Microirrigation Systems for Vineyards
Chemical Treatment - Chlorination
Water with a high organic load (algae, moss, bacterial slimes) should undergo chlorination. While a high organic load may be present in water from any source, it is most likely to be present at high levels in surface water from rivers, canals, reservoirs, and ponds. Although using good filters, such as sand media filters, can cut down on organic clogging, the best way to deal with the problem is to add a biocide to the irrigation water, such as chlorine. Adding chlorine to water produces hypochlorous acid, which then undergoes an ionization reaction producing hypochlorite.
Chlorine Concentration Schemes
When the purpose of chlorination is improving filtration performance, the injection point should be close to the filtration system to assure even-distribution throughout the filters. The following are several possible chlorine concentration schemes:
Sources of Chlorine
The most common chlorine sources are sodium hypochlorite (a liquid), calcium hypochlorite (powder or granules), and chlorine gas. Liquid sodium hypochlorite (NaClO) is the easiest form of chlorine to handle and is the type most often used for treatment of micro-irrigation systems.
Calculations
A grower wants to inject sodium hypochlorite that has a concentration of 5.25 percent. Calculate the injection rate using sodium hypochlorite with the following formula:
Chlorine Application Precautions
Chlorination for bacterial control is relatively ineffective above pH 7.5, so acid additions may be necessary to lower the pH to increase the biocidal action of chlorine for more alkaline waters.
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