How can we test the soil using sensors?

Airflow sensors were used to measure soil air permeability on the go. The pressure required to squeeze a given volume of air into the soil at fixed depth was compared to several soil properties. Experiments showed potential for distinguishing between various soil types, moisture levels, and soil structure/compaction. https://cropwatch.unl.edu/ssm/sensing https://www.quora.com/Are-there-any-sensors-available-for-checking-nutrient-levels-in-the-soil