Soil pH and liming guidelines
Maintaining an optimum soil pH can be critical for the growth and development of many crops. Legumes such as alfalfa and alsike clover require higher soil pH levels than other crops.
Many soils where food plots are established have a history of forest vegetation. These soils tend to have low soil pH levels. In these cases, a soil test will typically indicate a need for lime application. Since liming soil requires 2 to 3 tons of material per acre, you must determine whether it is feasible to haul and apply lime to areas where food plots are established.
Grasses and red clover typically grow well when soil pH is less than 6.0. Selecting tolerant plant species is critical. Since most crops for wildlife food plots are not grown for maximum yield, liming rates could be reduced or eliminated.
If equipment is available for lime application, lime should be applied before establishment when it can be incorporated. If lime can be applied, it is suggested that enough should be broadcasted to raise the pH of the soil to 6.0.
Lime suggestions for mineral soils when the soil pH is less than 6.0*
| Buffer index | Area 1: ENP lb/acre | Area 1: Ag Lime** ton/acre |
Area 2: ENP lb/acre |
Area 2: Ag Lime** ton/acre |
|---|---|---|---|---|
| 6.8 | 2000 | 2 | 0 | 0 |
| 6.7 | 2000 | 2 | 0 | 0 |
| 6.6 | 2000 | 2 | 0 | 0 |
| 6.5 | 2500 | 2.5 | 0 | 0 |
| 6.4 | 3000 | 3 | 2000 | 2 |
| 6.3 | 3500 | 3.5 | 2000 | 2 |
| 6.2 | 4000 | 4 | 2000 | 2 |
| 6.1 | 4500 | 4.5 | 2000 | 2 |
| 6 | 5000 | 5 | 2500 | 2.5 |
*The rates suggested should raise the pH to 6.0.
**These are approximate suggestions based on the average ENP value of Ag lime. An ENP of 1,000 lb per ton is the average value for Ag lime (crushed limestone) in Minnesota.
Nitrogen management
Optimum nitrogen management is critical to increase plant growth and also to maintain plant establishment on a year-to-year basis. Legumes, such as well-nodulated alfalfa and clover, can produce enough nitrogen to satisfy the plants' requirements. Grasses do not produce their own nitrogen, so fertilizer nitrogen should be applied under these circumstances.
Nitrogen can be applied in a single surface application at or before rapid plant growth periods. The full recommended nitrogen rate may not be needed. The amount will depend on when you plant and the amount of growth desired from the plants. For late plantings, nitrogen rates can be cut back considerably. A minimum rate of 30 pounds of N is suggested for maintaining a stand with a maximum application of no more than 60 pounds of N.
Phosphorus and potassium
Current research on phosphorus and potassium management in food plots is limited. However, if a crop is not harvested, P and K taken up by the plants will be recycled for the next season’s use and therefore not lost through the removal of crop material.
Current guidelines for individual crops consider maximum economic yield. For wildlife food plots, it is suggested that rates be reduced for individual crops since economic yield is not a consideration.
The rates listed in the tables below are appropriate for broadcast applications. Soil test results are reported in parts per million (ppm).
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+ ppm 12+ ppm |
|---|---|---|---|---|
| Corn/forage brassicas | 25 lb/acre | 20 lb/acre | 15 lb/acre | 0 lb/acre |
| Grass | 25 | 20 | 15 | 0 |
| Legume/grass | 35 | 25 | 15 | 0 |
| Oat/wheat/rye | 35 | 25 | 15 | 0 |
| Soybean | 30 | 15 | 0 | 0 |
| Sugarbeet/turnip | 35 | 25 | 15 | 0 |
Potash guidelines
| K soil test result | 0-40 ppm | 41-80 ppm | 81-120 ppm | 121+ ppm |
|---|---|---|---|---|
| Corn/forage brassicas | 60 lb/acre | 40 lb/acre | 25 lb/acre | 0 lb/acre |
| Grass | 40 | 30 | 20 | 0 |
| Legume/grass | 40 | 30 | 20 | 0 |
| Oat/wheat/rye | 40 | 30 | 20 | 0 |
| Soybean | 60 | 40 | 25 | 0 |
| Sugarbeet/turnip | 40 | 30 | 20 | 0 |
Secondary and micronutrient guidelines
- For most crops grown in wildlife food plots, secondary or micronutrients should not be needed for optimal growth.
- In sandy soils, a small amount of sulfur may be needed for legume and grass mixtures. In these cases, 10 to 15 pounds of sulfur per acre should be applied with the nitrogen application.
- Some nitrogen can be substituted with ammonium sulfate (21% N and 24% S) to provide sulfur for the plants.
- Gypsum can be surface applied to supply needed sulfur however gypsum does not have a liming effect on the soil.
Reviewed in 2024