Sumner (1990) compared the effects of surface
application of phosphogypsum vs. mechanical mixing
of the soil or mechanically mixing lime into a coarse
sandy loam soil with an argillic horizon in the subsoil.
Peaches exhibited only a slight response to surface
phosphogypsum application but responded significantly
to both mechanical treatments. The lack of
response to gypsum was credited to the greater sensitivity
of peach roots to physical rather than chemical
barriers in the subsoil.