Alfalfa often needs to be fertilized in the spring to assure profitable yields, but how much should you apply?

Acid soils can jeopardize alfalfa seedlings. Learn more.

With increasing fertilizer costs and strong land use competition from other crops, the best way to answer that question is with a soil test. Soil tests tell you how much of a given nutrient the soil can provide. Based on that you can determine how much more fertilizer, if any, should be applied for maximum profits.

Remember that alfalfa gets most of its nitrogen from the air if the plant roots are well-nodulated. Adding nitrogen is usually just a waste of time and money. 

All other nutrients must come from the soil or from fertilizer.

Many soils in our region provide high quantities of most nutrients, but very few soils provide all the nutrients needed for top alfalfa yields. That's why fertilizer often is needed.

Soil Testing

Collect soil samples as soon as frost is gone from existing alfalfa fields and any fields you plan to plant to alfalfa this spring or fall. Send these samples to a lab for analysis of phosphorus and soil pH.  If your field is sandy, eroded, or highly weathered, also test for potassium and sulfur.

Most important of all, use the results of these soil tests, with advice from your extension educator and fertilizer dealer, to develop an alfalfa fertilizer program designed for your conditions.  Better alfalfa profits will be the result.

Resources

These UNL Extension resources also may be helpful:

• Guidelines for Soil Sampling (G1740)  —  Proper procedures to collect representative soil samples.
• Soil Test Nebraska — Calculate fertilizer recommendations for all Nebraska crops

Bruce Anderson
Extension Forage Specialsit