Trickle irrigation: Emitter clogging and other flow problems

Abstract

Trickle irrigation experiments with Colorado River water on citrus trees in southwestern Arizona were conducted to develop water treatment methods for preventing emitter clogging and maintaining long-term operation of the system under actual field conditions. Eight trickle emitter systems in combination with six water treatments were evaluated during a comprehensive 4-year study. Emitter clogging was related to emitter design and to degree of filtration treatments of Colorado River water. If not positioned upright, emitters designed with moving parts were more susceptible to malfunctioning and clogging. Emitters with flexible membranes either failed after a few months of use with chemically conditioned water or showed serious deterioration and decomposition after 4 years. Five of the eight emitter systems required sand and screen (200 mesh) filtration plus chemically conditioned water to keep suspended materials from physically clogging the emitter. However, two emitter systems with the same design but different flow rates have continued to operate with only screen (50 mesh) filtration. For emitters unaffected by material deterioration, the water conditioned continuously with acid alone was just as effective as a combination of continuous or intermittent chlorine and acid treatments in reducing emitter clogging. The dominant causes of emitter clogging and flow reduction were physical particles; next, and minor in comparison, was the combined development of biological and chemical deposits.