Soil Testing Your Food Plots:
The First and Most Important Step
By Rod Ellwanger

Soil testing your food plots is one of the most important things that you can do to ensure a successful plot. The results obtained from the Soil Test Report will tell you the pH (level of soil acidity), organic matter content, and phosphorus and potassium levels in the soil of your plot field. This valuable information will help you decide what to apply for lime, fertilizer and which crops to plant in each particular field based on pH—some crops are more pH-sensitive than others. Most soils in forested areas where food plots are created will be somewhat acidic and have a low pH number.

A soil pH of 7.0 is considered neutral and is ideal for growing many agricultural crops such as alfalfa. However, a soil pH of 6.0 is considered adequate for growing most food plot crops. A soil with a pH of 5.0 is 10 times more acidic than a soil with a pH of 6.0, and many of the nutrients in the soil will not be available to the crops because they will be tied up in the soil solution. Raising the soil pH makes the soil less acidic, making the soil nutrients more available to a growing crop. Other benefits include improved bacterial activity and nitrogen fixation by legumes along with improved physical condition of the soil. The pH can be raised by mixing lime into the soil.

An illustration of a low pH soil environment would be if you were sitting at a table heaped with food, but were unable to eat because your jaw was wired shut. There is plenty of food in front of you, but you are unable to consume it. Now if someone would unwire your jaw part way you would be able to take in some of the food, and the more it was unwired the more food you could eat. In the same way adding lime to the soil raises the soil pH releasing more nutrients from the soil solution so the crop can eat and grow.

Spreading lime on the surface of your plots and tilling it in is the best way to correct a low pH field. Whether the lime is referred to as aglime, barn lime, high-calcium, pel-lime or something else, there is little difference in the ability of the liming material to correct the pH of the soil. What can make a difference is the particle size, which relates to how fast the material will be dissolved in the soil solution. A coarse lime (60-69) will take longer to have the same effect as a fine aglime (80-89). Pel-lime is a fine lime that has been pelleted and will perform equal to a fine aglime. As a rule the lime you apply will take 6-24 months to dissolve and and neutralize soil acidity. A common misunderstanding when liming is that the lime spread on the surface will be carried down through the top 6-7 inches of topsoil by rain water. This is not the case. Lime in any form will move very little in the soil profile and must be tilled and mixed with the topsoil to have the desired effect. Does this mean that lime applied to the surface and not mixed in is wasted? No, it just means you won’t see much neutralizing effect until the soil is tilled mixing the top layer with lime throughout the 6-7 inches of topsoil.

The best way to determine the pH of your soil is to take a soil sample from your plot field and send the sample to a testing lab for analysis. There are many reputable labs that provide this service at a minimal cost. Your local farm supply or hardware store can provide you with options in your area. I would not recommend using electronic pH probes or small home pH testing kits. These are very quick and easy, but the accuracy is questionable at best, and from my experience, often very inaccurate. After sending your sample to a testing lab, you will receive a Soil Test Report in about two weeks. In addition to a liming recommendation, the report will provide fertilizer requirements based on the crops selected to be grown. Apply the recommended amount of lime, or as much as you can afford or physically apply. Do not apply a portion of the recommended amount of lime in the spring and retest the soil in the fall to see how much effect was achieved. The undissolved lime in the soil can alter the test and probably give a false pH reading much higher than it really is. It is best to apply somewhere near the recommended rate of lime, then wait 2-3 years to retest the soil. Applying more than the recommended amount of lime to a low pH soil will usually not cause any problems and may be more cost effective especially if you can get a truck to come in and spread a load of bulk lime rather than purchasing bags and spreading it yourself.