Are you talking about using the water from acid sulfate soils (i.e. groundwater) to irrigate, or irrigating areas that have acid sulfate soils? If the soil is potential acid, i.e. not oxidised yet, then the water might not contain high concentrations of ions, but in Australia they normally contain high iron, in India and bangladesh some contain high arsenic, and obviously it gets worse with pH decreases. You're going have to look at the state of the soil in saturatured conditions and try to work out redox states and potential reactions, although irrigating over acid soils is potentially hazardous (the water table should be high anyway). Perhaps this isn't what you're talking about. Can you give an example scenario?
thanks ...I mean I will Irrigate my soil (which it is potential )with the water in the same area that has been affected by the acidity so the quality of this water became so bad from this effect, how can I treat this water to irrigate my soil?
well you can always lower the pH of the water simply by using lime or some other pH buffer. However, I think that is the easy bit. When you extract the groundwater, you run the risk of oxidising the soil, and mobilising things like metals, which would probably end up in your water. If you have high arsenic or iron, this would be a problem for crops and consumption. If you can lower the pH of the soil (lime?) then your water should improve but it would be very hard to thoroughly treat the soil. You could also try some water treatment to get rid of any nasties like arsenic or iron. Iron should should flock out easily as pH rises, not sure about arsenic, but probably the same. Try looking at some acid mine drainage solutions, as these deal with this sort of thing all the time in a thermodynamic water treatment sense. But as time goes on your treatment systems might end up with a fair bit of waste metal, which could be hard to deal with.
Check out some of these links as ASS is a big problem in some parts of Australia, especially Queensland (although we generally dont have the arsenic issue). Some solutions could be drainage to keep the soil zone away from the acid groundwater zone, but be aware that in some cases innappropriate irrigation and drainage has led to loss of irrigation/cropping lands in some areas, environmental pollution and fish kills, and saline intrusion. Good luck!
http://www.nrm.qld.gov.au/land/ass/pdfs/qass_mgt_strategy.pdf
http://www.epa.sa.gov.au/environmental_info/water_quality/acid_sulfate_soils_ass
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