Kansas State University just released this video on how our soil testing lab works. I’m sure it is a similar process at all soil testing labs, but I thought you might find it interesting. There are quite a few people working in the lab, so for a very small investment in your local university soil testing lab (ours is $6 to $10.50 per sample depending on what you want to know), you can get excellent results very quickly.
The soil testing lab can also do analyses on water samples, plant tissue and soil-less media. For more information, contact your local university soil testing lab.