Chapter IV: Alfalfa (3)

Nearly all the seed now grown in the United States is produced by fields that have been sown in the usual way, and primarily to produce hay, but in some areas, especially where irrigation is practiced, it is sometimes grown mainly for seed. On the irrigated lands of the West it is customary to grow the first cutting of the season for hay and the second for seed. But in many instances the second cutting also is made into hay, and the seed is taken from the third cutting; even in the States east of the Mississippi, and also in Ontario and Quebec, seed is usually taken from the second cutting. But in Montana, Washington and Idaho, on the higher altitudes, seed is not unfrequently taken from the first cutting for the season, since, in the short season for growth of those uplands, seed from cuttings later than the first does not always mature so well. In a large majority of instances seed does not form so profusely from plants of the first cutting as from those of later growths. This is thought to arise, in part, at least, from the fact that bees, and it may be other insects, are then less active in searching for food, and because of this do not aid in the fertilization of the plants as they do later. Nor does seed of the first cutting ripen so evenly. An important justification is also found for taking seed from the later cuttings, in the fact that when a crop has produced seed, it grows less vigorously during the subsequent period of growth that same season. So pronounced is this habit of growth in alfalfa, that in many localities, if the first growth is allowed to produce seed, but little subsequent growth will be made again the same season. The second cutting, all things considered, is the most favorable to seed production, as, unless on irrigated lands, the third cutting is not usually possessed of that vigor necessary to induce abundant seeding in the plants.

The yields of seed are also much influenced by moisture. An excess of moisture is more unfavorable to the production of seed than a shortage in the same. Hence, in areas where the rainfall for the season is very abundant, but little seed will be produced. Where irrigation is practiced, the excessive application of water would have a similar effect, though less pronounced in degree; hence, the apportionment of the water to the prospective needs of the seed crop calls for careful adjustment. Where the first crop is grown for seed, where irrigation is practiced, in many instances no water is applied until after the seed crop has been harvested.

The seed is ready for being harvested when a majority of the seed-pods assume a dark brown tint. The pods of later formation will still possess a yellow tint, and some of them may still possess the green color. These do not produce seed nearly equal in quality to the pods which ripen earlier. To wait for all the later maturing pods to ripen before harvesting the crop would mean the loss of much of the best seed through shattering. Another test of maturity is made by shelling the pods in the hand. When the seed can be thus shelled in a majority of the pods in a single plant, it is ready for being harvested. Alfalfa seed shatters easily; hence, it is important to harvest the seed crop with promptness when it is ready, to handle it with due carefulness, and in some instances to refrain from handling during the hottest hours of sunshine.

The seed crop is sometimes cut with the mower and raked into winrows, and in some instances put up into cocks. When it is handled thus, the aim should be to do the work, as far as this may be practicable, in the early and late hours of the day, but not, of course, while much dew is on the crop. Sometimes the seed is drawn from the winrows to the thresher; in other instances from the cocks, and in yet other instances it is stacked before being threshed, a work that calls for the exercise of much care in the storing of the crop, lest the seed should be injured by heating in the stack. This method of harvesting is usually attended with much loss of seed.

There is probably no better way of harvesting alfalfa than to cut it with the self-rake reaper or the binder. The loose sheaves dry quickly, and when lifted, the aim is to carry them directly to the thresher. Less seed, it is considered, will be lost in this way than by the other mode of harvesting given above, and the work is more expeditiously done. But owing to the difficulty in securing a thresher to thresh the seed, it is sometimes found necessary to stack the crop, but in areas where irrigation is practiced such stacking is seldom necessary.

