Net irrigation Depth of water, exclusive of effective precipitation, stored soil moisture, or ground water, that is required for meeting crop evapotranspiration for crop production and other related uses.  Such uses may include water required for leaching, frost protection, cooling and chemigation.

Net positive suction head Head that causes liquid to flow through the suction piping and enter the eye of the pump impeller.

Nipple A 12-inch or shorter pipe that has threads on both ends used to join fittings. A close nipple has threads that run from both ends to the center.

Nominal Size Named size which  is usually not the actual dimensions of the product.  i.e. a half inch schedule 40 pipe is not  1/2 inch ID or OD.

Nonbeneficial use  Water utilized in plant growth which can not be attributed as beneficial.

Nonconsumptive use Water that leaves the selected region and not considered consumptive. Examples are runoff, deep percolation, and canal spills.

Nonpoint source pollution Pollution originating from diffuse areas (land surface or atmosphere) having no well-defined source.

Non-saline sodic soil Soil containing soluble salts that provide an electrical conductivity of saturation extract (ECe) less than 4.0 mmhos/cm and an exchangeable sodium percentage (ESP) greater than 15.  Commonly called black alkali or slick spots.

Nozzle Final orifice through which water passes from the sprinkler or emitter to the atmosphere.

Number of outlets Term used to describe the number of outlets in a lateral.