By Jon Cooner
When it comes to planting food plots, no other step offers the greatest potential to ensure optimum results and help save money as testing your soil through a qualified soil-testing laboratory. It’s simple and inexpensive, and it provides information that’s critical to food plot success. To get the most for your money, however, be sure that you prepare and submit the soil sample the right way.
SOIL TEST KIT
If you are going to spend your hard-earned money on something to test your soil with, be sure you get the most bang for your buck. Use a soil test kit that actually sends soil off to a qualified soil-testing lab for analysis, not a do-it-yourself probe or slurry kit. Only a qualified soil-testing lab can offer truly consistent results, give you exact readings of the soil’s soil pH and nutrient content and make precise recommendations as to whether you need to add lime, how much lime to add and what blend and amount of fertilizer to use. High quality soil test kits are available from the Whitetail Institute and most county agents, farm-supply stores and agricultural universities.
SOIL SAMPLING EQUIPMENT
The Whitetail Institute soil test kit and most other high-quality laboratory soil test kits come with instructions that are very easy to follow. Here are a few items that will help you prepare your sample and paperwork quickly and properly.
• Laboratory soil test kit (available from the Whitetail Institute, and most farm supply stores, county agents and agricultural universities)
• A clean one-gallon bucket
• Small clean shovel or clean soil test probe*
*Soil test probes are long cylinders open on the bottom end and with one side scalloped out. The cylinders are mounted to a handle. By pushing down on the handle, the cylinder is pushed down into the seedbed and fills with a column of soil as deep as the probe is pushed. When the probe is withdrawn, the scallop on its side allows access for the soil to be pushed out of the probe and into a bucket. Soil test probes can be purchased from a wide variety of sources. They can also be made out of sturdy one-inch PVC pipe.
HOW TO PREPARE AND SUBMIT YOUR SOIL
SAMPLE TO THE LABORATORY
Step 1: If you are preparing the site to plant (as opposed to maintaining an existing forage in it), select the forage you intend to plant before testing the soil, if possible. Not all forages need the same nutrients. If the lab is to provide fertilizer recommendations that are specifically tailored for your specific needs in that plot, you’ll need to let the lab know what forage you will be planting there. That way, the lab will be able to precisely tailor its recommendations for that site’s specific soil characteristics and that particular forage.
Step 2: Commit to following the instructions that came with the soil test kit. Most high-quality soil test kits come with step-bystep instructions that are short and easy to follow. Be sure you follow them exactly, because the quality of your efforts in preparing the sample is very important to how accurate the tests results can be. So take care to prepare a high-quality sample for testing.
Step3: Make sure your equipment is clean and free of rust or other foreign matter before you take your soil samples, and be sure you thoroughly clean it before you move on to the next site. Remove any foreign matter in your bucket, shovel or probe, or any other equipment involved in collecting and preparing the sample for testing including soil remaining on the equipment from plots you sampled earlier which can contaminate the samples you’re about to take.
Step 4: Pull representative plugs of soil, each from three to six inches deep, from many areas of the site, and place all of the plugs together in the bucket. Keep in mind that you’ll be sending only about a cup of soil to the lab for testing, and that sample must represent all the soil in the plot. That’s why you should take as many plugs from as many areas of the plot as your common sense tells you is necessary for the sample to contain a good representation of the soils over the entire seedbed. If you aren’t sure you have taken enough plugs from different areas of the plot yet, keep taking more plugs until you are sure. That way you’ll know that the lab will be able to give you the most beneficial results.
Step 5: After you have put all the samples into the bucket, stir all the soil in the bucket together thoroughly, and remove rocks, plant matter, etc. Fill the testing container with a portion of the thoroughly mixed soil from the bucket.
Step 6: Fill out all the information requested on the soil sample pouch and submission form. You’ll need to provide information you’d expect, such as your name, address and the name of the plot the soil sample came from. And again, you’ll also need to let the lab know whether you will be planting a forage or maintaining an existing forage in the site and, for best results, what that forage is. The Whitetail Institute soil test kit makes it easy for you to specify both. You just check the appropriate blocks on the submission sheet. If you forget to specify those things, though, or if you perform a soil test before you decide what you’re going to plant, don’t worry. As always, the Whitetail Institute’s highly trained in-house consultants are standing by to help you with any need, including adjusting your soil test report for you right over the phone — for free.
WHEN TO TAKE YOUR SOIL TEST SAMPLES
There’s no way to say exactly how far in advance of planting you should test your soil because situations differ. Allow as much time as you can though. Also, if you are planning to do any sort of deep tillage that would move soil vertically within the seedbed, try to wait to collect the sample until after that has been done. Let’s look at each of these in turn.
HOW LONG BEFORE PLANTING TO TEST
If possible, it is advisable to test your soil at least several months in advance of planting. Fallow soils are most commonly in an acidic state, meaning that soil pH is less than optimum (below 6.5 to 7.5). In such cases, the soil test report from the lab will give you a precise recommendation as to whether you need to add lime and, if so, how much. Any lime you add to raise soil pH during seedbed preparation should be incorporated into the seedbed by disking or tilling. Lime takes time to complete its job of raising soil pH. Usually several months is plenty of time. That’s why it’s a good idea to test your soil several months in advance of planting if possible, so that any lime you need to add based on the report will have more time to work.
If you are planning deep tillage as part of the seedbed preparation process, consider whether the form of tillage you anticipate will move soil vertically within the seedbed. If the type of deep til-lage you plan will move lower levels of soil in the seedbed up (and the surface down lower into the seedbed), it is best to take your soil samples after the deep tillage has been done.
A good example is the difference in the way chisel plows and moldboard plows work the soil. A chisel plow generally breaks up the ground but does not move soil vertically much. Moldboard plows, on the other hand, lift the top six or more inches of the seedbed as a column, and flip it upside down in an adjacent furrow. If you soil-test before deep tillage with a moldboard plow, you might be testing soil that won’t be near the surface later when you plant. (For more information on how chisel plows and moldboard plows move soil within the seedbed, see “Turning Dirt: Plows for Food-Plot Tractors,” by Mark Trudeau, which is available on-line at: www.whitetailinstitute.com/info/news/Turning_Dirt2.pdf.)
DO AT LEAST ONE SOIL TEST PER SITE
For best results, be sure to perform a soil test of every site you intend to plant or maintain. Even if you have two food plots that are very close to each other and have soils that appear very similar, the soil pH and soil nutrient levels can differ substantially from one site to the next, even when the soils appear identical to the eye.
If we assume that hunting food plots generally run from about 4,500 square feet (1/10h acre) up to about two to three acres, one soil test per site should be sufficient — if you prepare the sample in the manner described.
Ordinarily, it’s not necessary to do more than one test per site. An exception, though, is if you see one type of soil in one part of the plot but a different type in another. An example would be one food plot site that includes a sandier hillside and a flat bottom with dark, rich soil. In such cases, it can be a good idea to do a separate soil test for each area, one test just of the sandier hillside and a second test just of the bottomland.
If you would like additional information on soil testing or would like to order a high-quality Whitetail Institute soil test kit, our consultants are standing by to assist you at (800) 688-3030.