Wikipedia has a great article on soil moisture sensors, but it focuses on commercial/farming/large-scale settings. I'm investigating options for consumers, and I'd like to understand what technologies are available for my front yard. (I would also ask for product links, but I believe those are discouraged on StackExchange sites ...) So my questions:
What moisture sensor technologies are commonly and successfully applied by consumers?
Investigating one such product, I came across the following gem explaining their technology:
Baseline Soil Moisture Sensors work by sending a high frequency pulse of electricity down an embedded wire path. The high frequency of the pulse causes the sphere of influence to move outside the sensor blade and into the soil around it. When the pulse travels through moisture, it slows down. The sensor measures the speed, and then converts this measurment to a moisture content reading.
Assuming they don't mean "the sphere of influence is moved by advanced magic muggles can't possibly comprehend", what technology might they refer to and how does that work?