Sheep grazing reduces pesticide use in alfalfa

 
Of the approximately half-million acres under irrigation in Imperial County, almost half is seeded to alfalfa which had a gross value in 2001 of $144,846,000. A continuing problem is winter weed control in alfalfa. Each year 200,000 to 300,000 lambs graze winter alfalfa in Imperial County, the largest concentration of sheep in the nation during that period.

 

 
In the late 1990’s, in collaboration with UCCE Weed Science Advisor Carl Bell, we compared lamb grazing with herbicides for weed control in seedling alfalfa. Three trials demonstrated that grazing lambs were just as effective as herbicides in controlling winter weeds. In 2001 and 2002, in collaboration with Entomology Advisor Eric Natwick, grazing lambs were compared to insecticides for insect control in winter alfalfa. In this two-year trial, lambs provided insect control as effectively as insecticides.
 

 
Today, as a result of this research, alfalfa growers often complain that there are not enough sheep during the winter for weed control in alfalfa. The need for herbicides has been reduced, thereby improving drain water quality. Lamb grazing of alfalfa benefits the sheep industry because the demand for lambs for grazing increases, and benefits the environment because the need for pesticides decreases.
 

Supporting Unit: Imperial County
 
Juan N. Guerrero, Area Livestock Advisor, 1050 E. Holton Road, Holtville, 92250 (760)352-9474
jguerrero@ucdavis.edu