Over-fertilization can alters Soil Salinity and pH:
I am citing a paragraph from a website (see link below): "Excessive fertilizing can cause a build up of fertilizer salts, raising soil salinity and altering the pH of your garden. Plants in highly saline environments suffer significant root damage, which can lead to an inability to take up nutrients and water properly. Seed germination may slow or stop in the presence of excessive salt. Lower soil pH as a result of over-fertilization also makes nutrients less available, leading to a variety of nutritional deficiencies."
1. Except altering the pH, over-fertilization can also cause the accumulation of salt, and these can affect the growth of plant-beneficial bacteria in the soil.
2. In addition, high organic matter levels can cause poor drainage (see attached article, yellow highlights).
Article title: Over-Fertilization of Soils: Its Causes, Effects and Remediation