So many people ask me what they should use for fertilizers for their food plots. My answer is not as simple as most want it to be. Here are factors that come into play.
1) What are your soil test levels of phosphorous and potassium?
2) What is your soil pH?
3) What is your soil organic matter levels?
4) What are you planting?
5) What is your yield goal of what you are planting?
Why are each of these things important? Everything in life is about balance. You need to know if your deficient, sufficient or in excess of the major minerals in your soils. You might need to apply a larger amount of fertilizer than you expected or perhaps you are already at a desired level and using more will cause imbalance.
Soil pH is the most important consideration. It is the best first dollar to spend on food plots. Here is a why.
A soil with a pH of 5.0 is 10 times as acid than one with a pH of 6.0 and 100 times more acid than one with pH 7.0 because the pH scale is based on logarithms So just “a little” change in your pH from year to year can mean a lot to your plants. Usually if your soil is at 6 or somewhere above, you do not need to add any lime. If your pH is below 6 then you need to think about making lime applications.
If the pH is 4.5, about 75% of applied fertilizer may be unavailable to plants
If the pH is 5.0, about 54% of applied fertilizer may be unavailable to plants
Ifthe pH is 5.5, about 33% of applied fertilizer may be unavailable to plants
If the pH is 6.0, about 20% of applied fertilizer may be unavailable to plants
If the pH is 7.0, about 0% of applied fertilizer should be unavailable to plants
What are your soil organic matter levels? This is important because organic matter helps hold nutrients. If your putting down fertilizer and it's getting washed past the root zone you will have loss. You also might need to use split applications versus a single application if you have low organic matter levels.
What are you planting? This is important as you will see on the chart below. Some forages and grains mine a lot more potassium and phosphrous than others. Know what your taking away from the soil based on what yields your expecting.
What are you removing from the soil. Here is a chart i made up that shows how much p and k your removing from the soil per ton or per bushel for various crops you might plant.