Soil Moisture Sensors

What is the difference in soil moisture sensors and how do I get the best bang for my buck?
Below is a brief explanation of the main types of soil moisture sensors and where they are suited.

Capacitance
Capacitance sensors means the sensor sends out an electrical current from one end towards a receiving end. Water collects and stores current a lot better than air and soil therefore the amount of water in the soil can be determined. Because this method relies on the electrical conductivity of water the presence of ions for instance salt (soils closer to the sea) can give inaccurate results. These sensors may need calibrating to adjust their outputs according to a sensor of known accuracy.
The majority of the sensors on the market will be capacitance sensors, they are very common and are good because they are easy to install, read and are reasonably priced. However it is important to remember that not all of these sensors are equal ask what the warranty is on the probe, do a quick review online to try and access credibility and ask to have the display that you will read off set up so that you know the units being reported and your limits (target and trigger point).

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