Animal inventories on one date of the year are representative of inventories throughout the year.
If inventory data are not available, the number of animals sold
can be substituted if an appropriate
production period is used.
(We used the number of animals sold for broiler chickens and slaughter turkeys.)
Heifers (that have not calved), steers, bulls and calves can be
grouped into the category of other cattle and calves in order
to maintain consistency in cattle and calf groups over the period
of analysis. The average weights and amounts of phosphorus excreted of "other
cattle and calves" are those of steers and bulls and their recoverable
manure phosphorus fraction is that of feeder cattle.
Table of manure production factors
The tons of nitrogen and phosphate
fertilizer appplied in a county can be estimated according to
its percentage of the tons of fertilizer sold in the state.