Red clover, alsike clover & birdsfoot trefoil fertilizer recommendations

These legume crops, if properly inoculated, can take enough nitrogen from the atmosphere that they won't need fertilizer N after the crop is established. A small amount (less than 25 lb. N/ acre) may aid in getting successful establishment on sandy soils. Crops won't need fertilizer N for establishment on soils that are not sandy.

Table 1 summarizes the phosphate suggestions for these crops. The potash guidelines are in Table 2. You can topdress phosphate and/or potash fertilizers on established stands annually.  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.

In table 1 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)

Table 1: Phosphate fertilizer guidelines

Expected yield P soil test: 0-5 parts per million (ppm) Bray and 0-3 ppm Olsen P soil test: 6-10 ppm Bray and 4-7 ppm Olsen P soil test: 11-15 ppm Bray and 8-11 ppm Olsen P soil test: 16-20 ppm Bray and 12-15 ppm Olsen P soil test: 21+ ppm Bray and 16+ ppm Olsen
2 tons per acre 35 lbs. of P2O5 per acre 25 lbs. of P2O5 per acre 15 lbs. of P2O5 per acre 0 lbs. of P2O5 per acre 0 lbs. of P2O5 per acre
3 tons per acre 55 lbs. of P2O5 per acre 40 lbs. of P2O5 per acre 25 lbs. of P2O5 per acre 10 lbs. of P2O5 per acre 0 lbs. of P2O5 per acre
4 tons per acre 70 lbs. of P2O5 per acre 50 lbs. of P2O5 per acre 30 lbs. of P2O5 per acre 10 lbs. of P2O5 per acre 0 lbs. of P2O5 per acre
5 tons per acre 90 lbs. of P2O5 per acre 65 lbs. of P2O5 per acre 40 lbs. of P2O5 per acre 15 lbs. of P2O5 per acre 0 lbs. of P2O5 per acre

Table 2 summarizes potash recommendations for red clover, alsike clover and birdsfoot trefoil. 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)

Table 2: Potash fertilizer guidelines

Expected yield K soil test: 0-40 ppm K soil test: 41-80 ppm K soil test: 81-120 ppm K soil test: 121-160 ppm K soil test: 161+ ppm
2 tons per acre 95 lbs. of K2O per acre 65 lbs. of K2O per acre 40 lbs. of K2O per acre 15 lbs. of K2O per acre 0 lbs. of K2O per acre
3 tons per acre 140 lbs. of K2O per acre 100 lbs. of K2O per acre 60 lbs. of K2O per acre 20 lbs. of K2O per acre 0 lbs. of K2O per acre
4 tons per acre 185 lbs. of K2O per acre 135 lbs. of K2O per acre 80 lbs. of K2O per acre 25 lbs. of K2O per acre 0 lbs. of K2O per acre
5 tons per acre 230 lbs. of K2O per acre 165 lbs. of K2O per acre 100 lbs. of K2O per acre 35 lbs. of K2O per acre 0 lbs. of K2O per acre

Other nutrients

These legumes will 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. We suggest an application of 3,000 lb. ENP per acre for crops grown on acid soils. The lime should be broadcast and incorporated before seeding.

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 lb. S per acre when these crops are grown on sandy soils.

Daniel E. Kaiser, Extension nutrient management specialist

Reviewed in 2018

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