We used home-made pvc tubes with lots of holes drilled around them when we planted the mesquite tree to get the roots to seek water at a deeper level. I use a filter on the hose bib that controls the salt. Look for the filter in the misting section of HD or at any good sprinkler supplier, like Ewing or Sprinkler World. HTH.

No matter which type of watering system you use salts (calcium, sodium, magnesium, etc.,) will be carried with the water and deposited where the water stops. In our clay soils water easily moves horizontally in the soil as well as vertically. Salts could accumulate below the root zone or beside the root zone. In addition, as moisture evaporates from the soil it can draw salts along with it leaving them at the surface of the soil.

This is why using long irrigation cycles are better for plants than short frequent ones.

To manage salts, water for an extra long time to 'push' the salts away from the root zone (leaching) once or twice a year.

Here is a link that might be useful: Landscape Watering by the Numbers

@aztreelvr: Good one. I'm going to start doing that.

I agree w/ treelvr,

A common water filter won't remove salts. You'd need to use a reverse osmosis machine for that.... That wouldn't make sense...

Periodic, deep drenching watering is the best strategy (just don't look at your water bill...)

The A2wh "grow dryland" product can supply water to start mesquite trees. It extracts the water from air so no salt is added to the soil. The full plan also includes micro capture which harvests rain fall and can help flush salt out of the root zone.