PUBLICATION 442-757 Filtration, Treatment, and Maintenance Considerations for Micro- Systems Julie Shortridge, Assistant Professor and Extension Specialist, Biological Systems Engineering, Virginia Tech Brian Benham, Professor and Extension Specialist, Biological Systems Engineering, Virginia Tech Micro-irrigation systems can deliver water and nutri- Identification and Diagnosis of ents in precise amounts and at controlled frequencies directly to the plant’s root zone. With micro-irrigation Emitter Clogging systems, an extensive network of pipe is used to distrib- Clogging in micro-irrigation is often only identified ute water to emitters that discharge it in droplets, small after it becomes a problem – for instance, by noticing , or through mini-sprayers. The major cause of that some plants are not receiving enough water. How- failure in micro-irrigation systems is emitter plugging. ever, there are a number of actions that you can take Emitter plugging can severely degrade irrigation system to avoid clogging problems before they occur. Plug- performance and application uniformity. Because the ging hazards for micro-irrigation systems fall into three emitters are small and can easily plug, it is important to general categories: physical (sediment), biological or understand the filtration and maintenance requirements organic (bacteria and algae), and chemical (scale). Fre- of these systems and be proactive to prevent plugging. quently, plugging is caused by a combination of these The basic components of a typical micro-irrigation sys- factors. The type of emitter plugging problems will vary tem are shown in Figure 1. with the source of the irrigation water. Water sources can be grouped into two categories: surface and ground The goal of this document is to provide information on water. Each of these water sources is likely to present common problems that can lead to emit- specific plugging hazards. ter clogging, and how these problems can be addressed through water treatment and system maintenance. This should help producers identify, prevent, diagnose, and address clogging problems in their micro-irrigation systems.

Figure 1: Schematic of mi- croirrigation system (courtesy of Kansas State University)

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VT/0218/442-757 (BSE-222P) Water Quality Analysis a water sample can be measured by how the sample The quality of the irrigation water will determine, in conducts electricity. A water quality analysis will part, the filtration, maintenance, and water treatment sometimes report electrical conductivity (EC), usually measures that are required to prevent emitter plugging in units of micromhos per centimeter (µmho/cm). To and maintain good system performance. The emit- estimate parts per million (ppm) of dissolved solids as ter characteristics, in particular the size of the emitter shown in Table 1, multiply the EC reading in µmho/cm opening, also play a part. by 0.64. For example, if the report indicates an EC of 1000 µmho/cm, then the dissolved solids concentration When analyzing water for potential use in a micro- is approximately 640 ppm. Instead of p