Reference Ranges: A Novel Interpretation of Turfgrass Nutrient Values

Core Ideas: Plant tissue tests are interpreted using yield as a metric. Turfgrass value is commonly measured using quality. Reference ranges identify “normal” nutrient ranges by using turf quality as a metric. Reference ranges should be considered as an alternative tissue test interpretation. Tissue testing is a common practice in turfgrass management and is intended to guide nutrient applications. However, standard interpretations are a product of agricultural cropping systems and use yield as the primary metric. Yield is often of little importance in turfgrass systems and, thus, traditional test interpretations may be of little value. Reference ranges interpret test results by first defining a ‘normal’ population followed by analysis and determination of the 95% confidence interval for each nutrient. Moreover, reference ranges can be determined for cultivar, season, and age-specific populations, which would result in a more precise interpretation and nutrient recommendation for turf managers. Because reference ranges use the accepted turf quality metric, reference ranges should be considered as an alternate option to traditional turfgrass tissue test interpretations.