Alfalfa thrives on limed soil, as shown in the upper photograph. The alfalfa shown in the lower photograph was on the same kind of land, in the same field, but unlimed. This field is in the Central Bluegrass area of Kentucky.
GROWING ALFALFA
in KENTUCKY
ALFALFA undoubtedly is the most dependable hay crop for Kentucky. With proper care it lasts several years, producing 3 to 5 crops annually, depending .upon the length of the growing season. At least one good crop a year is therefore almost certain, even in years when drouth is severe or rainy weather makes curing difficult. Dependability, high acre-yield, high nutritive value, and excellent palatability should give alfalfa a place on thousands of Kentucky farms where it is not now grown. Of the meadow crops suited to Kentucky it is not the easiest to grow, tho perhaps one of the great advantages of growing alfalfa is that often the soil must be improved in order to grow it.
Alfalfa can be grown successfully in any part of the state where the soil has good underdrainage. Too much free water in the upper 2 feet of soil is a frequent cause of partial or complete failure of alfalfa stands. If the soil is fertile and neutral or only very slightly acid it will produce good crops of alfalfa without further soil treatment. Soils that contain limestone fragments, such as the hill lands of northern Kentucky, or those on slopes below marl outcrops, as in the areas of red limestone soil just outside the Western Coal Fields, are usually suitable for alfalfa without liming. Most well-drained bottomland also, produces a good yield of alfalfa without soil treatment. In most other areas of the state the soil must be properly treated before it will produce a good yield of alfalfa.
Lime.— Liming the soil is the treatment most generally needed for alfalfa. As a rule, 3 tons of ground limestone per acre is the amount most satisfactory to apply. It should be applied at least 2 months before seeding, so as to give time for some of the limestone to dissolve. Marl or burned lime may be used instead of limestone, but the amount to be used should be determined by the neutralizing value of the material. On the average ½ ton of fresh, burned lime or ¾ ton of water-slaked lime is about equal to 1 ton of limestone in correcting soil acidity. The neutralizing value of marl should be ascertained by chemical analysis.
The value of liming for alfalfa has been demonstrated time and again on Kentucky farms. At the Experiment Station farm at Lexington the use of fertilizers alone gave little or no increase in yield of alfalfa, but 2 tons of ground limestone per acre increased the yield per acre per year from 3,239 pounds to 5,604 pounds, and 4 tons increased it to 6,443 pounds. When 6 tons of limestone were used per acre the yield was only 6,270 pounds per acre.
On land that needs phosphorus or potassium, lime also usually is needed. If the land has been limed within the past few years, however, it may need no further liming to get a good stand of alfalfa.
Phosphorus.— Outside the Bluegrass region most soils of Kentucky need phosphorus treatments in order to grow alfalfa well. Even in the Bluegrass region some soils need more phosphorus for continued good yields. The amount needed differs according to the soil, but liberal applications are advisable because of the large amounts of phosphorus removed by alfalfa crops. The hay removed annually from an acre of a good.stand of alfalfa contains, on the average, as much phosphorus as 100 to 200 pounds of 20-percent superphosphate. On soil very deficient in phosphorus the application should therefore be at least 100 pounds of 20-percent superphosphate per acre, or its equivalent in other phosphate fertilizers, for every year the crop is to be on the land. The best time to apply the fertilizer is at seeding time. If all of it is not put on then, part should be applied and the remainder broadcast later, after a hay crop has been removed.
Potassium.— Most Kentucky soils are well enough supplied with potassium to produce large yields of alfalfa. Some fields where alfalfa has been grown for a number of years may, however, be low in potassium, low enough to cut down the yield. Alfalfa is a very heavy feeder on potassium, 3 tons of alfalfa hay containing, on the average, 100 to 125 pounds of potassium.
Before applying potash fertilizer to a whole field, make a preliminary test by putting it on 3 or 4 small plots scattered over the field, at the rate of 200 or 300 pounds of muriate or sulfate of potash per acre, top-dressed. If the treatment definitely improves the alfalfa on the small plots, the whole field should then be top-dressed.
Boron.— From field tests made during the summer of 1942, it appears that some soils of Kentucky contain too little boron for good crops of alfalfa2. Where there is not enough boron the leaves are likely to be yellow or yellowish purple. The plants may be somewhat stunted and may produce little bloom. These conditions are most likely to occur during dry weather. Fields of this description should not be treated with boron, however, before making a field test, because leafhopper attacks and potash deficiency produce symptoms somewhat similar to those of boron deficiency. To make a field test, treat a small plot with a potash fertilizer (as already suggested) and another beside it with borax, the most practical carrier of boron. Perhaps 20 pounds of borax per acre is sufficient, and over 50 pounds may be harmful3.
As it is not easy to distribute a small amount of borax evenly, it should be mixed with some other material, such as dry sand or soil, to increase the bulk. Doubtless borax may be applied satisfactorily immediately after a cutting of alfalfa has been removed, but it is likely that there is no better time than in early spring before new growth begins.
Preparing for alfalfa by growing sweet clover.— Alfalfa may be grown on run-down land by growing a crop of sweet clover ahead of it and turning it under. Sweet clover grows much better on run- down land than alfalfa and leaves the soil inoculated for alfalfa. The sweet clover seed should be inoculated when sown, and the soil should be limed and phosphated as described in the preceding paragraphs.
The varieties of alfalfa grown in the United States fall into two major groups—common and variegated. Common alfalfa may be considered a variety with many strains known by state names, such as Kansas Common, Idaho Common, some of which are certified by seed or crop improvement associations. Turkistan, Hardistan and Kaw also apparently are common alfalfas. Variegated alfalfas include Grimm, Cossack, Baltic, Hardigan and Ladak varieties, and these, in turn, consist of strains designated by state names, such as North Dakota Grimm, Montana Cossack, etc.
The Hardigan variety was superior to all others in tests conducted by the Kentucky Agricultural Experiment Station. Varieties from the southwestern part of the United States are least well adapted to Kentucky, tho seed from central and northern California has not been tested here. Turkistan, Hardistan, Kaw, and Ladak varieties are not well adapted. Yields produced by other varieties differed greatly but until more information is obtained regarding the adaptability of certified strains, no definite recommendations regarding them can be made. In general, however, the varieties best adapted to Kentucky are from Canada and the region of the United States north of the latitude of the southern boundary of Kansas. Northern Oklahoma seed seems as well adapted as some Kansas Common, and may be considered generally satisfactory for Kentucky. Differences in winter hardiness and resistance to diseases and insects account for most of the differences in adaptation.
Alfalfa seed can now be bought on the market with assurance as to its origin, and therefore as to its probable suitability for use in Kentucky. The Federal Seed Act requires that each container of domestic alfalfa seed in interstate commerce be labeled to show its origin, if known, and that 10 percent or more of the seed in each container of imported alfalfa seed unadapted to general agricultural use in the United States be stained red or orange red. Imported alfalfa seed, except that from Canada, is therefore so marked and is easily distinguishable from domestic seed. Furthermore, each container of seed must be labeled in conformity with the provisions of the Kentucky Seed Law, and of the Federal Seed Law if its contents are shipped interstate, to show percentages of germination and of other seeds and materials present that affect the value of the seed for seeding.
Certification by seed and crop improvement associations also provides reliable information most helpful in purchasing adapted seed. These associations specify the kind of seed, its variety name, percent germination, purity, and kinds of weed seed present. This information is placed on a tag which is attached to the bag of seed offered for sale.
For seeding alfalfa on soil that does not contain the nodule-producing organism of alfalfa, the seed should by all means be inoculated. Seedlings without root nodules may become yellow, weak, and generally so unthrifty that they cannot successfully compete with weeds or resist diseases. The stands rapidly thin out, tho some of the remaining plants may in some way become inoculated and survive. By that time the stand is so thin and weedy that it is of little or no value. Therefore, all seed should be inoculated unless the field in which it is to be sown has recently produced a good crop of alfalfa or sweet clover. Even then inoculation may be beneficial.
