The Importance Of The Conductivity Meter To The Agricultural Industry

Electrical conductivity is extensively used and measured in many different sciences and industries. None more so than in the agricultural industry where the conductivity meter is regularly used to measure the components of water, soils and fertilisers. Meters are normally handheld although for more exacting purposes, desk top varieties are often used for in-depth analysis. Measuring conductivity gives operatives an idea of the salt content of any water or soil sample as salt is conductive, meaning that the higher the conductivity the higher the salt content of a particular sample will be.

By knowing the salt content of the soil, water and fertilisers it is possible for agricultural investigators to discover why their crops are failing, or give an idea of ways to improve productivity. While physical indicators such as burnt edges of the leaves gives an idea that the salt content may be too high, only a conductivity meter will be able to give exact results of the amount of salt in a sample.

Conductivity meters do however have limitations for this purpose; while it is possible to find the overall salt content, it is difficult to find the precise salts which are causing the problems. This is where handheld meters are usually abandoned for the more precise desk top models. This type of meter allows for detailed laboratory testing of samples and gives a far more precise read out containing information on the different salts in a sample. Most who work in agriculture agree that by taking as many samples from all over the growing area gives the best idea of what may be causing problems to plants.

In terms of units of measurement conductivity is normally measured in Deci-Siemens (dS/m). At times though, for more precise measurement micro and multi siemens are used, all are combined with a unit of length giving conductivity a physical property. Ohms are used in the electrical industry to measure resistance, conductivity is simply the resistance combined with the length of an object and is sometimes referred to as resistivity.

Temperature can affect the read outs on a meter however. Resistance relies upon the movement of ions in a substance for measurement and if these are agitated by heat naturally the results will be affected. Most estimates place the effects of temperature on conductivity at around two or three percent per degree in Celsius. Understandably it is vital when taking readings to note the temperature so it can be accounted for when compiling results. Ideally a temperature of around twenty five degrees is the temperature to take the readings.

It is always important to calibrate a conductivity meter before each use. If this is not done results can be skewed. To calibrate a device the operator must take a sample of known salinity (salt content) and to take readings from this sample. By adjusting the device so it is reading this sample accurately you know that the meter will give you accurate readings once you are out in the field. Most meters have a screw at the back that can be turned in order to calibrate the device making the process simple and effective.

As previously stated the importance of the conductivity meter to the agricultural industry is immense. Without it, finding the qualities of soil would be more guess work than science resulting in poorer crops. The device has revolutionised the way farming is conducted making it a far more logical and scientific process, bringing it into the modern age with a bang.

Industry expert Thomas Pretty looks into the importance of the conductivity meter in science and agriculture.

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