03 Dec 2007,Billy in
.
au:


Will you please support your assertion.


sand and clay = adobe.

but enough of an intermediate particle size should prevent that.

besides all this, some plants prefer sand, some prefer clay, etc.

Clay holds water and nutrients and binds the soil. Good soil will
encourage bacteria which will exude mucopolysaccharides and
further bind the soil together.

Sand silt clay and you want them in the quantities indicated
above.

practically speaking, existing grades will be destroyed if you haul in huge amounts of
soils (to meet those percentages). you could haul out similar volume of existing soil,
but all that hauling gets expen$ive. older houses sometimes have areas with an extra
inch+ of soil because someone(s) hauled in some "planting mix" This topping can be
successful for a while if the "planting mix" was brought in for shallow planting (usually
a sod install).

a similar "technique" that succeeds with some plants is adding a thin layer of gravel
at the crown.