Why is Arizona #1 in alfalfa per acre?
A desert state gets more alfalfa hay out of each acre than any other state. The story runs through canals dug by hand long ago, a big dam, a plant that does not take the winter off — and a river whose water is being cut back.
Arizona cuts more alfalfa hay from each acre than any other state USDA reports. That is a per-acre yield: it measures what one acre gives, not how much the whole state grows. Alfalfa is a leafy plant grown as hay (dried food for cows and other farm animals). Check the ranking in the quiz below.
Basis: USDA NASS Quick Stats, HAY, ALFALFA - YIELD, MEASURED IN TONS / ACRE, 2025 annual crop survey. The numbers, the full ranking and the source are on the quiz page.
Farming the desert with river water is very old in Arizona. The Park Service says the Hohokam people are probably most famous for their irrigation canals (ditches that carry river water to fields) along the Salt and Gila rivers — the largest and most complex irrigation systems of any culture in the New World north of Peru. Hohokam farmers grew crops in the same places for hundreds of years.
Who says so: National Park Service (opens in a new tab)
Much later, settlers dug a canal on the ancient Hohokam lands and founded Phoenix. But the Salt River was unpredictable: sometimes a flood, sometimes a trickle. After terrible droughts, farmers asked the federal government for help, and Roosevelt Dam was built in the mountains to store water for summer, dedicated by President Theodore Roosevelt in 1911. The Park Service says it was built to store water that would, in time, turn desert soil into farmland.
Who says so: National Park Service (opens in a new tab)
The plant matters too. Alfalfa varieties differ in fall dormancy — how much they grow in the fall. The University of Arizona says nondormant varieties are usually planted where winters are mild, for their ability to grow in the fall, and that the most nondormant kinds are adapted to the parts of Arizona below about 4,000 feet. Where frosts and freezes come again and again, that fall growth may be unwanted: semi-dormant and dormant varieties are adapted to colder-winter areas above about 4,000 feet, and a middle kind can be grown in between, from about 3,000 to 5,000 feet.
Who says so: University of Arizona Cooperative Extension (opens in a new tab)
In Pinal County, a big farming county in central Arizona, most of the surface water (water from rivers and lakes, not from underground) is Colorado River water delivered by the Central Arizona Project canal. With water levels low in Lake Mead, deliveries to farmers have been cut, and University of Arizona water researchers say agriculture bears the brunt of the cuts. Shortages may lead to fewer irrigated acres and/or more pumping of groundwater (water stored underground) — how much is not yet known. One idea already growing there: guayule, a drought-tolerant shrub that needs half the water of crops like cotton and alfalfa.
Who says so: University of Arizona Water Resources Research Center (opens in a new tab)
Another answer could be less water lost to the air. A state program run by University of Arizona Extension helps farmers and ranchers switch from flood irrigation to drip or sprinkler systems, which cut water loss from evaporation; to join, a farm must show it would save at least a fifth of its water. The applicants grow mostly wheat, alfalfa and leafy greens.
Who says so: University of Arizona Cooperative Extension (opens in a new tab)
Note: a “theory”, “folklore” or “outlook” is not settled fact. Always check who is saying it.
📊 Sources for the rankings mentioned in this note (links to the original data and retrieval dates) are on each quiz page below.