Soil test P (STP) is used to determine the amount o
f phosphate (P) needed for crop production as well
as to
determine environmental risks associated with eleva
ted levels of soil P.
1
Phosphorus is an environmental
concern,
because excess P often promotes weed and algae grow
th
in bodies of fresh water. Decomposition of the wee
d and
algae material reduces dissolved oxygen levels, lea
ding to odors, fish kills, and a general degradatio
n
of the aesthetic
and recreational value of the environment.
2,3,