Manipulation of animal diets can
reduce manure phosphorus (P) in areas where animal production is intensified.
Solubility of swine manure P in soils amended with phytase will provide
information on what changes occur in manure P with time. Manure samples were
collected from 28 growing pigs fed randomly with seven dietary treatments at
different levels of phytase. The seven treatments were: A positive
control (NRC) that contains P at NRC (1998) recommendations, a negative control
(RED) containing 0.1 percentage units
reduction (about 33%) in available P from 1998 NRC recommendations, RED + PHY1
(RED plus 500U of phytase / kg of diet), RED + PHY2 (RED plus 1000U of phytase
/ kg of diet), a double negative control with no added inorganic P (DNC), DNC +
PHY3 (with 2000U of phytase / kg of diet), and DNC + 4000U of phytase / kg of
diet). Manure (feces+urine) from 4
replicates of each treatment were mixed to form a composite and the total P
determined. This manure was added to four