Microirrigation Systems for Vineyards
Chemical Treatment - Acidification
Mineral precipitates can form deposits (scale) that clog emitters. The most common deposits are calcium or magnesium carbonates and iron oxides. Since precipitation occurs more readily in water with a high pH (above 7.0), precipitation of these compounds can be prevented by continuous injection (whenever the system is operating) of a small amount of acid to maintain water pH just below 7.0.
Types of Acids
Acids that can be added to the irrigation water include sulfuric acid, hydrochloric, muriatic acid, and phosphoric acid. Urea sulfuric acid, an acid with nitrogen fertilizer value, can also be used. This product is safer to use and is marketed as N-pHURIC®.
Injection Rate
The amount of acid required to treat a system depends on: (1) the strength of the acid being used; (2) the buffering capacity of the irrigation water; and (3) the pH (of the irrigation water) needed to dissolve mineral precipitates in the lines and emitters. The required pH of the irrigation water (target pH) depends on the severity of mineral deposits.
Application
After the desired amount of acid has been injected and distributed throughout the drip irrigation system, turn the system off and let the low pH water remain in the lines for several hours, preferably overnight. This allows sufficient reaction time for the acidified water to dissolve mineral precipitates.
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