A category of trickle irrigation in which water is applied to the soil surface in discrete or continuous drops, or tiny streams through emitters. The terms drip and trickle irrigation are often used interchangeably. However, the American Society of Agricultural Engineers practise ASAE EP405 makes the distinction that trickle irrigation includes systems with higher discharge rates than most drip systems. To be classified as drip irrigation, point source emitters should have discharge rates less than 3 gal/hr and line source emitters less than 1 gal/hr/ft of lateral.