I have setup an Arduino Uno connected to both moisture sensors. The objective of this test is to determine how well each unit functions in it's intended environment.

As you can tell from the above image, I've taken a couple of lettuce seedlings and placed them into a pair of tin cans. I've aerated the bottom of the can by drilling small holes and adding a 3d printed spacer.

The two sensors that I have chosen for testing are the DFRobot Capacitive Soil Moisture Sensor, and the DFRobot Resistive Soil Moisture Sensor. Here are the links to the two product pages respectively.

https://www.dfrobot.com/product-1385.html

https://www.dfrobot.com/product-599.html