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/

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Find out more about soil tests with ATC at https://www.asianturfgrass.com/project/soil-tests/