The take-home message is yes, we’ve been doing it wrong. Composite sampling is not ideal. Doing so is likely to overestimate the nutrients in the soil, which leads to fertilizer recommendations that are slightly too low.
It’s not a huge error for most turfgrass sites, as far as I can estimate. But there are also exciting opportunities to improve fertilizer recommendations with more effective sampling procedures. Stay tuned.
For more about soil testing and nutrients in turfgrass soils, see: