Soil-testing laboratories use standards and protocols to determine soil nutrient availability; however, standards, methods, and units of measure might vary from one lab to another. By knowing the various methods and units of measure used, you can verify that you are receiving the proper analysis.
Units of Measure
Phosphorus Extraction Methods
Various methods have been developed to determine the level of plant-available phosphorus in the sample. Each method generates different results that might equate to similar levels of fertility.
Comparison of Phosphorus Relative Levels by Extraction Method - Iowa
Potassium Prep and Extraction Methods
Note: Ammonium Acetate and Mehlich 3 Potassium extractions generate nearly identical results.
Comparison of Potassium Relative Levels by Preparation Method – Iowa
When working with soil sample test results, notice the methods the laboratory uses to accurately understand the level of fertility in the sample.
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