This instructable is a guide for setting up an automated gardening system using an arduino and other cheap electronic parts. It allows sustainable gardening by using sensors to determine soil moisture, as well as a webscraper to determine future weather. It uses this information to save water by only using the requisite amount. Requirements for this project include experience soldering, some basic programming experience, and much patience for debugging.
See video for example of why we need this.
Step 1: Build-Moisture Sensors
The moisture sensors rely on the resistivity of water to determine the moisture level of the soil. The sensors measure the resistance between two separate nails by sending a current through one of them and reading a corresponding voltage drop due to a known resistor value. The more water the lower the resistance, and using this we can determine threshold values for moisture content.
We will use three such sensors and use a multiplexor to alternate reading between them without using more than one arduino analog port.
While we will include a circuit board diagram, we recommend building the circuits on a breadboard first which will allow for both understanding and debugging.
Each sensor uses two nails, a 100 ohm resistor, and a 100 K-ohm resistor. We built a casing for each sensor with acrylic tubes, however this is not necessary.