Based on current research results from Iowa and neighboring states, the Using
Manure Nutrients for Crop Production publication (PMR 1003) was recently
updated to reflect new manure nutrient availability ranges for crop production.
Beef cattle and dairy nitrogen availability ranges are now 30-50 percent of the
total nutrients applied, and phosphorus ranges are 80-100 percent of total
nutrients applied. These ranges increased slightly from 40 percent to 50 percent
for the upper end of the nitrogen range and 60 percent to 80 percent for the
low end of the phosphorus range.
Manure nutrient availability values are important when it comes to manure
application, since the manure rate to supply crop available nutrients is
calculated based on the specific manure source being used.
"For manure nitrogen and phosphorus, there is usually a mix of organic and
inorganic materials that varies among manure sources, production systems,
bedding, storage systems and handling," said John Sawyer, professor and
extension soil fertility and nutrient management specialist at Iowa State
University. "These ranges account for the variety of factors that can
affect nitrogen and phosphorus availability to crops."
Additional text describing the table of manure nutrient availability values was
added, along with the new URL for the revised Corn Nitrogen Rate Calculator
website (cnrc.agron.iastate.edu).
The Using Manure Nutrients for Crop Production publication includes information
about manure nutrient availability for crops, manure nutrient supply, manure
nutrient application recommendations, adjusting for manure nitrogen
volatilization, and more. You can download the revised document online for free
at the Extension Store.