The automatic soil auger probes, was told they discard the top 3" of the sample  as not a representative test . We only have 6-8" of topsoil over clay.

Explanation given was they want a soil test of the root zone and top 3" shows less nutrients than what is available to the crop.Thoughts?

Any good videos on proper way to take a soil test?

They use a sampler similar to this  https://wintexagro.com/products/wintex-1000/