A neighbor complained when his azaleas were adversely affected by a generous application of limestone to the lawn immediately surrounding the azaleas. To what do you ascribe this difficulty? How would...

A neighbor complained when his azaleas were adversely affected by a generous application of limestone to the lawn immediately surrounding the azaleas. To what do you ascribe this difficulty? How would you remedy it?

The ill effects of acidity in subsoils can be ameliorated by adding gypsum (CaSO₄
· 2H₂O) to the soil surface. What are the mechanisms responsible for this effect of the gypsum?