Well, the answer is a multitude of things!
For one, soil scientists measure soil nutrient levels to discover the “goldilocks” level of fertilizer application for crops like cotton, corn, and wheat, which is important for sustaining life on earth and reducing pollution from excess fertilizers!
Here, David Weindorf of Texas Tech demonstrates the use of a new tool – portable X-ray fluorescence spectrometer, which gives rapid and accurate results about what elements are found in soil. Pretty sweet stuff.
Planetary Soils 