Soil Test New and Established Alfalfa

Soil Test New and Established Alfalfa

March 6, 2015

Alfalfa is a hungry crop and often needs to be fertilized in the spring to produce a profitable yield.

With increasing fertilizer costs and strong land use competition from other crops, you want to apply the right amount of fertilizer to achieve optimum results, but how much is that? A soil test is the best indicator of how much fertilizer to apply. Soil tests tell you the amount of each nutrient your soil can provide to your alfalfa plants.  Then you can determine how much more fertilizer, if any, should be applied for maximum profits.

Alfalfa gets most of its nitrogen from the air if the plant roots are well-nodulated. Thus, nitrogen applications usually are not cost efficient; however, 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.

Soil Testing in Alfalfa

Collect soil samples as soon as frost is gone from existing alfalfa fields and fields you expect to plant to alfalfa this spring or next fall.  Send these samples to a lab for analysis of at least 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.

Bruce Anderson
Extension Forage Specialist

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