Irrigation enhances the growth of widely-spaced shade tree liners and other material planted in the field. Watering by overhead sprinkler is prohibitive because of the volumes of water required. Trickle irrigation offers an alternative.
Depending on plant spacing, thick-walled rowcrop tubing or a pipe with individual emitters is placed down each row. Ideally, one emitter should be placed at the base of each plant to wet only its root zone, but rowcrop tubing can be used to wet a continuous strip down the row (see Wetting Patterns diagram).
Tubing with built-in emitters is easier to use than installing the necessary number of emitters at the correct spacing into ½-in. or ¾ in. polyethylene pipe. Built-in emitters may cost a little more, in some cases, but they are better protected when attached inside the pipe.
Rowcrop tubing has an "allowed length of run" to ensure a certain uniformity of discharge. If a longer run is needed the tubing can be run toward both ends of the field from a submain laid across the middle.
Elevation changes will affect the uniformity of discharge. Products with "pressure-compensating" emitters are available for slopes and rolling terrain.