Conductivity (also called electrical conductivity or EC for short) is a measure of a substances ability to conduct an electrical current and this can be measured using a conductivity meter. In the farming and the agriculture industry, conductivity can be used as an indicator of overall soil nutrient levels.
Many factors will affect the soil conductivity, including temperature, fertiliser use, salinity, irrigation and temperature. To read our post on what conductivity is and its relationship with other measurements (TDS, salinity and resistivity) click here. There are two main methods of testing soil conductivity- mixing the soil with water to form a slurry or direct soil testing. Below we list some of our product offering which would be suitable for this application.
Hi-98331, Groline direct soil conductivity tester by Hanna Instruments
This handheld meter has been designed with direct soil testing in mind however it can also be used for measuring soil slurry. It features a stainless steel penetration probe (it is of a four ring design which is great for testing over large conductivity ranges) and automatic temperature compensation. It has a large simple display combined with one button interface which was made with the non-specialist in mind. Calibration: This unit uses a one point calibration using 1413us/cm calibrant. Buy the meter here.
Conductivity (Range: 0.00 to 4.00 mS/cm, resolution: 0.01 mS/cm )
Temperature (Range: 0.0 to 50.0°C, resolution: 0.1°C)
Agri-Meter by Myron L
It is designed specifically for use in the farming and agriculture industry. It can be used for water, soil and fertiliser testing and is even suitable for low conductivity boiler water. When testing soil, this meter requires the soil to be made into a slurry prior to testing; Myron L recommends a 2:1 mix of water to soil for most applications. This meter is analogue and re-calibration can be performed by finger adjustment of the slope. It has automatic temperature compensation for conductivity for samples up to 25°C. Calibration: The conductivity and pH parameters will need calibration. pH is done with a three point calibration at pH 4, 7, 10 and conductivity has a one point calibration at 3.9 millimhos. Buy the Agri-meter here.
Conductivity (Range: 0-5millimhos, accuracy: ±2% of full scale
pH (Range: 2-12, accuracy: ±0.2 pH units
Tips for testing soil conductivity
When soil testing, avoid the upper half inch or so as salts tend to accumulate there due to surface water evaporation, this will give a higher conductivity reading.
Mix into slurry with distilled or deionised water. It is not necessary to measure the conductivity of this as it will not be high enough to have a large effect on the mixtures conductivity. If you use tap water however this step will need to be taken.
Take samples from all across the growing area. Conductivity can differ greatly from the plant roots area compared with slightly further away. This method helps to give a complete overview of the EC readings from your whole growing area.
Our range of conductivity meters are available here. If you have any questions relating to choosing a conductivity meter/probe for testing your soil, please ask using the contact form below. Alternatively you can email us at firstname.lastname@example.org or give us a ring on +44 (0)1954 233120.