One good way to do the inoculating is to work fine soil from an old alfalfa or sweet-clover field into the seedbed at the rate of about 200 pounds to the acre shortly before or at the time of seeding. Another method is to sprinkle partly dried, pulverized soil from about the roots of well-inoculated alfalfa or sweet-clover plants over the slightly moistened alfalfa seed, and mix until soil sticks to all the seed. The common practice, however, is to inoculate with commercial cultures, because of their convenience and general dependability. These cultures should be used strictly according to directions printed on the container.
Obviously, a uniform stand of good seedlings is essential for a satisfactory alfalfa meadow. Six or 7 pounds of good seed to the acre, if sown uniformly on a perfect seedbed when weather is ideal, will produce a good stand, but seldom are all these conditions right to produce such a result. Therefore it is safer to sow 10 to 12 pounds to the acre. Higher rates are often used, but over 15 pounds to the acre is more than necessary if conditions are good enough to justify seeding at all.
In Kentucky, alfalfa may be seeded in August, February, or March. August seedings should be made between the 5th and 20th in northern Kentucky; between August 15 and September 1 in the southern part of the state; and at intervening dates in the middle part. Stands from somewhat later seedings are often successful, depending upon the favorableness of fall and winter weather. A few farmers have had good results from September seedings made with small grain. Spring seeding may be made between the middle of February and the first of May, but the best time is usually from about March 10 to April 10 in northern Kentucky, and from March 1 to April 1 in southern Kentucky.
About 60 percent of Kentucky's alfalfa acreage is seeded in the spring, in a nurse crop, probably because the work is done more cheaply and conveniently than in August. Furthermore, moisture conditions usually are more favorable in the spring than in August, so that good stands are generally easier to obtain in the spring if care is taken to provide a light covering for the spring-sown seed. Spring seedings must, however, compete with a nurse crop; and unless the soil already contains the nodule-forming bacteria the conditions for inoculation seem to be somewhat less favorable than in August.
August seeding, if properly done, has the advantage of providing a uniform, weed-free seedbed, and apparently of being especially favorable for inoculation. It has the disadvantage of leaving the soil largely unprotected against erosion during the following winter—a serious objection on all but level land. There is little choice between summer and spring seedings in susceptibility to disease.
Proper condition of the seedbed is very important. It should be firm, yet the surface should be in condition to provide a shallow covering of the seed. These conditions are almost always provided in the prepared seedbed, especially if a cultipacker can be used before and after seeding on dry soil, but they are too often lacking when seed is sown in a winter nurse crop. Seed sown on a well-honey- combed soil should be satisfactorily covered, but there is danger that the seedlings may be injured or killed by late freezes. Seeding late enough to avoid this danger necessitates a light stirring of the soil to provide covering for the seed. This may be done at the time the seed is sown if a clover-seed drill or a grain drill with a grass-seed attachment is used. If these are not available, a disk, drag harrow, or rotary hoe may be used. A cultipacker is satisfactory also if the surface soil is dry. Excellent stands are usually obtained by seeding on a nurse crop which .is being pastured, especially with sheep. The tramping of the soil produces the desired seedbed preparation. A heavy nurse crop is a disadvantage to alfalfa seedlings, consequently it should be pastured, if possible, to remove part of it; or it should be clipped before the plants joint. On the average a nurse crop should not be pastured or clipped after about April 1 if it is to be cut for grain.
Tho the clover-seed drill and the grain drill with the grass-seeding attachment are very effective machines for proper seeding, they are not always available. Several kinds of hand-operated seeders are used. The wheelbarrow seeder does rapid and uniform sowing on level to gently sloping land. Horn and cyclone seeders are most generally used thruout the state because they are inexpensive and may be used satisfactorily under most conditions if one does not try to sow in too-wide strips. Hand broadcasting is not recommended except for one skilled at it and even then it is usually advisable to sow half the seed in one direction and half at a right angle to the first.
