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Extension > Agriculture > Nutrient Management > Nutrient/Lime Guidelines > Fertilizer Recommendations for Agronomic Crops in Minnesota > Wildlife Food Plots

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Fertilizer Recommendations for Agronomic Crops in Minnesota

Wildlife Food Plots

Daniel E. Kaiser, Extension Soil Scientist; John A. Lamb, Extension Soil Scientist; and Roger Eliason, Director, University of Minnesota Soil Testing Laboratory

Revised 2011

Soil pH and Liming

As with most grains, N management is 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. Liming guidelines are given in Tables 1 and 2. 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 a soil requires 2 to 3 tons of material per acre, consideration must be given to determine whether it is feasible to haul and apply lime to areas where food plots are established. Grasses and red clover will 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 prior to 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.

Table 1. Lime guidelines for mineral soils when the soil pH is less than 6.0. The rates suggested should raise the pH to 6.5.

SMP Area 1 Area 2
Buffer Index ENP Ag Lime* ENP Ag Lime*
  lb./acre ton/acre lb./acre ton/acre
6.8 3000 3.0 2000 2.0
6.7 3500 3.5 2000 2.0
6.6 4000 4.0 2000 2.0
6.5 4500 4.5 2000 2.0
6.4 5000 5.0 2500 2.5
6.3 5500 5.5 2500 2.5
6.2 6000 6.0 3000 3.0
6.1 6500 6.5 3000 3.0
6.0 7000 7.0 3500 3.5

*These are approximate guidelines based on the average ENP value of ag lime. An ENP of 1,000 Lb. per ton is an average value for ag lime (crushed limestone) in Minnesota.

Table 2. Lime guidelines for mineral soils when the BUFFER TEST IS NOT USED (Soil pH is 6.0 or higher). The rates suggested should raise the pH to 6.5.

SMP Area 1 Area 2
Buffer Index ENP Ag Lime* ENP Ag Lime*
  lb./acre ton/acre lb./acre ton/acre
6.5 0 0 0 0
6.4 2000 2.0 0 0
6.3 2000 2.0 0 0
6.2 3000 3.0 0 0
6.1 3000 3.0 0 0
6.0 3000 3.0 2000 2.0

* These are approximate guidelines based on the average ENP value of ag lime. An ENP of 1,000 Lb. per ton is an average value for ag lime (crushed limestone) in Minnesota.

Nitrogen Management

Optimum nitrogen management is critical not only to increase plant growth but 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. Plants such as 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 prior to rapid plant growth periods. The full recommended nitrogen rate may not be needed. The amount will depend on the time of planting and amount growth desired from the plants. For late plantings, nitrogen rates can be cut back considerably. A minimum rate of 30 lbs of N is suggested for maintaining stand with a maximum application of no more than 60 lbs of N. Phosphorus and Potassium

Phosphorus and Potassium

Current phosphate guidelines are listed in Table 3 for separate food plot plant mixtures. Guidelines for potash use are in Table 4. The rates listed are appropriate for broadcast application. Current research on P and K 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.

Table 3. Phosphate fertilizer suggestions for wildlife food plots in Minnesota.

    Phosphorus (P) Soil Test, ppm
Crop Mixture Bray: 0-5 6-10 11-15 16-20 21+
Olsen: 0-3 4-7 8-11 12-15 16+
    — P2O5 to apply (lb./acre) —
  Corn/Forage Brassicas   25 20 15 0 0
  Grass   25 20 15 0 0
  Legume/Grass   35 25 15 0 0
  Oat/wheat/rye   35 25 15 0 0
  Soybean   30 15 0 0 0
  Sugar beet/turnip   35 25 15 0 0

Table 4. Potash fertilizer suggestions for wildlife food plots in Minnesota.

  Potassium (K) Soil Test, ppm
Crop Mixture 0-40 41-80 81-120 121-160 161+
  — K2O to apply (lb./acre) —
  Corn/Forage Brassicas 60 40 25 0 0
  Grass 40 30 20 0 0
  Legume/Grass 40 30 20 0 0
  Oat/wheat/rye 40 30 20 0 0
  Soybean 60 40 25 0 0
  Sugar beet/turnip 40 30 20 0 0

Secondary and Micronutrients

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 10-15 lbs 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.

 

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