I recently had our garden soil tested by and discovered that it is very high in salt at 162 and 340 parts per million for two samples where the desired level is less than 35. This has become a common problem in California because of the drought. The salt levels in municipal water supplies are very high because there is less mountain water, which is very low in salt, and so water districts need to use more well water, which tends to be high in salt.
High salt levels inhibit germination and plant growth, especially seedling growth.
Salt Toxicity in Lemons. Source: www.dpi.nsw.gov.au
Keep soil moist by watering adequately and by mulching to reduce evaporation. As water evaporates, the salt content is concentrated.
Different varieties of plants have different tolerances to salinity. The publication below "Irrigation Water Salinity and Crop Production" rates varieties by sensitivity - sensitive (S), moderately sensitive (MS), moderately tolerant (MT), and tolerant (T).
Leaching Salt From Soil
Salt can be leached out of the soil by heavy watering, ideally with rain water, since it is very low in salt, but well or municipal water can be helpful if rainwater is impractical. About 12 inches of water are needed to leach salt from soil.
During a storm this Spring, we put new garbage cans under 3 roof drains. We connected a couple of hoses together, put one end in a garbage can and the other end in the garden with a sprinkler attached. Our lot slopes down to the garden and fruit tree area, so the sprinklers were able to run from gravity pressure. The process was a bit tricky because the hose needed to be primed to start the water flowing, but it was an interesting experiment and we were able to put about 12 inches of water on four citrus trees and one garden bed.
We've now purchased better rain barrels with spigots that will eliminate the need to prime the hose and we're ready for next rainy season. We also have an electric water pump from Home Depot that we'll use to pump water to a garden in back at the same level as the house.
Irrigation Water Salinity and Crop Production (UC California Extension)