The fate of radium-226 in Florida phosphogypsum was
investigated by Mays and Mortvedt (1986). They
applied phosphogypsum containing 25 pCi g-1 226Ra at
rates up to 112 Mg ha-1 to the surface of a silt loam soil
and grew successive crops of corn (Zea mays L.),
wheat (Triticum aestivum L.), and soybean (Glycine
max L.). Application of phosphogypsum even at the
112 Mg ha-1 rate had no effect on the radioactivity
levels in grain of corn, wheat, or soybeans. The 112
Mg ha-1 rate was more than 200 times the normal rate
of gypsum used for peanut fertilization. Additionally,
they noted no increases in grain Cd levels, but at the
highest rate they found that corn growth slowed. They
speculated that the slower growth was due to an
imbalance of Ca and Mg.