A plain-English guide to moisture, pH, conductivity, temperature and N-P-K — and the limits of each.
TerraProbe Portable records seven indicators. Here is what each is good for, and where it stops.
MOISTURE
Useful for judging whether two readings are comparable at all. Also a reasonable proxy for infiltration and cover effects over time at the same point.
pH
A screening value. It flags a paddock worth investigating, but lime decisions need laboratory pH in both water and CaCl₂, exchangeable aluminium and buffering capacity.
ELECTRICAL CONDUCTIVITY
Moves with salts and with moisture. A jump against the paddock's own baseline is worth rechecking; an absolute number in isolation is not a salinity diagnosis.
TEMPERATURE
Context for everything else, and useful for timing sowing decisions you were already making.
NITROGEN, PHOSPHORUS, POTASSIUM
The most commonly over-read of the seven. Portable N-P-K values are indicative. They help you decide where to send a laboratory sample. They cannot support a fertiliser rate, and anyone telling you otherwise is selling something.
The value of the set is not any single number. It is seven numbers at the same point, on a known date, that you can compare to the same seven numbers next season.
MOISTURE
Useful for judging whether two readings are comparable at all. Also a reasonable proxy for infiltration and cover effects over time at the same point.
pH
A screening value. It flags a paddock worth investigating, but lime decisions need laboratory pH in both water and CaCl₂, exchangeable aluminium and buffering capacity.
ELECTRICAL CONDUCTIVITY
Moves with salts and with moisture. A jump against the paddock's own baseline is worth rechecking; an absolute number in isolation is not a salinity diagnosis.
TEMPERATURE
Context for everything else, and useful for timing sowing decisions you were already making.
NITROGEN, PHOSPHORUS, POTASSIUM
The most commonly over-read of the seven. Portable N-P-K values are indicative. They help you decide where to send a laboratory sample. They cannot support a fertiliser rate, and anyone telling you otherwise is selling something.
The value of the set is not any single number. It is seven numbers at the same point, on a known date, that you can compare to the same seven numbers next season.
A screening reading is a starting point
TerraTactics readings help you target follow-up sampling. Confirm anything material with
accredited laboratory testing and a qualified local agronomist.
Published 16 July 2026 by David Gilbert
