If spinach were continually grown on 850,000 to 1 million acres all year long, water use would be about the same as alfalfa, perhaps more.

Further, it's not so much how much water is used, but how much crop is produced per unit of water that is important – also known as water-use efficiency. In this category, alfalfa shines.

Alfalfa has a range of biological characteristics that make it very useful when a farm or an irrigated region is faced with drought conditions and resulting water limitations.

These include:

1 - Deep-rootedness - Alfalfa roots are commonly 3-5 feet deep and can extend to 8-15 feet in some soils. Therefore this crop can utilize deep moisture when surface waters are scarce.

2 – Perenniality - Unlike summer-grown annual crops replanted each year, alfalfa grows for 4-8 years, grows quickly with warm conditions in the spring, and can utilize residual winter rainfall before irrigation is necessary.

3 - Very high yields - Alfalfa is a high yielding crop, and can grow 365 days a year in warm regions. The tons produced per unit of water are thus very high – more crop per drop.

4 - High harvest index, high water use efficiency – Since the entire above-ground plant is harvested, the economic yield per unit of water is high, unlike other crops, where only a portion of the plant is harvested. 

5 - Salt tolerance-ability to utilize degraded water - Alfalfa has a high degree of salt tolerance, and can thereby use degraded recycled water (municipal waste water, drain water, other waste water) instead of fresh water.   

6. Contribution to wildlife habitat - In a drought, all of nature suffers. Alfalfa has been shown to be a significant wildlife habitat due to its lush foliage and insect diversity. Biologists have determined that 28 percent of California's wildlife use alfalfa for nesting, feeding, or cover. Even partial-season irrigation during drought can assist wildlife in surviving a drought period by using alfalfa as habitat.