potassium, Mehlich-3, ammonium Acetate, correlation
The K-State Research and Extension Soil Testing Laboratory has been using Mehlich-3 soil test procedures for phosphorus (P) extraction, and ammonium acetate extraction for potassium (K). Previous research in other states has shown a strong correlation between these two tests for K, but data correlating the two in Kansas soils have been limited. A study was performed on soils from across the state to investigate the relationship between these two methods. A strong positive correlation was observed (r = 0.99) across the wide range of soil types, pH, and fertility conditions represented in the sample set. Linear regression suggests a near 1:1 relationship and strong fit between Mehlich-3 and ammonium acetate extractable K (slope = 0.97, R2 = 0.98). Based on these results the Mehlich-3 procedure for soil K analysis is a suitable for Kansas soils.
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Rutter, B. and Ruiz Diaz, D. A.
"Correlation Between Mehlich-3 and Ammonium Acetate Extractable Potassium in Kansas Soils,"
Kansas Agricultural Experiment Station Research Reports: