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Test Your Soil for Better Food Plot Growth

FOOD PLOTS | JUNE 01, 2018

Once you’ve decided where to put your food plots, soil samples should be taken. These should come from each area to be planted, and sent to a soil-testing lab for analysis. A soil test determines how much lime and fertilizer is needed to grow a specific crop to its maximum potential. Soil tests should be done at least every two years since tremendous amounts of nutrients are removed from the soil each year by growing plants and leaching due to rain.

Testing Your Soil

Taking a soil sample is an easy task. The only things you need are a shovel or soil probe, a clean bucket and boxes or bags to ship the samples. Boxes often are available at no cost from your County Extension Office or at many feed and seed stores. Take the sample using the shovel or soil probe. The sample should come from the top six inches of soil in each food plot. This is where the roots of the crops will grow. Make sure the sample is free of grass and other vegetation. This added material affects the test results.

On small food plots, one-half acre or less, it is okay to take the sample from one spot in the food plot. Place approximately 1-1/2 to 2 cups of the soil in a container suitable for shipping to the soil-testing lab. Label the sample with the name of the food plot and the crop to be planted. If more than one food plot is tested and their locations or names are not written on the samples, it will be impossible to match test results with the source food plot. Different crops have different pH and nutrient requirements. Make sure the crops to be planted are indicated on the container so the lab can make the correct recommendations.

Most soil testing labs charge a small fee, usually less than $10 per sample, for their services, but some of the larger feed and seed stores provide free or reduced cost soil tests to their customers. Regardless of the costs, taking soil samples and getting soil tests for each food plot are two of the most cost efficient things that can be done prior to planting. Knowing exactly how much lime and fertilizer to apply maximizes the productivity of each food plot, which saves money in the long run.

Interpreting Soil Test Results

Once soil test results are received, it may be necessary to get some assistance with interpreting the recommendations. Most test results give recommendations as tons of limestone per acre and pounds of nitrogen (N), phosphorous (P) and potash (K) per acre. For many people, the confusion comes from the recommendations and the way fertilizers are labeled. Commercial fertilizers are labeled to indicate the percentage of N (first number), P (second number), and K (third number) in each bag of fertilizer. A 50 lb. bag of 13-13-13 fertilizer contains 6.5 lbs. of N, 6.5 lbs. of P, and 6.5 lbs. of K. On the other hand, soil test results give recommendations as pounds per acre. Farmers' co-ops and most seed and fertilizer dealers can provide further assistance with interpretation of soil test results.

Lime and Fertilizer

To get the most production from a crop it is very important to follow the lime and fertilizer recommendations exactly. Skimping on lime and fertilizer results in wasted money and crops that do not produce to their potential. Of the two, the most benefit is gained from adding the recommended amount of lime to raise the soil pH to the recommended level. Having the soil pH in the optimum 6.5 to 7.0 range enables plants to utilize a much larger percentage of the available soil nutrients than when the soil pH is more acidic or basic.

Apply lime well in advance of planting. Apply the lime three to six months ahead of time to give the lime adequate time to affect the soil's chemistry and increase the soil pH. The limestone can be applied to either plowed or unplowed food plots, but plowing it in after application enables it to work faster. Other sources of lime, such as hydrated lime or pelletized lime, are also available for correcting soil pH.

Apply fertilizer at the time of planting. Fertilizer is easily applied with a spin-type seed/fertilizer spreader. Using the spin-type spreader allows better control of fertilizer distribution than the buggy and generally works best on average-sized food plots.

Plow, disc or till the fertilizer into the soil before applying the seed for best results. Some components of fertilizer, for example phosphorous, are not mobile in the soil. They need to be distributed in the root region of the soil, the top four to six inches, to improve utilization by the plants. Allowing the fertilizer to remain on the soil surface leaves most of these immobile components out of reach of the plant roots. Plowing, discing or tilling too deep also puts much of the fertilizer out of the plant’s reach.

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