Hi,
I read your project requirements. You need a system which can get soil moisture (and air quality) as inputs from the sensors and operate a fan according to those inputs.
I have done several electronic projects in the past. I have used several micro-controllers, sensors, actuators and user interfacing modules for those projects (You can see my profile and portfolio).
I am planning to do this project using Arduino platform so you can buy ready-made circuit boards and connect sensors and the fan easily.
I will provide you,
1. List of required components
2. Instructions to set up the hardware
3. The software
4. Instructions for uploading the code
5. Instructions for testing and troubleshooting
6. Any additional information regarding the system
I can assure you I will complete this project successfully before deadline.
You can contact me for any clarification.
Kind regards,
-Akilan