A light top-dressing of manure after sowing, or, in case of fall sowing, any time during the winter, helps to conserve moisture as well as to give the growing plants some nitrogenous food. Applying a top-dressing of stable manure at least every second or third winter is certain to prove profitable. If it contains coarse straw or other litter, this should be raked and hauled off later, but before the alfalfa grows too high, especially if the hay is intended for the city market. Many successful growers in Kansas, who claim to cut from five to seven tons of alfalfa hay per acre in a season apply a top-dressing of manure every winter. The highest yields reported from eastern states are where this practice is followed. Some experiment station men believe that where this is not done the crop will after eight or ten years tend to impoverish the land instead of further improving it.
DISKING
The foremost method of cultivation is with the disk harrow, one of the most excellent farm implements ever invented. Alfalfa sown in the fall is almost invariably helped by disking the following spring, with the disks set quite straight, so as not to cut the crowns but to split them. It is usually well to follow this disking with a tooth harrow, with its teeth set straight. Occasionally in a dry summer the disk may be used to great advantage after the second, and possibly the third, cutting also. Many disk their alfalfa field every spring, and some after each cutting, others do so only once in every two or three years, owing to weather conditions and the conditions of the alfalfa. In some instances the common harrow is used instead of a disk.
The disking has several beneficial effects. It splits and spreads the crowns, causing more and consequently finer stems to spring up, affording hay of the most delightful quality, easily cured; it loosens the soil about the crowns, conserves moisture and destroys the weeds. There need be no fear of killing the plants if the disks and the harrow-teeth are set straight and weighted or otherwise adjusted to give direct and steady forward movement. As an implement for the cultivation and invigoration of an alfalfa field the disk harrow has no equal, and its frequent use is by those who know it best deemed quite indispensable.
RESEEDING
If it is a question of reseeding the whole field, the problem is simple. In that case disk and harrow the ground and sow half as much seed as was sowed at first. But to restore bare spots is more difficult; the young plants from the reseeding in these spots will be shaded by the larger growth about them, and such reseeding seldom gives the desired results. There is no doubt that very many fields are given up as failures and inferior crops planted in them, when a thorough disking would have renewed the growth, saved a crop, and, what is more important, a stand of alfalfa. Many reports have come to the writer of fields that had little sign of life the first of March, yet when thoroughly disked, cross-disked and harrowed, surprised the neighborhood by showing in two weeks a strong growth.
Some wishing to be on the safe side, have sown a little seed after this heavy disking and harrowing, but many of them have reported an entire loss of the seed, as the plants from the previous sowing came up so thick as to choke out those from the later seeding. In some states a common plan of thickening a stand is to let the third crop ripen seed, and then about the last of September disk and harrow the seed into the ground where it grew. This frequently saves the stand and adds many years to its life. But where a field begins to fail after a third year it is usually better to plow it up and raise one or two crops of corn, a crop of oats or of millet, and then reseed.
ALFALFA UNDER IRRIGATION
The greatest yields of alfalfa are produced by irrigation. Reported yields of six or more cuttings, aggregating eight to twelve tons per acre each year, are almost invariably, yet not always, from districts where irrigation is practiced. It is claimed by experiment station experts from the irrigation states that the tendency is to use too much water; too much at a time and too often. The general recommendation is to irrigate thoroughly before the ground is plowed or disked, and not again till the alfalfa is about four inches high. Then again a week before each cutting. It has been found that old alfalfa fields do not need as much water as new fields, the alfalfa roots seeming to find moisture and bring it to the surface.
It is insisted that the surface must be perfectly smooth to keep water from settling into low places and smothering the plants. Some farmers do not irrigate for the second crop if as much as two inches of rain falls after the first mowing. Others claim that old fields do not need flooding for the second crop even if there has been no rainfall after the first cutting.