What a Direct Soil EC Meter Saves You
The old routine was a slurry. Take a sample, mix it with distilled water at a set ratio, wait, filter, then read the extract. It works, and it takes long enough that most people skip it. The HI98331 puts a stainless steel penetration probe into the substrate and reads it where it sits. Range runs 0 to 4000 uS/cm, resolution 1 uS/cm. One button, one-point calibration, done automatically against a 1413 uS/cm standard.
Bulk EC, and What a Soil Conductivity Tester Is Really Telling You
This is worth being precise about. What comes back is bulk EC. That is the conductivity of everything in the sample together, meaning the soil particles, the water in the pores and the air between them. It is not the same number as a saturated paste extract, and comparing the two directly will mislead you. Bulk EC is still the reading you want for tracking, because it moves when your feed moves. Knowing water content lets you calculate pore water conductivity from it. A soil conductivity tester also needs moist soil to read at all, since dry substrate has nothing conductive to bridge the pins. Rinse the probe with deionized water and dry it before each reading. Make the hole with an auger or a ruler so depth stays consistent between spots. Temperature compensation is automatic on a fixed 2% per degree coefficient, using the integrated sensor.
Key Features
- Reads straight out of the substrate: The stainless penetration probe removes the slurry step, which is the step most people skip.
- 0 to 4000 uS/cm range: Resolution of 1 uS/cm, with accuracy of +/- 50 uS/cm across the lower half of the scale.
- Automatic temperature compensation: An integrated sensor corrects every reading on a fixed 2% per degree coefficient.
- One-point automatic calibration: Recognises the 1413 uS/cm standard on its own, on a single button.
- 114 mm penetration electrode: Long enough to reach past the surface layer into the root zone where the number matters.
- Roughly 100 hours on a CR2032: With a storage and protection sleeve for the probe between readings.
Technical Specifications
| Specification | Value |
|---|---|
| Model | Hanna GroLine HI98331 |
| Conductivity Range | 0 to 4000 uS/cm; 0.00 to 4.00 mS/cm (dS/m) |
| Conductivity Resolution | 1 uS/cm; 0.01 mS/cm |
| Conductivity Accuracy | +/- 50 uS/cm (0-2000), +/- 300 uS/cm (2000-4000) |
| Temperature Range | 0.0 to 50.0 C |
| Temperature Resolution | 0.1 C |
| Temperature Accuracy | +/- 1 C |
| Calibration | Automatic one-point at 1.41 mS/cm |
| Temperature Compensation | Automatic, fixed 2% per C coefficient |
| Electrode | 114 mm (4.5 in) stainless steel penetration probe |
| Battery | CR2032 Li-ion, approx 100 hours continuous |
| Dimensions | 50 x 196 x 21 mm (2.0 x 7.7 x 0.9 in) |
| Weight | 74 g (2.4 oz) |
| Environment | 0 to 50 C (32 to 122 F), RH max 95% non-condensing |
| Included | Penetration probe, CR2032 battery, storage sleeve, manual, quality certificate |
| Warranty | 1 year |