@Jammit, which sensor are you interested in installing?
In theory, yes -- however there are few soil moisture sensors on the market that are affordable and send actual soil moisture data back to the controller. Most work similar to a rain sensor and simply interrupt the common wire, which disables the controller. For more information, please refer to this support article.
There are a few other controller's available in the US market that have proprietary soil sensors available. I do not know the cost off hand, but I believe the sensor itself is more than our controller. Let me know if you'd like more information on these systems.