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Oklahoma State University Stillwater, OK |
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Oklahoma Alfalfa |
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Oklahoma State University Stillwater, OK |
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Oklahoma Alfalfa |
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Alfalfa Management During Drought |
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For several years prior to 1998, we became used to rainy summers in most of Oklahoma, and excess water had been a bigger problem than not enough water during several summers for most of the alfalfa producers in the state. In 1998, things have changed. High temperatures, little or no rain, and little moisture reserves have combined to bring up several questions recently. How can we make high quality hay during this weather? I think alfalfa producers should change their target market for alfalfa hay during the hottest part of the summer. It is always hard to make good tonnage and high quality during hot weather because the alfalfa develops so quickly. It is hard to harvest early enough to catch it when protein and other quality factors are good. If you normally try to make hay for the dairy or horse markets, reorient your harvest timing to make hay for beef cattle. Wait to harvest until it is in full bloom or when you have at least a ton of hay per acre. What is the most drought resistant alfalfa variety? The best alfalfa variety for good conditions (rain or irrigated) is the best under drought conditions. Alfalfa is one of the most drought-resistant crops. It has a vast root system which can get to moist soil, if it is there. When it does not find water, alfalfa goes dormant -- rather than trying to grow without enough water. Alfalfa can live during prolong droughts. When rains return, it will start growing again. This is not to say that alfalfa can produce high yields without large quantities of water. Alfalfa uses large amounts of water to produce high yields. It requires about 6" of water available to the root system to produce a ton per acre. We have compared alfalfa variety yields during droughts with their yield during "normal times." The yield goes down for all varieties, but the ranking of varieties remains about the same. The most striking information is that the "good" varieties (as evaluated over many years) tend to have the highest yield during dry years. When choosing an alfalfa variety, pick the one that is best over the long haul, not just for one cutting. Stick with the best varieties for dry or wet years. Does it hurt to irrigate alfalfa right after harvesting hay? Yes, there is a certain danger from irrigating while there is no leaf canopy during the summer. Scald in alfalfa is caused when standing water covers the soil and direct bright sunlight heats the soil and water. After a few inches of regrowth foliage shades the soil and plants are normally unharmed by standing water during bright sun. Plants growing without shaded soil suffered from scald. Most scalded plants die during a few days or weeks. If you have sprinkle irrigation move the sprinkle line quickly enough the first time around so that water does not stand for more than an hour. Then, the other irrigations can allow water to stand because plants will shade the soil from direct sunlight.
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| John Caddel, Forage
Agronomist Department of Plant and Soil Sciences Oklahoma State University |
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