Perhaps more problems of management arise with alfalfa in its first year than in all the rest of its life. If the nurse crop is heavy, should it be allowed to mature or should it be pastured closely or cut for hay? Not uncommonly, weeds become rather abundant; shall the field be clipped? Frequently the leaves become yellowish and the plants unthrifty in appearance; is it better to mow the crop or let it alone? The crop may make a large growth; shall it be cut for hay? If so, when? There are other questions which cause much concern. Unfortunately, no unqualified answer can be given for each situation. The main thing in deciding these questions is to keep in mind that generally the plants should have some good leaves on them at all times during the first year, and that they should make a good, undisturbed growth during the six weeks preceding the first heavy frost in the fall. Sometimes the stand may be moderately grazed; sometimes it should be c]ipped, especially if weeds are smothering the crop. However, the time to clip depends on the nature of the weeds. Sometimes weeds are killed by clipping; sometimes when clipped they recover more vigorously and quickly than the alfalfa. For example, ragweed belongs to the former type; crabgrass, during midsummer, usually to the latter. If ragweeds are clipped after they are large enough seriously to smother alfalfa, they usually will not make much recovery. Crabgrass, on the other hand, if cut during July and early August of any but a dry season, recovers quickly and soon produces a heavier growth than it would have produced had it not been cut, covering the new shoots of alfalfa. If clipped after it begins to mature, about August 25, it makes relatively little new growth, and the alfalfa shoots may have a chance to grow thru it. In managing the alfalfa field during its first year of seeding, make decisions with all these factors in mind.
Alfalfa should be cut for hay while the leaves are green and the stems still fine enough to make high-quality hay, but after the plants have matured enough to store food reserves in the roots to bring on a good crop for the next cutting. Some farmers determine when to cut by the stage of blooming or the length of the new shoots, but a more reliable practice is to cut according to the date. Make the first cutting about May 20 in southern Kentucky, and June 1 in northern Kentucky, with later cuttings at about 6-week periods thereafter. The last cutting should not be made later than about 6 weeks before the normal time of first killing frost. Alfalfa may be cut after it has been heavily frosted without injury to the stand; in fact, the next year’s crop sometimes is of better quality following late fall cutting.
The highest grades of alfalfa hay, according to federal standards, are green, leafy, practically free of weeds and foreign material, and with no objectionable odor. To make such hay, the crop must not only be essentially weed-free and cut before it is mature, but also it must be cured in such manner that it retains most of its leaves and color. It is usually impossible in Kentucky to cure alfalfa hay perfectly in these respects. The hay will cure rapidly in the swath, but it is usually much bleached before it is cured. Curing wholly in the windrow or cock, so that most of the green color is kept, is uncertain because of the risk of rain before curing is completed. Usually, wilting the hay well in the swath and completing the curing in small windrows produces a high-grade hay in a reasonable time. In rainy weather (a serious problem, especially with the first cutting of alfalfa), it may be necessary to cure altogether in the swath or largely in the swath and finish in cocks covered with hay caps. Where considerable tobacco-barn space is available, the partly cured hay can be spread in thin layers between the tiers to finish curing. Tho the first cutting each year commonly may be poorly cured because of unfavorable weather, the second and third cuttings can usually be cured satisfactorily. The two cuttings will supply the farm needs for highest quality hay; the first cutting, if poorly cured, meets less exacting roughage requirements.
Objectionable odor in hay may come from heating or molding in the mow, stack, or bale, or from foreign material or weeds that were in the field. Again, it may be caused by the surroundings under which the hay is stored. It is important, therefore, that hay not only be well cured in the field, but also that it be stored in a dry place where there are no objectionable odors, or in a properly built stack.
An increasing amount of alfalfa is being ensiled in Kentucky—for one reason, because of its outstanding feed value; and for another, because the loss from frequent rains at hay-curing time can be avoided by putting up the alfalfa as silage rather than as hay. For directions for making and feeding alfalfa silage, see Kentucky Extension Circular 360, “Grass Silage.”
Alfalfa seldom produces a good seed crop in Kentucky, though yields as high as 6 bushels an acre have been reported. Sometimes the plants produce but little bloom; at other times the blossoms fall too soon; occasionally the pods even though abundant are poorly filled. By watching the crop carefully as it matures, one can conclude whether it will be worth leaving for seed. Generally speaking, a good seed crop may be expected only if the weather is dry and the humidity is low while the alfalfa is in bloom. Sometimes, however, little or no seed is produced in Kentucky under these conditions; and occasionally good seed-setting occurs during periods of moderate rain.
