I'm having issues with salinity of my soil. Even with amendments, the soil appears to be doing harm to my photinia bushes. Interestingly, I have 6 bushes in my yard, the ones that never receive look final (south side of yard), but the ones on the north side (lots of light) appear to have either salinity issues or iron deficiencies. See the photo.

My garden hose is used to water all six plants, so I'm not sure whether water quality is contributing to the issue. Someone told me Epsom salt helps reduce soil salinity. I'm not sure if this is true.

How do you reduce the salinity of soil? Is there any amendments that I can use to reduce it? Gypsum? Any help is appreciated.