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Fertilizing red clover, alsike clover and birdsfoot trefoil

Nitrogen guidelines 

A field of red clover.

These legume crops, if properly inoculated, can take needed nitrogen from the atmosphere and fertilizer N will not be needed after the crop is established. A small amount (less than 25 lb. N/acre) may aid in establishment on sandy soils. You do not need nitrogen fertilizer for establishment on soils that are not sandy.

Lime requirements

These legumes respond to the application of lime if the soil pH is less than 6.0. Lime suggestions for these crops have not been well defined. An application of 3,000 lb. ENP per acre is suggested for these legumes grown on acid soils. The lime should be broadcast and incorporated before seeding.

Phosphate and potash guidelines

Phosphate and potash fertilizers can be top-dressed to established stands on an annual basis. The suggested rates of these two nutrients can also be broadcast and incorporated before seeding. This management practice may help in achieving a satisfactory stand.

Phosphate fertilizer guidelines

Expected Yield Bray-P1
Expected Yield Olsen
0-5 ppm
0-3 ppm
6-10 ppm
4-7 ppm
11-15 ppm
8-11 ppm
16-20 ppm
12-15 ppm
21+ ppm
16+ ppm
2 tons/acre 35 lb/acre 25 lb/acre 15 lb/acre 0 lb/acre 0 lb/acre
3 tons/acre 55 40 25 10 0
4 tons/acre 70 50 30 10 0
5 tons/acre 90 65 40 15 0

Use one of the following equations if you want a phosphate guideline for a specific soil test and a specific expected yield:

  • Recommended P2O5 =  [20 - (1.0) (Bray P in ppm)] (Expected yield)
  • Recommended P2O5 =  [20 - (1.4) (Olsen P in ppm)] (Expected yield)

Potash fertilizer guidelines

Expected Yield 0-40 ppm 41-80 ppm 81-120 ppm 121-160 ppm 160+ ppm
2 tons/acre 95 lb/acre 65 lb/acre 40 lb/acre 15 lb/acre 0 lb/acre
3 tons/acre 140 100 60 20 0
4 tons/acre 185 135 80 25 0
5 tons/acre 230 165 100 35 0

Use the following equation if you want a potash guideline for a specific soil test and a specific expected yield:

  • Recommended K2O = [53.28 - (0.333) (Soil test K in ppm)] (Expected yield)

Other nutrients

Except for the need for sulfur (S) when these crops are grown on sandy soils, other nutrients are not needed in a fertilizer program. Use an annual broadcast application of 25 pounds of S per acre when these crops are grown on sandy soils. An application of 10-15 pounds of S may be needed when these crops are grown on medium to fine textured soils when the soil organic matter concentration in the top 6-8 inches is 3% or less.

Daniel E. Kaiser, Extension nutrient management specialist, and Keith Piotrowski, director of the soil testing laboratory

Reviewed in 2023

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