On the whole, seed crops are produced often enough, perhaps, to enable a farmer to save enough seed for his own needs, provided he stores it from year to year in a cool, dry place. This practice is to be recommended especially to the farmer who has a field of alfalfa that has maintained an excellent stand and produced high yields for at least 5 or 6 years. Such alfalfa is likely to be very well adapted to his conditions, and it will become better adapted from seeding to seeding.
Alfalfa should be harvested for seed when two-thirds or more of the seed pods are brown or dark. Generally the crop in Kentucky will be most easily harvested with a mower and hay rake, except where a clover-seed buncher or a windrowing attachment to the mower is available for collecting the crop as cut. A self-rake reaper is an excellent implement for cutting the crop. If the crop is harvested with a grain binder and cured in small shocks, the sheaves should be small and rather loosely tied.
Usually alfalfa cut for seed in Kentucky must be dried before it can be cocked, stacked, or threshed; but it should be handled as little and as gently as possible to avoid shattering the seed. If the crop is so dry when ready to harvest that it would shatter badly it should be cut and handled early in the morning while slightly damp.
If dry, alfalfa is easily threshed, and the job may be done with a clover-seed huller, a threshing machine equipped with screens of suitable size, or with a combine harvester. Occasionally a crop may be mature and dry enough to combine while standing, but seed so harvested must usually be further dried to prevent its heating.
Either the second or third crop may be saved for seed, though late August and September seem best for seed setting and maturing. If the first and second crops are cut early rather than late, the third crop will mature during September. If new stem growth develops while the seed is maturing, avoid, if possible, cutting it in harvesting the seed.
Broadcasting fertilizers on old alfalfa fields which still have good stands is likely to be profitable. At the Experiment Substation at Princeton, for example, plots in 4-year-old and 5-year-old alfalfa fields which had received 400 pounds of 16-percent superphosphate per acre when the alfalfa was sown, were top-dressed with an additional 500 pounds per acre in the spring of 1931. The average annual yields per acre for 1931-1933 were 5,004 pounds of hay from that part of fields that were not top-dressed in 1931; and 7,164 pounds from the plots that were top-dressed. Plots that were top-dressed with muriate of potash at the rate of 200 pounds per acre together with 500 pounds of superphosphate produced an average of 7,370 pounds of hay per acre.
To find out whether top-dressing is needed on your field, apply a top-dressing on several small plots in different parts of the field. If the growth of alfalfa on those plots is definitely better than on surrounding parts of the field, then it will probably pay to top-dress the whole field.
When the soil is dry, harrowing alfalfa immediately after a crop is cut is usually effective in controlling shallow-rooted weeds that are present, such as crabgrass. If the soil is moist, however, little benefit will follow such cultivation.
A stand of alfalfa lives for many years on soil to which it is adapted, and the crop can therefore be grown under more or less continuous culture. It is a good crop, however, for relatively short rotations on land to which it is suited. Rotations such as corn, wheat, and two years of alfalfa are satisfactory in Kentucky. However, a longer rotation is preferable in most parts of the state, especially if grass is sown with the alfalfa. In this case the alfalfa mixture is used for hay for a few years, and then for permanent pasture until the field is returned to a cultivated crop. In general, a pure stand of alfalfa should not be kept for hay more than 4 or 5 years; otherwise the soil may become so depleted in available mineral plant food that it will not produce subsequent crops so well as it would had the alfalfa occupied the land a shorter time.
An alfalfa-grass mixture is so superior to alfalfa alone in Kentucky that alfalfa ought never be sown by itself, though perhaps there is no serious objection to it on level land. The outstanding advantage of the mixture is its distinct superiority over alfalfa alone in preventing erosion. Other advantages are better control of weeds, less danger of bloat when grazed, larger yield of hay after the second year, and generally better balance of nutrients in the hay and pasture.
