Opting Only For Traditional Tests Can Hurt You Later

exchangeable available table

A complete test for your turfgrass soils includes two tests, the exchangeable nutrient test and the paste extract test (soluble salts). Only opting for the exchangeable nutrient test or the traditional soil test, as it is known, only tells you half of your turfgrass’s story.

The information on traditional soil tests gives you the “total bank” of nutrients in the soil along with some of the chemistry data (ph, CEC, Ec, and OM). It’s what your plant is growing in and can be challenging to change. Most soil recommendations come from exchangeable data deficiencies, and many of the suggestions will be granular as we need higher quantities of those nutrients to address the shortcomings. Higher concentrated liquids are also recommended for these deficiencies.

While knowing what the plant is growing in is essential, it’s just as important to know what nutrients the plant sees at certain times.  This is where the paste extract test comes in and tells the rest of the story. Available nutrients are derived from a paste extract test, a measure of all the nutrients and salts in the soil solution at a particular time or what’s immediately available to the plant.

So, without a paste extract test, we can’t infer what nutrients are tied up or unavailable. For example, phosphorus can show up at an optimal level on the exchangeable data side but be less than optimal on the available nutrients side. By comparing the two, we can detect the possible tie-up of phosphorus with cations. Often we’ll see that P is very low in availability, and it is also rendering cations like Mn, Fe, and Ca unavailable.  But without the comparison, we would not know, possibly resulting in the plant developing nutrient issues.

Where can you find a business providing Exchangeable and Paste Extract tests? Foliar-Pak. Foliar-Pak’s Soil Solver is a detailed report and a great tool to help you identify exchangeable and available data and pH, CEC, EC, and OM issues. This information is graphed, recorded, and comes on one sheet, which makes it very easy to read.

Foliar-Pak’s experts will also evaluate the information from Soil Solver and provide recommendations for soil applications to address long-term deficiencies and foliar applications to provide relief from immediate deficiencies. The recommended product mixes are based on actual needs defined by Soil Solver, which reduce unnecessary inputs and improve application efficiency.

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About the Author Curt Geron

I am a Foliar-Pak territory manager and the lead for Foliar-Pak product development. I’ve been with EnP Investments, the manufacturer of Foliar-Pak, for almost nine years. In addition to my responsibilities at EnP, I’ve worked as golf course superintendent and owner/operator of a lawn care company. With B.S. and M.S. degrees in Agronomy from The Ohio State University, I developed a passion for plant science and fertility. If you would like to learn more about the science behind our products or discuss practical applications for using our products to improve turfgrass and plant health, let’s connect.

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