Il 2010-02-17 06:01, Desmond Armstrong ha scritto:
My garden soil in Jacksonville, OR is heavy clay that dries out and
becomes hard and water resistant during summer. Water can puddle on the
surface, but if the soil is scratched, it is bone dry a quarter of an
inch below, and plants would die of drought in spite of frequent watering.

This is the typical beauvoir of clay soils. You can improve them by
means of organic mater and/or bivalent cations like Ca++ (from lime), or
Mg2+. Cations endowed of 2 positive charges create a bridge between two
clay molecules and allow many molecules aggregate and create flakes with
spaces among clay clots. By this way air and water can move through the
clay particles to the plant roots.


I found by experiment that if ammonium sulphate is sprinkled on the clay
and watered, it gradually sinks in, and when enough is applied, the clay
becomes soft, crumbly and permeable to any desired depth.

Monovalent cations like NH4+ (ammonium), or Na+ (Sodium) can't create
any bridge-bound between clay particles, but they can only saturate the
clay's negative charges, make them precipitate in the soil solution.,
making the soli more compact.

What could have happened to your plants is that SO4- (solforic) ione
reacting with Na+ (frequently stored over the soil surface in hot
climates), has generated Na2SO4 and then water can have taken it away.

Salts when stored on the soil surface can prevent water enter the plant
roots.

In that case your problem could be a salt soil, instead of the clay
ratio. All this can explain the effect of ammonium sulphate, cause of
the sulphate, that reduce pH in alcaline soils making them more acidic.
I hope this helps,
bye