Abstract Soil testing provides golf course superintendents with the information needed to apply fertilizers at optimal rates, thereby avoiding nutrient deficiencies and unnecessary applications. However, nutrient rate recommendations vary depending on how soil test results are interpreted. Two approaches to interpreting soil test results are the Sufficiency Level of Available Nutrients (SLAN) and the Minimum Levels for Sustainable Nutrition (MLSN). Although these approaches have been compared on putting greens outside the United States, they have not yet been compared within the United States. Therefore, the objective of this study was to compare the effects of SLAN and MLSN nutrient recommendations on a ‘Penn A‐4’ creeping bentgrass research putting green ( Agrostis stolonifera L.) grown on a United States Golf Association–specification root zone in Michigan. The study was conducted at the Hancock Turfgrass Research Center in East Lansing, MI, from 2019 to 2021. The experimental design was a split‐plot with two factors and three replications. The whole plot included three levels: SLAN, MLSN, and a nitrogen‐fertilized control treatment. The subplot included two levels: trafficked and non‐trafficked. Soil samples were collected in the spring and fall to a depth of 6 in. Turfgrass quality and health were measured monthly. Both approaches recommended a similar phosphorus application rate. However, MLSN recommended 200% less potassium than SLAN while maintaining comparable turfgrass quality under both trafficked and non‐trafficked conditions.
Guevara et al. (Tue,) studied this question.
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