Row crops

Flushing

Manifold flush valves for a row crop subsurface drip system Photo: L. Schwankl

The first steps in flushing a row crop microirrigation system are to flush the mainlines and then the submains using flush valves, which should have been installed in the system and sized to allow sufficient pipeline flow velocity to wash away contaminants. All filters on the system should also be examined to ensure that they are clean and operating properly.

Flushing manifolds, especially in row-crop drip tape systems, are used at the ends of laterals to reduce the labor needed for flushing. These manifolds must be properly designed to ensure that the deposited material is removed from the system; it should have a flushing water velocity of 1 foot per second.

Flushing should continue until clean water flows out of the end of the lateral or manifold flush valve. It may be advantageous to allow the clean water to flow for an additional few minutes to allow additional surges of silt-laden water to be flushed from the system. Collecting samples of the flushed material to determine its composition is recommended.