04/01/1991

Sweet Lupins Promising for Alabama Farmers

MONROEVILLE, ALA.—Sweet lupin may provide a double boost in the future to Alabama farmers, according to Alabama Agricultural Experiment Station researchers. The legume crop produces grain that can be fed without processing to livestock, and at the same time leaves up to 90 pounds of nitrogen per acre for subsequent crops.

Randy Akridge, superintendent of the Monroeville Experiment Field, noted that full season white lupin has performed well in tests at the Auburn University research facility. "This is just our third year working with lupin, and we have produced yields of 35-40 bushels per acre," Akridge said.

Lupin can be crushed on the farm and fed to livestock without the need for processing, giving it a big advantage over soybeans and other grains. It typically has about 35 percent protein, compared to 42 percent for soybeans. High quality lupin also contains about 10 percent oil, and all these attributes combine to make it a good protein supplement for livestock rations.

Wayne Reeves, an agronomist with the U.S. Department of Agriculture's Agricultural Research Service and adjunct Experiment Station researcher, has worked with lupin at several locations in Alabama. Though enthusiastic about the crop's potential, Reeves cautions that it has many problems to overcome before it can be grown, even on a limited scale, by Alabama farmers. Reeves pointed out that a multidisciplinary group of researchers in Auburn's Ag Experiment Station, including plant breeders and plant pathologists, are already involved in the lupin project. "We think the winter hardy, or full season lupin, will ultimately be the choice in Alabama. Currently only one variety, TiftWhite-78, can be grown here, but it is not available to growers because of susceptibility to Phytophora, Pythium, Sclerotium rolfsii and a number of other soilborne diseases," Reeves noted.

Alabama was once a part of the lupin belt, but this was bitter lupins used solely for ground cover and to build nitrogen. These contain alkaloids that produce a bitter taste to animals, making them unacceptable for livestock feeds. Consecutive freezes and curtailment of government programs ended lupin production in Alabama in the early 1950s.

Reeves' initial interest in lupin was as a nitrogen-producing legume, but since the 1930s, plant breeders were able to genetically remove the bitterness, and new sweet lupin varieties produced seed highly palatable to livestock. Thus, his interest in developing production practices for sweet lupines with the dual use as a nitrogen fixer, and as a highly nutritious feed for livestock.

Winter hardy sweet white lupin was planted at the Monroeville Field in early November. "We have learned that the variety of lupin we're growing won't tolerate wet soil, and we have had problems with damping-off disease in young plants," Akridge commented. A subsoiler was used in the November 1990 planting and seed were planted directly into the raised rows. Thirty-inch row spacings on these raised rows has greatly reduced early diseases, and subsequent slow growth problems, according to the Auburn University researcher.

In addition to winter hardy full season sweet lupin, which are planted in late October and November and harvested in early June, Auburn researchers are looking at spring lupins, which are planted in February and March and harvested in late June. This is the first year of testing the two spring varieties, Ultra and Primorsky. Planting dates for these varieties were timed to come after the last days of 24, 28 and 32 degree F temperatures, or Feb. 7, Feb. 14 and March 14. The Auburn researchers are skeptical that the spring varieties can be planted early enough to get in the needed 130 days to seed set before daytime temperatures reach the mid 1980s, at which time seed development ceases.

Akridge explained that planting date is critical, because lupins are susceptible to cold temperatures during two growth stages: shortly after emergence and during bloom. For full season lupins this should not be a problem in south Alabama. Lupin's cold hardiness is documented by the full season variety at the Monroeville Field, which survived 15 degree F. cold in February with no damage. However, winter is usually Alabama's rainiest season, which adds drainage problems and increases disease woes.

In tests so far, researchers have used 30- to 36-inch rows, though tests have been conducted on row spacings as narrow as seven inches. Planting depth is critical with lupins, according to Akridge. "The seed don't seem to be able to handle planting more than an inch deep. They come up, but they seem to use all their energy getting out of the ground, and simply don't continue to grow," Akridge explained.

Despite the many problems in growing lupin, the opportunity far outweighs these disadvantages, according to Reeves. "In the South, we spend about $68 million annually on nitrogen fertilizer to grow wheat. Heavy rainfall during the time fertilizers are applied to wheat contribute heavily to it being an inefficient user of nitrogen (N), which can lead to heavy concentrations in runoff, leading to environmental problems. Lupin produces its own nitrogen, with some left over for rotation crops.

Lupin also grows well on poor soil, because it requires no N and little other residual fertilizers. But its biggest advantage is that it can be grown, crushed on the farm and fed directly to livestock. In Alabama, where most feed grain is brought in from other states, and both the poultry and beef cattle industries are growing, a new feed source for livestock, plus the double dividend of nitrogen, makes lupins look promising indeed.

-30-

By:
Roy Roberson