There are few valid objections to the alfalfa-grass mixture. The mixed hay which is always produced from the first cutting brings a somewhat lower price on the market than alfalfa alone. The second and third crops, also, may contain small amounts of grass, but that cannot be considered a real disadvantage because, had there been no grass there probably would have been weeds. Farmers who wish to strip bluegrass seed where alfalfa and Kentucky bluegrass have been sown together are hindered by tall alfalfa in the bluegrass. The shoots of alfalfa can be kept down out of the way, however, by pasturing the mixture with sheep during the spring.
All grasses commonly used in Kentucky are satisfactory for sowing with alfalfa. Until more is known of the suitability of less well known grasses, they should not be largely used with alfalfa in this state. By sowing small acreages of them with alfalfa, farmers can become acquainted with their possibilities.
Though a pure stand of alfalfa is highly productive, very palatable, and nutritious pasturage, the alfalfa plant, strictly speaking, does not have the right habit of growth for a pasture plant, and alfalfa pasture therefore usually becomes weedy soon. A grass and alfalfa mixture, the two seeded together, produces better pasture than alfalfa alone.
Only one kind of insect, the potato leaf hopper, causes any appreciable damage to alfalfa in Kentucky—and that only occasionally. Ordinarily, therefore, farmers need pay no attention to insects on their alfalfa. However, should leaf hopper damage occur rather frequently on a given farm, it will probably pay the farmer to take steps to control the hoppers. The damage is done mainly to the second cutting, and the most noticeable feature of it is a yellowing of the leaves, or of the whole plant if the hoppers are especially numerous. The only practical method of control is to make the first cutting at such time that the eggs of the hoppers will be taken off and killed in curing of the hay. That will be later than is recommended (page 11) for cutting for best-quality hay; but when the hoppers are bad it will pay to sacrifice some quality of the first cutting in order to keep down injury to the second. The time for the first cutting, to control hoppers, is not earlier than June 5 in southern Kentucky; and not earlier than June 15 in northern Kentucky. That will catch most of the eggs most years. Even so, there will be some yellowing of the second crop; but by making the second cutting late in July the eggs for the next brood will be caught and there will be very few insects on the third crop.
At each cutting the whole field should be cut within a day or two from the time the cutting is started. If the field is not finished until new growth has started on the earlier-cut part, the hoppers from the late-cut part may attack the new growth and injure the plants severely.
Potato leaf hoppers are slender, pale-green insects about 14 inch long. When full-grown they are active and fly if disturbed; the young are wingless, and when disturbed they jump or run with a sidewise movement across the leaf. Young hoppers live chiefly on the underside of the leaves. Both the young and old have beaks for piercing the plants and sucking the juices, thereby causing yellowing of the leaves and sometimes of the whole plant. Where the hoppers are numerous, young stands of alfalfa may be destroyed by them. Adult hoppers collect on alfalfa about the first of June, and immediately begin laying eggs.
Alfalfa in Kentucky is generally affected by one or more diseases that gradually reduce the stand until it becomes unprofitable.
Where crown rot has become established, some rotting of crowns occurs each year in older stands, and fall-sown stands frequently are destroyed in late winter and spring. Spring-sown stands, on the other hand, are relatively free from crown rot.
Black stem is another common disease that generally reduces both the yield and the quality of the first cutting each year. It blackens the stems of the spring crop, kills new shoots that come from buds above the ground, and when particularly severe destroys the plants and rapidly reduces the stand. As the organism that causes the disease lives over winter on the dead stems of the previous year, the disease can be partly controlled by winter and spring grazing or by mowing and raking the field in late winter.
Another disease that destroys spring-sown seedlings in nurse crops, and that is especially bad in wet seasons, is “damping off.” It is caused by a fungus that works at the surface of the ground and thrives in humid atmosphere. Thin seeding of the nurse crop and heavy grazing of it may help to control this disease.
Alfalfa “yellows” is a yellowing of the leaves or of the leaves and stems of alfalfa. It commonly refers to the condition produced by attacks of the potato leaf hopper (see page 17), but there are at least two other kinds of yellowing and all three appear much alike. One of these causes is boron deficiency in the soil (page 5) and another is leaf spot or spots caused by disease or by potash deficiency.