Permanent subsurface drip irrigation systems can conserve water while maintaining or improving alfalfa yields.

That’s according to University of California irrigation specialists, who compared drip and furrow systems in a six-year study at Brawley, CA.

A drip system was installed about 16" deep in bed-planted alfalfa, with 40" and 80" lateral spacings. During the first one and a half years of the study, roughly 20% higher yields were achieved in drip- vs furrow-irrigated plots, with 6% less water used. But there were surface soil wetting problems in all drip treatments, so the alfalfa was removed and the drip lines were placed 25-28" deep.

During the next four years, water usage was similar between the two irrigation methods, but yields were 19-35% higher under drip irrigation. Placing the drip lines deeper solved the surface wetting problem, say the specialists.