Alfalfa Nutrient Management Guide Megan Baker, Matt Yost, Clara Anderson, Grant Cardon, Jody Gale, Earl Creech, Cody Zesiger, and Kalen Taylor
Introduction
Alfalfa is the most important field crop grown in Utah because of our dry climate, the quality of feed produced, and economic return to farm businesses. Utah growers produce roughly 2 million tons of alfalfa hay per year, averaging 4.1 tons per acre in 2022 (National Agricultural Statistics Service [NASS], 2024). Much of the alfalfa grown in Utah feeds dairy and beef cattle, with some being exported. Proper nutrient management is key to maintaining high yields, quality, and stand longevity for profitable alfalfa production.
As alfalfa grows, it uses nutrients from the soil and air to form new tissue. Table 1 displays the amount of nutrients each ton of alfalfa removes from the soil during harvest. The nutrients that alfalfa and other plants remove from the air are relatively unlimited, but nutrients from the soil are limited by their concentration in the soil and root depth. Fertilizers and soil amendments are often used to supplement soil nutrients to supply the crop with the quantities needed for optimal growth. Alfalfa nutrient needs and fertilizer recommendations are determined by current soil test results, yield potential, field history, and soil nutrients being removed by the crop. In Utah, phosphorus (P) is the nutrient most often recommended in the highest quantities for alfalfa production. Several other nutrient deficiencies have been reported, but it greatly depends on field location, soil type, and field fertility history. Nutrient deficiencies can negatively impact crop yield, quality, economics, and stand life.
1
Highlights •
•
•
•
•
•
Proper nutrient management is key to maintaining high yields, quality, and stand longevity for profitable alfalfa production. Alfalfa nutrient needs and fertilizer recommendations are determined by current soil test results, yield potential, field history, and soil nutrients being removed by the crop. Tissue tests can be the most accurate way to diagnose a micronutrient deficiency in alfalfa. In Utah, phosphorus (P) is the nutrient most often recommended in the highest quantities for alfalfa production. By the time that visible symptoms of nutrient deficiencies appear, yield, quality, and economic losses have already occurred. Fertilizer applications can greatly improve crop yield and quality, and in turn, greatly increase economic returns.