A recent call from a CAFA member prompted a search of literature on alfalfa and water use. The grower farms in an adjudicated basin and is concerned that water allotments will be severely cut back or even eliminated.
The total amount of water used to grow alfalfa makes it an easy target. In his book, “Cadillac Desert,” the late Marc Reisner cited alfalfa as a high-water consuming crop that shouldn't be grown in California. He later softened his stance after meeting with members of the alfalfa industry who banded together to form CAFA.
A detailed analysis by UC Davis Professor Emeritus Robert Loomis, and Dutch researcher Jacco Wallinga, puts the issue of water-use efficiency in perspective. Annual water use in evapotranspiration by alfalfa may be high compared to other crops but total production is also high, they pointed out.
To evaluate whether alfalfa is ‘“water wasting,” Loomis and Wallinga compared research findings on water use by different crops, including corn for grain, sugar-beets, barley and dry beans. Barley grows during the cool season when water use is low and beans have a short life cycle, so very little water is used. On average, alfalfa produced 490 pounds of dry hay per acre for each inch of water consumed. That was confirmed at several California locations with a sophisticated model that simulates production and water use as functions of weather.
With good management, alfalfa growers can expect to produce about 3 tons of 12 percent hay per acre-foot of water, they stated.
“Alfalfa's water-use efficiency was more than corn (400 pounds of grain), sugar beets (340 pounds of sugar), barley (300 pounds of grain) and dry beans (110 pounds of beans) produced per acre-inch of water.” Loomis and Wallinga also calculated human-edible energy and protein that the crops could supply through different food chains, using feeding efficiencies reported in USDA and NRC handbooks.
“Direct consumption of beet sugar provided the most calories for human diets per unit of water. Feeding grain to dairy cattle provided the most human-edible protein per unit of water, followed closely by alfalfa as dairy feed, and a vegetarian diet of dry beans. All beef systems tested were inferior to dairy. The water-use efficiency of alfalfa in production of human-edible calories by the dairy route was ‘quite good’ and exceeded dry beans.”
Loomis and Wallinga noted that water use and conversion efficiency vary with climate and management. “The important point is that alfalfa conversion to human-edible calories and protein per unit of water use compares quite favorably with grain systems and with a vegetarian diet of beans. It also provides a higher dollar value for water than alternative systems.”
Superior water-use efficiency and excellent value as an animal feed explain why alfalfa is the principal forage crop throughout the world's semiarid and arid regions. In many regions, a small acreage of irrigated alfalfa provides critical supplies of forage that allow animals to graze much larger areas of sparse grasslands.
New Address For CAFA
In January, CAFA changed its mailing address to 36 Grande Vista, Novato, CA 94947. However, mail is still being accepted at P.O. Box 162, Davis, CA 95617-0162. Also, CAFA should now be contacted by phone at (415) 892-0167.