2.Testing the Irrigation Water Source
Before implementing routine or remedial maintenance on a micro-irrigation system, test the water source for physical, chemical, and biological properties to determine emitter plugging potential. It is important to take a representative water sample:
- If the water source is a well, collect the sample after the pump has run for about half an hour.
- If sampling surface water, collect the sample near the center of the source about 1 ft below the water surface.
- Check for water source variability by taking samples several times during the irrigation season.
- To accurately measure water pH, alkalinity, dissolved iron, and hydrogen sulfide, analyze well water with a field test kit immediately after sampling.
- Use Table 1 to estimate the plugging hazard of irrigation water based on a standard analysis.
| Factor | Plugging hazard based on concentration | ||
| Slight | Moderate | Severe | |
| pH | <7.0 | 7.0 to 7.5 | >7.5 |
| Total dissolved solids 1 | < 500 | 500 to 2000 | >100 |
| Suspended solids 1 | <50 | 50 to 100 | > 2000 |
| Iron 1 | < 0.1 | 0.1 to 1.5 | > 1.5 |
| Manganese 1 | < 0.1 | 0.1 to 1.5 | > 1.5 |
| Calcium 1 | < 40 | 40 to 80 | > 80 |
| Hardiness as CaCO31 | < 40 | 40 to 80 | > 80 |
| Hydrogen sulfide 1 | < 0.2 | 0.2 to 2.0 | > 2.0 |
| Bacteria (#/mL) | < 10,000 | 10,000 to 50,000 | > 50,000 |