Beautiful alfalfa field. Leaves detail. Green.

Crop Nutrition

Preparing Your Alfalfa Stand For Success By Getting The pH Right

Robert Mullen, Ph.D.

Robert Mullen

Robert Mullen, Ph.D.

Nutrien

Director of Agronomy

To say Dr. Robert Mullen is passionate about agriculture would be an understatement. He holds a Bachelor of Science degree in ag business from Cameron University, along with a Master of Science degree in plant and soil science and a Ph.D. in soil science from Oklahoma State University. In addition, Dr. Mullen has been published in a variety of scientific and trade journals. But it’s not just his academic accomplishments that make him unique. It’s his unwavering ability to take complex data and — in simple terms — explain how it impacts a farmer’s bottom line. Dr. Mullen delivers the kind of insightful observations that can lead to a more profitable business. As a leading agronomy expert, Dr. Mullen has a goal to further educate farmers on best management practices that improve their yields and maximize their return on investment.

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Alfalfa is one of the most successful forage crops in North America.

  • It is…
    • A legume, so it does not need much, if any, supplemental nitrogen.
    • Well adapted to most of North America (except the southeastern U.S.).
    • A valuable forage crop for animal feed.
    • Highly productive and a single planting that, when well-managed, can provide forage for upwards of six years (Table 1).

Table 1. Alfalfa acres and average yields in the top 15 states in the United States in 2020.

State Harvested Acres (millions) Yield, tons/acre
Montana 1.90 2.2
South Dakota 1.80 1.8
North Dakota 1.22 1.8
Idaho 1.01 4.5
Nebraska 0.86 3.8
Wisconsin 0.84 3.2
Iowa 0.83 3.5
Minnesota 0.74 3.6
Colorado 0.70 3.4
Wyoming 0.61 3.1
Michigan 0.55 2.8
Utah 0.55 3.8
Kansas 0.54 3.7
California 0.48 7.2
Washington 0.41 4.4

One of the most important aspects of growing a high-quality, long-lasting stand of alfalfa is preparing the soil prior to seeding. Adequate levels of potassium and phosphorus are important for maintaining a high-quality alfalfa stand, but this article is going to focus on soil pH. Legumes prefer soil pH levels approaching neutral (pH around 7), and most universities recommend a pH of at least 6.5, if not 6.8.

A soil test will indicate what the current pH is, and if it is lower than the desired level, liming/neutralization is required. The buffer pH will indicate how much lime is actually required, but realize the amount required is dependent upon the pH level desired and the soil’s buffering capacity, often indicated by soil texture or cation exchange capacity (see this article for illustration).

Every state’s Department of Agriculture will likely have lime laws and employ different methods of determining the neutralizing potential of agricultural limes marketed in the state, so make sure you consult your land-grant university or local knowledgeable agronomist when making rate decisions.

Getting soil conditions prepared prior to seeding is critical to stand quality and duration.

For more information, see the following articles for Montana, North Dakota, Nebraska, Wisconsin, Minnesota, and Kansas.