Survey

Appendix 1

Table A-1-1. General summary of micro-irrigation problems and possible solutions (Burt et al., 1998).
Problem Possible solution
Small slimy bacteria
  1. Continuously apply chlorine at low dosage. Free chlorine at the far end of the system should measure 1 ppm.
  2. Superchlorinate to 200-500 ppm free chlorine at the far end of the system: Thoroughly flush system, inject chlorine, allow to sit overnight, flush system the next day.
Iron and manganese bacteria
  1. If the bacteria inhabit the well, injecting acid or chorine directly into it may minimize the problem. Check for legality of this procedure in the local area.
  2. Pump well water into a reservoir and aerate it before pumping it to the irrigation system. The oxidation will cause precipitation of iron and manganese.
  3. Inject a long chain linear polyphosphate or polymaleic acid into the irrigation water to sequester iron and manganese, keeping them suspended while they move through the irrigation system.
  4. Inject chlorine gas (1.4 parts chlorine for each 1.0 part iron in the water) prior to a fine media or disc filter to precipitate the iron from the water and trap it in the filter. This technique will not work for manganese.
Calcium and magnesium carbonate precipitation
  1. Neutralize the carbonates by injecting phosphoric or sulfuric acid into the irrigation water such that the pH decreases below 6.5.
  2. Inject a very long chain linear polyphosphate into the irrigation water at a rate of 1 to 2 ppm to sequester calcium and magnesium, keeping them suspended while they move through the irrigation system.