Question

what is one of the biggest problems with excessive irrigation?
plants drying out too quickly
soil salinization (increased saltiness of the soil)

Explanation:

Excessive irrigation can lead to waterlogging, and as water evaporates, salts present in the water or soil are left behind, increasing soil salt content (soil salinization). Plants drying out quickly is not a result of excessive irrigation (as excessive irrigation provides more water, not less).

Answer:

soil salinization (increased saltiness of the soil)