Una wrote:
In places with high salt content in the soil already, soil amendments
that are high in salts can be bad news.

Doug Freyburger wrote:
I take it salt in soil is a sign of poor drainage and/or insufficient
rainfall.

In some places the salt is of geological origin: former seabeds. The
groundwater in some parts of the world is so heavily laden with salts
*from within the ground* that it is not drinkable and very few species
of plants can survive either. It takes a *lot* of rainfall to remove
so much salt.

One cause of desertification is centuries of extraction of organic
matter, and soil nitrogen, by humans. Intense agriculture does that,
where biomass is produced in one place and consumed somewhere else.

Una