Confined animal production systems produce large amounts of manure tha
t are usually disposed on limited land areas in proximity to the sourc
e. There is concern that continuous heavy manuring may saturate the so
il's capacity to retain manure-P and result in groundwater contaminati
on with excessive P. The objectives of this research were to determine
the fate of waste-P in heavily manured soils and assess the risk of s
oil and water quality degradation in turkey (Meleagris gallopavo) and
beef (Bos taurus) feed lot production areas. All soils were calcareous
throughout the profile. Samples were collected by 30-cm depth increme
nts to a depth of 210 cm or a limiting layer and were analyzed for NaH
CO3-extractable P (including inorganic and organic), and total soil P.
Large amounts of extractable organic P in the surface soil layers dec
reased to background levels within 2 to 3 yr after manuring ceased. In
heavily manured fields extractable inorganic P was well above backgro
und concentrations to as deep as 210 cml apparently because of mo-ceme
nt and subsequent mineralization of organic P, Organic matter in these
soils was about twofold higher than background levels. There appeared
to be no practical limit to the P-retention ability of these calcareo
us soils. Under these conditions the risk of groundwater contamination
bg organic or inorganic P from waste P disposal to land is negligible
.