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Benefits of Fall Soil Sampling

October 26, 2018
Soil testing

This fall’s mostly mild weather has many farmer’s finishing field work ahead of schedule. Before we call it a season however, there is one last very important thing you can do to prep for next season: getting your soils tested. Right now is still a great time for taking soil samples, there is still moisture in the soft ground, which makes sampling easier, and temperatures are still fairly mild, making the procedure a less miserable experience. Sampling in the fall also allows an adequate amount of time to receive results and plan accordingly for the 2019 season.

There is no greater resource to a farmer than their soil. Knowing the properties of that soil, and then making the appropriate amendments through fertilizer and pH adjustments can have a huge impact on crop yield, while being very cost effective. Soil samples allow farmers to take a look at their soil health, mainly by capturing their current Nitrogen (N), Phosphorous (P), and potassium (K) levels, as well the soil’s pH, which tells us how available the nutrients are to the plants as well as essential microorganism activity. Soil tests will also give us the soils Cation Exchange Capacity (CEC), which tells us the soils ability to attract and retain positively charged cations, or nutrients, such as potassium, magnesium, and ammonium. Soils with a higher CEC, usually soils with high organic matter, will hold on to these nutrients, while soils with low CEC will have more nutrients leach through the root zone.

Purdue recommends soil sampling approximately every 3 years depending on the fields CEC, cropping system, and past soil test results. A soil sample should not represent more than about 15 acres and should comprise at least 15 soil cores, while avoiding field abnormalities such as: low spots, field edges, hill tops, or high traffic areas. Fields with frequent changes in soil texture or topography should be broken down by area allowing for variable fertilizer applications, which save money and maximize good and poor spots of a field. For crop nutrient analysis 0 to 8 inch soil cores are standard. Cores of an area should be mixed together well, dried down, and then placed in a clearly labeled bag, which can often be provided by the lab you intend to send the soil to. Remember to have the labeled soil bag matchup with a field map or sketch so there is no confusion over results once they are obtained. Soil maps of your field can be found at: http://websoilsurvey.sc.egov.usda.gov For a list of certified labs in the area visit: https://ag.purdue.edu/agry/extension/Pages/soil_testing.aspx

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