Drip irrigation has long been used in the outdoor landscape, due to its highly effective but water conserving means of keeping even moisture around the plant roots. 

 

Top drip hydroponics systems realize high production of crops for the same reason. Nutrients trickled over the surface of the media right at the root zone bathe those roots continually in "grow juice". 

 

The result? Amazingly rapid growth with high flowering/fruit production. Due to the recycling and reuse of the nutrients via a drain and reservoir set up, there is virtually no waste of water and nutrients.