How is a moisture sensor probe able to detect the amount of water ...

[natalie2426]

How is a moisture sensor probe able to detect the amount of water present in a potting medium? Under what conditions might it give a false reading?
 
  What will be an ideal response?

Question 2

In what cases would bottom watering be preferable to top watering?
 
  What will be an ideal response?

[Loise Hard]

Answer to Question 1

An electrical water sensor measures the electrical conductivity of the soil. The more water present, the more ions will be dissolved in the soil and the greater the electrical conductivity, indicating more water. It might give a false reading if the nutrients level is extremely high because the elevated level of nutrients would indicate the presence of more water than is actually in the soil.

Answer to Question 2

When the plant is a rosette type that completely fills the top of the pot or when the plant leaves are susceptible to water spotting

[natalie2426]

TYSM

[okolip]

Excellent