In the June 2012 issue of Nuts & Volts, they did a spread about making a soil moisture sensor with an iPhone interface:
And when I heard my girlfriend say that she has trouble remembering to water her plants, I put two and two together.
Most of the N&V article discussed the code required to interface with the iPhone, but the important part for me was that their soil moisture sensor was nothing more than a simple conductivity sensor. The more water in the soil, the lower its resistance.
Such a sensor doesn’t measure soil moisture in any kind of universal unit, but for a single sensor in a particular soil sample, the measured conductivity is repeatable and proportional to the moisture level. I call these conductivity units “AMU”s or “Arbitrary Moisture Units”.
Neat project and nice build!
Adafruit publishes a wide range of writing and video content, including interviews and reporting on the maker market and the wider technology world. Our standards page is intended as a guide to best practices that Adafruit uses, as well as an outline of the ethical standards Adafruit aspires to. While Adafruit is not an independent journalistic institution, Adafruit strives to be a fair, informative, and positive voice within the community – check it out here: adafruit.com/editorialstandards
Stop breadboarding and soldering – start making immediately! Adafruit’s Circuit Playground is jam-packed with LEDs, sensors, buttons, alligator clip pads and more. Build projects with Circuit Playground in a few minutes with the drag-and-drop MakeCode programming site, learn computer science using the CS Discoveries class on code.org, jump into CircuitPython to learn Python and hardware together, TinyGO, or even use the Arduino IDE. Circuit Playground Express is the newest and best Circuit Playground board, with support for CircuitPython, MakeCode, and Arduino. It has a powerful processor, 10 NeoPixels, mini speaker, InfraRed receive and transmit, two buttons, a switch, 14 alligator clip pads, and lots of sensors: capacitive touch, IR proximity, temperature, light, motion and sound. A whole wide world of electronics and coding is waiting for you, and it fits in the palm of your hand.
Have an amazing project to share? The Electronics Show and Tell is every Wednesday at 7pm ET! To join, head over to YouTube and check out the show’s live chat – we’ll post the link there.