per square foot.  Likewise, thin spring-planted stands can be thickened up the following fall when there is almost no danger of autotoxicity. Again, the problem that caused the original poor stand must be corrected. Even after a few months, soils become hard and weeds encroach, normally resulting in poor seedbeds.

Answer: Only use companion crops that do not crowd out alfalfa. Planting a small grain with alfalfa during establishment is not usually recommended under Oklahoma conditions. In fact these crops and winter weeds should be controlled with herbicides, since they compete for moisture and light, resulting in reduced yield and quality of alfalfa. They may cause complete stand loss. On sandy soils, a thin stand of a grass such as German millet is a good way to protect alfalfa seedlings from wind-blown sand. German millet can be planted (at five pounds per acre) before alfalfa or with it. Planting other non-winter hardy crops, such as sorghum-sudangrass or spring oats, 3-4 feet apart in east-west rows, is another good option. Thin stands of summer weeds can also serve as a companion crop. Because these plants die in the winter, they are not competitive with alfalfa during the subsequent spring. Some producers have successfully planted turnips with fall-planted alfalfa and use the turnips for livestock grazing in the winter and spring.

Answer: It is considered very risky to attempt no-till establishment of alfalfa in Oklahoma. For this reason, little no-till is practiced. No-till requires even more long-range planning than conventional establishment. Land shaping for improved drainage must be done prior to establishing the previous crop. In addition, fertilizer and lime for the alfalfa crop should be applied and incorporated before the previous crop. Application of lime and phosphorous to the soil surface is not as effective; thus, more must be applied.

When planting alfalfa into existing vegetation, control of weeds and insects are also more difficult. More rain may be required for alfalfa emergence with no-till practices since the existing plants will be using water.

No-till planting of alfalfa into established sod is not usually successful. If alfalfa is planted into fescue or bermudagrass sod, bands of sod must be killed. The bands can be 6-8 inches wide and spaced every 20-40 inches. Plants can be killed with herbicides or certain minimum-tillage drills. Planting alfalfa into fescue or bermudagrass sod is also difficult because of problems related to insufficient water. When planting into sod in the fall, the soil may be dry because of water usage by the grass during summer. Interseeding alfalfa in the spring puts alfalfa seedlings at a disadvantage because of the strong competition with the established grass.

The best results with no-till alfalfa establishment have been into stubble of cool-season annual crops such as wheat. Summer weeds and volunteer wheat plants can be a major problem, and controlling them with herbicides may be excessively expensive. This is especially true with above-average summer rainfall. Alfalfa can also be interseeded into German millet stubble if the millet grows for only a few weeks and is harvested for hay just before planting alfalfa. The millet's fine stems do not interfere with most common alfalfa planters. The short growth period for millet does not dry the soil as much as other warm season crops. Millet regrows very little after cutting and offers little competition to alfalfa seedlings.

Answer: Effective nodules on alfalfa, generally pink to deep red on the inside, can fix several hundred pounds of nitrogen per acre each season. Assume a five-ton per acre yield of 20 percent protein hay. This amounts to a ton (or 2,000 pounds) of protein. Protein contains about 16 percent nitrogen. This means that the plants fixed about 320 pounds of nitrogen per acre. Higher yields or higher average protein concentration would obviously require more nitrogen fixation.