Test PB Collection: FTE

Surface drip tape systems have the drip tape on the soil surface or with just enough of a soil cover over the tape to protect it from the wind and sun. You generally have good access to the exposed drip tape laterals, so pressure and discharge measurements are relatively easy to take.

Single-line drip system used in a young orchard. Photo: L. Schwankl.In a perfect microirrigation system, every emission device (drip emitter or microsprinkler) would be discharging water at exactly the same rate.

A flow meter installed at the head of a microirrigation system or small flow meters placed at the head of selected lateral lines can help you detect clogging. Saddle-mount propeller meter installed at the head of a drip system. Note the instantaneous (gpm) and totalizing (gal) registers. Photo: L.

Drip emitters were sampled in a vineyard system designed with two 0.5 gph drip emitters per vine and the vines planted on a 7 foot x 11 foot spacing. Thirty-six drip emitters were sampled by measuring the water discharged from each emitter for a 30-second period.

Application uniformity of microirrigation systems is usually measured using distribution uniformity (DU) or emission uniformity (EU).

Microsprinkler with missing head Photo: L. Schwankl.Leaks in above ground microirrigation systems are easy to detect, but to do so you really have to inspect the system.

Citrus orchard snail blocking the distribution pattern from a microsprinkler Photo: L. Schwankl.Partial clogging of emission devices, especially drip emitters and drip tape, is often difficult to detect.

Filter station with both sand media filters and screen filters Photo: L. Schwankl.Filters are most frequently located at the head of the microirrigation system, but they may also be located in the field (secondary filters, often screen filters).

Flushing of drip tape lateral ends Photo: L SchwanklA 200-mesh filter will not remove particles of fine sand, silt, and clay or fine particles of algae. They will pass through the filter and be deposited in the drip lines.

Pre-set pressure-regulating valve at the head of a drip tape lateral line. Photo: L. Schwankl.Pressure-regulating valves are used in a microirrigation system to maintain a desired, constant pressure downstream of the regulating valve even if the pressure upstream of the valve fluctuates.