Pork producers place a high value on nutrient resource application, but managing this valuable production byproduct is increasingly difficult. Dr. Scott Radcliffe, associate professor of animal sciences at Purdue University spoke at a conference recently and discussed his research.
As pork production has changed to a higher concentration of animals raised in buildings, it has become more challenging to ensure nutrients are applied correctly to surrounding cropland. Environmental concerns have led to increased regulations.
However, Radcliffe says those regulations might not be as effective as they could be. Most regulations focus on nitrogen application, but other nutrients – particularly phosphorus – can build up in the soil when looking at nitrogen alone.
Phosphorus for Plants and Pigs
Radcliffe explains that crops require phosphorus for growth. “A bushel of corn removes about 0.34 pounds of diphosphorus pentaoxide and about 0.148 pounds of elemental phosphorus. In 2010, with U.S. corn production at about 12.5 billion bushels, this equated to about 888,000 tons of phosphorus removed by corn alone,” he says.
If that’s the case, it may seem that phosphorus wouldn’t be a concern, but Radcliffe says it is still an important consideration due to land availability, application method, retention in the soil and the ratio of nutrients relative to crop needs.
Radcliffe notes that slight modifications to the nutrition program can lead to significant reductions in manure phosphorus. A market hog consuming about 707 pounds of feed in its lifetime with 0.5 percent total phosphorus content will excrete about 1.94 pounds of phosphorus. By adding phytase and reducing dietary phosphorus by 0.1 percent, the amount excreted is decreased by 30 percent.
“This results in a decrease of more than a half-pound per pig in excreted phosphorus,” says Radcliffe.