Correlation and calibration of Mehlich‐3 sulfur for Kentucky bluegrass

Abstract Sulfur (S) is a crucial macronutrient for turfgrass growth, and declining atmospheric deposition has increased the risk of S deficiency. Reliable Mehlich‐3 soil test interpretations for S are lacking for turfgrass. This study aimed to correlate and calibrate Mehlich‐3 S with the visual quality and yield of Kentucky bluegrass ( Poa pratensis L.) through four field trials conducted over 2 years in Lexington, KY. Results indicated that critical Mehlich‐3 soil S concentrations for acceptable turfgrass quality ranged from 3.1 to 5.7 mg kg −1 varying by seasons, and for maximum yield ranged from 6.1 to 8.1 mg kg −1 . Applying S at a rate of 8.2 kg ha −1 alleviated visual S deficiency symptoms and resulted in acceptable turfgrass quality when soil S was limiting. Tissue S content was more variable than extractable soil S but tissue S also correlated well with turfgrass response. When antecedent Mehlich‐3 S levels were ≥8.4 mg kg −1 , S application did not improve turfgrass parameters. This research demonstrates the Mehlich‐3 extract can be used to predict soil S deficiencies for Kentucky bluegrass, with concentrations ≤5.7 mg kg −1 suggesting a high risk of turfgrass quality reduction, and soil with >8.4 mg kg −1 unlikely to be associated with S‐deficient Kentucky bluegrass.