Nitrogen guidelines
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.
Reviewed in 2023