The correct answer is water and nutrients..
Ground sensors, but are actually soil moisture sensors. These are widely used to perform automatic readings often connected to the internet. With easy access to moisture information, as well as constant collection, the security of this information is much greater.
Therefore, to know soil moisture quickly, using soil sensors is a relatively inexpensive way to obtain this information. Although not as common as they could be, ground sensors have already been employed in the field by farmers who are concerned about producing with much more control.