The Smart Way to Measure Soil Compaction Soil Works LLC 

We recommend using both the penetrometer and an electrical conductivity meter to establish baselines as well as monitoring in season trends in soil health. The electrical conductivity, in particular, yields insights into in-season soil microbial activity, which can be useful for managing in-season nutrient availability. Typically you will you see a change in soil EC one to two weeks before diseases and/or pests reach critical thresholds on the plant. Abiotic and biotic stressors can cause the soil microbial communities to work harder creating more demand for the plants energy (sugar) which stresses the plant. If the soil's demand as so great that the plants immunity is compromised, the plant cannot fight off disease and/or pest pressure. By monitoring and measuring in-season EC you can often prevent these pest pressures with properly timed bio-stimulants and inoculates before you have to react with foliar sprays and/or pesticides. Thanks for the great questions!