HI 993310 measures both the soil conductivity in EC (mS/cm) as well as salt activity in grams per liter. The different scales can be selected through two keys on the front mask and two separate LEDs indicate which parameter is being tested. In addition, HI 993310 is equipped with an alarm LED that automatically turns on if the soil is too dry, or nutritive substances such as potassium or nitrogen are lacking. In the former case, demineralized water is to be added to the soil prior to proceeding with further tests. Direct soil measurement is facilitated by the small diameter, stainless steel, pointed HI 76305 probe. Once inserted into the ground, the user simply waits until the meter displays the value read by the auger-like probe.