The seed is frequently threshed with the ordinary threshing machine, but in many instances it is also threshed with a clover huller. The huller does the work less quickly, but probably, on the whole, more perfectly. Threshing machines, with or even without certain adjustments in the arrangement of the teeth in the cylinder and concave, and with extra screens, are now doing the work with much despatch, and with a fair measure of satisfaction. But the opinion is held by competent judges that a machine that would more completely combine the qualities of the thresher and the huller would be still more satisfactory. It is easily possible to have the crop too dry to thresh in the best condition, and care should be taken to regulate the feed in threshing so that the alfalfa will not enter the cylinder in bunches. More than 200 bushels of seed have been threshed in a day from crops which yielded abundantly. The seed should be carefully winnowed before putting it on the market. The seed crops, as would naturally be expected, vary much; crops are harvested which run all the way from 1 to 20 bushels per acre. From irrigated lands the yields are, of course, much more uniform than from unirrigated lands, since in the former the supply of moisture may be controlled. Fair to good average yields on these may be stated at from 4 to 6 bushels, good yields at from 6 to 8 bushels per acre, and specially good yields at from 10 to 12 bushels. The bushel weighs 60 pounds. Growing alfalfa seed under irrigation has frequently proved very profitable. The seed grown in such areas is larger and more attractive to the eye than that ordinarily grown in the absence of irrigation, and because of this many are lured into sowing it on unirrigated land when the former would better serve their purpose. The seed is frequently adulterated with that of yellow clover (_Medicago lupulina_), which resembles it closely, but this is more likely to be true of imported than of American grown seed.

=Renewing.=--Alfalfa may be renewed and also renovated where the stand secured at the first has been insufficient, where it may have been injured from various causes, where it is being crowded with weeds, and even with useful grasses, and where the land requires enriching.

The stand of alfalfa secured is sometimes thin and uneven. This may arise from such causes as sowing too little seed; whether over-dry or through the crowding of the young plants. When this happens, in many situations it is quite practicable to thicken the stand by disking the ground more or less, adding fresh seed, according to the need of the crop, and then covering the seed thus added with the harrow. Such renovation would be comparatively easy on clean land, were it not for fact that the alfalfa plants already rooted overshadow the young plants, always to their injury, and sometimes to their total destruction. The spring will probably be the best season to attempt such renovation, but there may be instances where the winters are not severe, in which autumn seeding will succeed as well or better than spring seeding. Because of the uncertainty of the results of such renovation, the aim should be so to prepare the land and sow the seed that a good, thick stand will be secured at the first.

Should the alfalfa fields be spotted, because in places the nurse crop lodged and smothered the plants, or because excessive moisture destroyed them on the lower portions of the field in an abnormally wet season, the renewing process is simple indeed. It consists in disking those parts so thoroughly as to destroy all vegetation that may have become rooted on them, and sowing seed in the usual way without a nurse crop. But should the low places be such as to hold an excess of water at any time of the year under normal conditions for days in succession, even though it should not rise to the surface, the attempts to make alfalfa grow successfully on these will prove abortive.

When weeds and grasses crowd the crop, the plan of disking the fields to destroy these is becoming quite common, especially in the West. The work is usually done in the early spring. In doing it, disk harrows are driven over the field, usually two ways, the second disking being done at right angles to the first. The disks are set at that angle which will do the least injury to the plants, and that will at the same time do the work effectively. This can only be determined by actual test in each instance. Some of the crowns of the plants will be split open by the disk, which some authorities claim is an advantage in that it tends to an increase in the number of the stems produced, an opinion which is by no means held in common at the present time, and yet there are localities where it has certainly proved advantageous. Occasionally, a plant will be cut off. There can be no doubt, however, that such disking, when necessary, does tend to clean the land and also to strengthen growth in the alfalfa crop, on the principle that cultivation which does not seriously disturb growing plants is always helpful to them. The frequency of such diskings will depend on the needs of the crop. Some advocate disking every spring, some every other spring, and some not at all. That plan which disks the ground only when it is necessary to keep the weeds at bay would seem to be the most sensible. This would mean that sometimes, as where crab grass has a firm hold, disking may be necessary at least for a time every spring. In other instances it would be necessary only every second or third season, and in yet other instances not at all. However, some growers in dry areas advocate disking frequently, as, for instance, after some of the cuttings of the hay, and with a view to retain moisture. It is at least questionable, however, if disking so frequently would not soon tend to thin the plants too much, to say nothing of the labor while the work is being done.

