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.
Wilcox in his “Irrigation Farming”[3] says: “The critical time with alfalfa is the first six weeks of its growth. Flooding during this period is quite certain to give the plants a backset from which they seldom fully recover before the second, and sometimes not before the third year, and it is not often in the arid states that rain falls with sufficient frequency to dispense with the necessity for irrigating the plants while small. By soaking the earth from thirty-six to forty-eight hours before seeding, however, the plants will make vigorous growth until they are ten to twelve inches high, after which they may be irrigated with safety.
[3] “Irrigation Farming,” by Lute Wilcox: 314 pp. Orange Judd Company, New York.
“When alfalfa has become established, a single copious irrigation after each cutting will ordinarily be found sufficient. Irrigation before cutting is undesirable, because it leaves the earth so soft as to interfere with the movement of machinery and loads. It also makes the stalks more sappy, and, while they will retain the leaves better, there is more difficulty to be experienced in the curing at harvest time; and taken all in all, we much prefer to irrigate after each cutting. In Colorado we cut alfalfa three times and often four times in a season, hence the stand gets as many irrigations. Some people irrigate very early in springtime, before the crowns have awakened from their hibernal rest, but this practice is not right. The chill of the water in very early spring is not conducive to quick growth and may often retard the plants in getting an early start. We do not irrigate prior to the first cutting unless the season is particularly dry and the plants seem to actually demand water. We irrigate late in the fall and apply a top-dressing of light barnyard manure, which is found to be of great service in several ways.”