2.2 Micro- or Trickle Irrigation Systems

The terms microirrigation and trickle irrigation can be used interchangeably. Trickle or drip irrigation were terms used to describe individual emitters or rowcrop emitters. Microirrigation is a broader term that is used to cover all forms of small emission devices including individual emitters, rowcrop tubing, spray strakes, and micro-sprinklers. All of these devices were developed for water distribution to small crop area, frequently to individual plants.

Microirrigation systems have very small openings, called emitters, that are designed to discharge the water at a known rate for the operating pressure. Different emitters have different sensitivities to pressure changes and water quality. Water filtration of 150 to 200 mesh is required to ensure good operation. Most emitters operate at pressures of 8 to 20 psi, with flow rates of 0.5 to 2.0 gallons per minute for individual emitters or 0.5 to 1.5 gallons per minute per 100 feet of length for rowcrop tubing.

Emitters are designed to be self-cleaning or to be taken apart for cleaning. Periodic chlorine injections are used to keep the system free of algae or bacterial slime. Acid injections, along with periodic system flushes, help to remove mineral buildup. Backflow prevention devices should be used to protect the water supply when chemical are injected.

Microirrigation irrigation systems require more planning than overhead sprinkler systems because the emitter systems deliver water directly to the plant root system. The crop influences the selection of the emitter system. There are many types of emitters to meet specific needs.

Water conservation, energy conservation, and automation are accomplished by microirrigation. Both water and nutrients can be delivered efficiently. Applications of the system can be found in all kinds of nursery/greenhouse production systems.

Liners can be watered using trickle rowcrop tubing or individual trickle emitters inserted in polyethylene pipe. Container-grown crops use rowcrop tubing, individual emitters in pipe, spaghetti tube systems, or spray stakes to lessen water requirements and achieve adequate coverage. On inground or raised bed plantings, trickle rowcrop tubing can adequately wet the soil. We will now examine each each system in detail in the following three subtopics:

a. Field production

b. Aboveground container and/or Pot-in-pot production

c. Raised Bed production