This year, the local alfalfa producers are looking to receive only about one-third of the irrigation water they would normally receive due to the lack of water flow in the Humboldt River. 

The recent rains were helpful in providing some much-needed precipitation, but will not be enough to sustain their crops during the summer months.

Often, during drought conditions, the public looks for ways to conserve water resources, and some look at agriculture as not being the best use of our water. Many are critical of growing alfalfa during drought conditions, because they say it is using more water than other crops.

In order to address this accusation, I would like to share an article written by Dan Putnam, Forage Specialist, University of California Davis Cooperative Extension, Why Alfalfa is the Best Crop to have in a Drought:

The 2013-2015 drought brought much public attention to the amount of water used in agriculture, and particularly which crops use the most water. Alfalfa is often one of the favorite whipping boys of agricultural critics due to its high water use on a state-wide basis.



But is alfalfa’s water profile really so miserable?  

Contrary to popular belief, alfalfa has several unique positive biological properties and advantages when it comes to water. Due to these properties, alfalfa is remarkably resilient when it comes to severe drought conditions.



First a clarification — Alfalfa does not really use more water than other crops. At full canopy (when the leaves cover the soil surface), alfalfa’s water use is not much different than any other crop (think spinach, lettuce, tomato, wheat, almonds or corn) per unit time. The evapotranspiration (ET) requirement (the amount of water a crop really needs to grow) is remarkably similar across crops at full canopy.

Alfalfa’s water use profile is primarily due to its high acreage and nearly year-round growth pattern in many regions.  If spinach were continually grown on comparative alfalfa acres all year long, the 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 water that is important – also known as water-use efficiency. In that category, alfalfa shines.

Contrary to popular belief, alfalfa has several unique valuable properties and advantages which would enable cropping systems greater resiliency under drought conditions.

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 are:



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 moisture residing deep in the profile when surface waters become scarce. It shares this property with crops such as orchards, vineyards, and sugar beets and safflower, unlike crops such as onion, lettuce and corn, where it’s easy to lose water past the root zone.



Perenniality — The fact that the crop grows for 4-8 years, grows quickly with warm conditions in the spring is a major advantage of alfalfa—it can utilize residual winter rainfall before irrigation is necessary. This is unlike summer-grown annual crops that need to be replanted each year (water use efficacy is low during this time). In many areas, the first cutting of alfalfa of the year requires zero irrigation– supported only by rain and residual soil moisture.



Very High Yields — Alfalfa is a very high yielding crop, and can grow 365 days a year in warm regions (such as the Imperial Valley of California and southern Arizona). Its biomass yields are very high—we can get up to 12 cuttings per year in those regions, and growers with top management can obtain more than 14 tons/acre dry matter yields. High-yields create higher water use efficiencies.



High Harvest Index, High Water Use Efficiency — Alfalfa’s Water Use Efficiency is not only due to high yields, but because nearly 100% of the above-ground plant material is harvested (known as the harvest index). In most seed-producing and fruiting crops, only a portion of the plant is harvested (typically 30-50% of the total plant biomass).



Salt Tolerance/Ability to Utilize Degraded Water — Recent data has shown that alfalfa has a high degree of salt tolerance. A recent trial in Fresno County, where EC (Electrical Conductivity) 5.5 water was used for irrigation over 3 years, yields were normal (10-12 tons/acre). This is important in a drought, since degraded recycled water (municipal waste water, drain water, other waste water) could be used on this crop, while saline waters would injure less-tolerant crops.



Ability to Survive a Drought — Alfalfa evolved in regions of the world with long hot dry summers and wet winters. Although yields are highest with full irrigation, alfalfa can survive periodic droughts. This is due both to deep roots as well as ability to go ‘summer dormant’ under dry conditions. In 2014, Central Valley growers that were forced to stop watering their alfalfa fields generally found the crop recovered after rainfall or irrigation resumed later in the year.

In summary, Contrary to some popular views, alfalfa has a range of positive biological characteristics that should be quite useful when facing water-short conditions. These characteristics include a high degree of flexibility to ‘deficit irrigate’ the crop, ability to survive drought periods, high water-use efficiency, deep rootedness, salinity tolerance, and the ability to utilize degraded water.  It is additionally very valuable to wildlife, which also suffers during a drought. Oh, and by the way, it is also very valuable to the millions of consumers who depend upon the milk, cheese, yogurt, and yes ice cream, produced from alfalfa.