Alfalfa crop remains stable at 20.982 million acres

Although the number of acres dedicated to alfalfa and alfalfa mixes rose only 2,000 acres during the past year, yield on that acreage rose 3.4 percent, reveals data in the October 2009 Crop Production published by the National Agricultural Statistics Service (NASS). In all, there were 20.982 million acres of alfalfa in U.S. farm fields this past year. That land produced 71.977 million tons of forage with an average yield of 3.43 tons per acre.

Among the top dairy states, California produced 6.533 million tons of alfalfa which was tops in the U.S. That forage came from some 975,000 acres. Impressive as those totals are, California's production is down 8.3 percent from 2007 when California produced 7.128 million tons of forage.

South Dakota, with 2.4 million, and Montana, with 1.65 million acres, are tops in the nation for land dedicated to the crop. Next comes Wisconsin with 1.55 million acres which yielded 4.185 tons of forage (sixth in the nation). Minnesota ranked fifth in acres and tons with 1.25 million acres that produced 3.5 million tons. Idaho, top five dairy state harvested 4.674 million tons of alfalfa (third most in the nation) from 1.14 million acres (sixth nationally). Of note, Pennsylvania recorded the largest yield increase, producing 3.7 tons per acre which compares to 3 tons last year.

How will an early frost affect forages?

An early frost in many parts of the country has dairy producers asking, “What effects will the frost create for livestock feeds?” says Dave Fischer, University of Illinois Extension dairy educator. Following frost, producers should be cautious when grazing cattle with crops in the sorghum family. Grazing other grasses and legumes will not be a problem.

• Grazing sudangrass, sorghum-sundangrass hybrids, grain/forage sorghum. These crops are members of the sorghum family and will produce a glucoside called dhurrin that breaks down to release a toxin called prussic acid. A crop stress, such as frost, causes the prussic acid to be released at a rapid rate and the intake of high levels may be lethal to cattle. Clinical signs of prussic acid poisoning include rapid pulse, labored breathing, and eventual suffocation. Producers should move cattle away from grazing these forages for several days following a frost. If the crop was safe to graze prior to frost it, will again be safe to graze 3 to 5 days following the frost. Remember, sudangrass should be greater than 18 inches tall or sorghum-sudangrass greater than 24 inches before it is safe to graze under any conditions.

• Baling or ensiling sudangrass, sorghum-sundangrass hybrids, and grain sorghum immediately following or shortly after a frost is safe because the prussic acid will break down and dissipate during the harvesting process. Therefore, waiting 7 to 10 days after harvesting those crops made into hay or silage will be safe to feed. However, allowing the feed to cure or ferment in the silo or bale for 2 to 3 weeks before feeding will give you an added safety factor, says Fischer. Certainly, do not feed the material as green-chop.

• Grazing alfalfa, clover, and other perennial forages is not a concern following a frost because they do not produce toxins and can be grazed or baled and fed to livestock even after a frost. The only caution will perhaps be a slight chance for ruminants to bloat if grazing pure legume pastures. They should be offered other feedstuffs to avoid overeating the succulent pasture.

• Harvesting alfalfa after a killing frost is acceptable only when the plant is going into dormancy. This killing/dormant frost occurs when temperatures reach 28 degrees Fahrenheit, or lower, overnight (4 hours or more). If the plants are harvested predormancy and regrowth occurs 1 to 2 weeks before going dormant, significant plant damage can occur during overwintering due to reduced food reserves in the plant to survive the cold temperatures, notes the Illinois Extension specialist. If the forage is not needed, it is advisable to leave the crop uncut for the winter.

• Immature soybeans that are caught by the frost due to late plantings can be harvested for forage if the crop is free from applied pesticides. The soybean forage should be cut, wilted, and harvested at similar moisture levels as would be used for alfalfa or other legumes. It is best to begin harvest no later than when the bottom leaves turn yellow and begin to drop off. Since late fall drying conditions are very marginal, chopping as silage is preferred over baling.