I am searching for a sensor capable of sensing moisture in soil. I am looking for information and I think the best way to do it is using a capacitive sensor. But nevertheless, in my application, the sensor is attached in a farm tractor, that means, the sensor is moving with the farm tractor at 2-4m/s. Also, I need to measure the humidity in depth ground, then, the sensor needs to support mechanical stress, The tractor is going to soft the ground to prevent the sensor from being damaged by the hardness.
Maybe the sensor can be readed using the capacitance to digital converter refered here soil moisture sensor design.
Another options is to build the sensor using a galvanic cell as described in 3 using a zinc and copper stakes. The voltage produced can be used as measurement of the water in soil.
The questions is, what type of soil moisture sensor is suitable for my needs? taking into aocunt that the measurements must be fast and the sensor must be able tosupport mechanical stress.
I am sure that anyone can helpme to solve the problem. Thank you for your help have a nice day :).