Soil P, pH, and salinity are a few things that likely vary by depth in your rootzone. I've started recommending that 20% of putting greens tested be done with a sample divided at the 5 cm depth. Send the lab a 0-5 cm and 5-10 cm depth sample from that green, rather than the standard 0-10 cm depth sample. I discussed this blog post: https://www.asianturfgrass.com/post/reconstructing-soil-p-from-disassembled-soil-samples/ The MLSN page on the ATC site: https://www.asianturfgrass.com/mlsn/ Read more about all kinds of turfgrass topics at https://www.asianturfgrass.com/Get ATC newsletters at https://www.asianturfgrass.com/newsletter/Turfgrass information and decision-making tools at https://www.paceturf.org/PACE Turf YouTube channel at https://www.youtube.com/user/paceturfATC's YouTube channel at https://www.youtube.com/asianturfgrasscenter