The idea of stirring the surface soil in alfalfa fields is by no means new. In England the plan prevailed to some extent years ago of harrowing the fields in the autumn with heavy harrows until, when the process was completed, they would take on the appearance of the bare fallow for a time. In the Eastern States and in some parts of Canada the harrow is used instead of the disk, but usually the latter will do the work more effectively and with less cost. Frequently, when the disk has been used on alfalfa, it may also be advantageous to run a light harrow over the ground to smoothen the surface.

With a view to renovate the crop and increase the yields, in some sections, as in the Atlantic States, it has been recommended to top-dress alfalfa fields with farmyard manure every autumn. This, no doubt, would prove very effective, but it would also be very expensive, unless in the neighborhood of large cities. It would be impracticable without neglecting the needs of the other crops of the farm. In the mountain areas of the West, it has been found that the cost of fertilizing with farmyard manure is in the meantime greater than the increased production in the alfalfa is worth, but it may not be always thus, even on these rich lands. Some Eastern growers also apply more or less gypsum. This is generally sown over the fields after the crop has begun to grow in the spring.

Renovating alfalfa fields is much more easily and effectively done, as would naturally be expected, in areas where conditions are highly favorable to its growth than where these are only moderately favorable. In some of the mountain valleys instances have occurred in which alfalfa fields have been plowed and sown with oats, with a result, first that a good crop of oats was reaped, and second, that fairly good crops of alfalfa were harvested the following season without re-sowing the field.

=Sources of Injury to Alfalfa.=--Chief among the sources of injury to alfalfa, after the plants have become established, are frost in saturated ground, ice, floods, grasshoppers, gophers, dodder, and pasturing by live stock in the late autumn or winter. When it happens that two or three of these act in conjunction, the injury following is just so much more rapid and complete. As has been intimated, where water is excessive, in a climate which in winter or spring is characterized by alternations of freezing and thawing, the plants will either have the roots snapped asunder, or they will be gradually raised out of the ground. This will only happen in soil with a subsoil more retentive than is compatible with well-doing of the highest order in the plants. The danger from this source is greatest during the first winter after sowing the plants, as then the roots are not really established. The only remedy for such a contingency is the draining of the land.

Some reference has also been made to injury done through ice, where it collects in low places in land. The destructiveness of the ice depends on its thickness and its nearness to the ground. When it rests upon the ground for any considerable time the plants die. If, however, water intervenes, the plants may live when the submergence is for a limited time. One instance is on record in Onondaga County in New York State, in which alfalfa survived submergence for a considerable period under a thin sheet of water covered by three inches of ice, but when growth came it was for a time less vigorous than normal.

Floods in warm weather are greatly injurious to alfalfa. The extent of the injury done increases with increase of depth in the waters of submergence, increase in stagnation in the waters, and increase in the duration of the period of overflow. Stagnant water sooner loses its dissolved nitrogen; hence, the plants cannot breathe normally. The harm done, therefore, by floods in each case can only be known by waiting to see the results. These summer floods always harm the crops temporarily, and in many instances kill them outright. Occasional periods of overflow should not prevent the sowing of alfalfa on such lands, since on these it is usually not difficult to start a new crop, but the seed should not be sown on such lands when overflow occurs at such a season. When it occurs in cool weather and quickly subsides, it may be possible to grow paying crops of alfalfa.

In some areas grasshoppers are a real scourge in alfalfa fields. Because of the shade provided by the ground and the influence which this exerts in softening it, they are encouraged to deposit their eggs and remain so as to prove a source of trouble the following year. It has been found that through disking of the land both ways after sharp frosts have come is greatly effective in destroying the grasshopper eggs deposited in the soil. They are thus exposed to the action of the subsequent frosts and so perish. The disking has also tended to stimulate growth in the crop the following year. The eggs will not, of course, be all destroyed by such disking, but so large a percentage will, that the crop should be practically protected from serious injury, unless when grasshoppers come from elsewhere.

It would seem correct to say that gophers do more injury to alfalfa fields in certain areas of the West than comes to them from all other sources combined. They not only destroy the plants by feeding upon them, but they fill the soil with mounds, which greatly interfere with the harvesting of the crops. They are destroyed by giving them poisoned food, trapping, shooting, and suffocating through the use of bisulphide of carbon. Poison is frequently administered by soaking grain in strychnine or dropping it on pieces of potato and putting the same in or near the burrows. Bisulphide of carbon is put upon a rag or other substance, which is put into the burrow and the opening closed.

Dodder is a parasitical plant introduced, probably, in seed from Europe, which feeds upon alfalfa plants, to their destruction. The seeds of alfalfa sometimes become so impregnated with the seeds of dodder that the latter will grow where the seed is sown, thus introducing it to new centers. The dodder starts in the soil and soon throws up its golden-colored thread-like stems, which reach out and fasten on the alfalfa plants that grow sufficiently near. The dodder then loses its hold upon the soil and gets its food entirely from the alfalfa plants, which it ultimately destroys. But since the seeds of the dodder remain at least for a time in the soil, and the adjacent soil becomes infected with them, the circles in which the dodder feeds continually widen. In certain parts of New York State some fields have become so seriously affected as to lead to investigations conducted through officials from the State experiment station. Pending these investigations, the exercise of great care in the purchase of seed and the immediate plowing of the infested areas are recommended.

Some reference has already been made to injurious results from pasturing close in the autumn or winter, except in the most favored alfalfa regions. In addition to what has been already said, the wisdom of not grazing alfalfa the first year is here emphasized, and also the mistake of grazing at any time when the ground is frozen, at least in areas east of and, generally speaking, adjacent to the Mississippi River.

=Alfalfa as a Fertilizer.=--Alfalfa is not considered equal to medium red clover as a direct means of fertilizing and otherwise improving the land on which it grows. This does not arise from less inherent power on the part of alfalfa to draw nitrogen from the air and deposit it in the soil, but rather from the fact that clover establishes itself more quickly, and is much more frequently grown in the rotation. Several crops of medium red clover can be grown in short rotations, each one being a source of much benefit to the crops that follow, while one crop of alfalfa occupies the land. But when the alfalfa is all fed upon the farm on which it grew, where the plants grow freely, it then becomes a source of fertilization without a rival, probably, among plants grown upon the farm.

The fertility thus furnished does not consist so much in the plant food deposited in the soil directly as in that furnished in the successive crops that are grown and fed every year. In Farmers' Bulletin No. 133, published by the United States Department of Agriculture, it is stated that the Wyoming Experiment Station found 44 pounds of nitrogen, 8.27 pounds of phosphoric acid, and 50.95 pounds of potash in one ton of alfalfa. This would mean that in the yield of alfalfa hay from a given area, estimated at four tons per acre for the season, alfalfa would furnish 176 pounds of nitrogen, 33.08 pounds of phosphoric acid, and 203.8 pounds of potash. If this alfalfa were fed upon the farm, it would not only prove a cheap source of protein for feeding, but it would furnish fertility, as stated above, without seriously diminishing the supply of the same in the surface soil, since much of the fertilizing material produced would come from the air and subsoil. The manure thus made, if carefully saved and applied, would thus add materially to the fertility of the land. If, however, the alfalfa were sold, the mineral matter drawn from the cultivable area of the soil and from the subsoil lying under it would be reduced to the extent of the draft made upon these in growing the alfalfa.

The direct influence of alfalfa upon the fertility of the land on which it grows is shown in the greatly increased production in the crops which follow alfalfa. This increase is not only marked, but it is frequently discernible for several successive years. But as has been intimated, the benefit that would otherwise accrue from growing alfalfa as a direct means of fertilizing the land is much circumscribed by the long term of years for which it is usually grown.

The mechanical effects of alfalfa upon the land are beneficent. It improves the tilth by means of the shade furnished, and the extent to which the roots fill the soil. These in their decay further influence favorably that friability which is so desirable in soils that are cultivated, and as previously stated, the long, deep roots in their decay exercise a salutary influence on drainage.

The work of breaking alfalfa fields is frequently laborious, owing to the number and size of the roots. If, however, a plow is used, the share of which has a serrated edge, the roots will be cut or broken off more easily and more effectively.