HUNTINGDON (Huntingdon
Co.) Livestock and poultry
managers should calculate nutri
ent management requirements be
fore building a new facility for ex
pansion, say two Penn State
agronomists.
“Before proposing a new facili
ty as part of a business plan, it’s
prudent to evaluate the costs and
returns of the facility under differ
ent sets of nutrient management
conditions,” said Dr. Les Lanyon,
associate professor of agronomy.
“Diffreent conditions require dif
ferent manure application prac
tices and perhaps alternative
methods of dealing with manure.”
For livestock and poultry man
agers who wish to make their own
Thinking About Building
calculations, the local Penn State
Cooperative Extension office or
conservation district office can as
sist. Private consultants and com
panies also can handle these cal
culations.
Livestock and poultry man
agers should first estimate the
available nutrients in the manure
and compare that to the require
ments of their crops. Since the
availability of nitrogen in manure
varies with how it is handled and
applied, calculations for different
periods before incorporation will
result in different acreages requir
ed to balance the supply with the
crop needs. “For example, there is
less than half as much available N
in unincorporated manure than in
manure that is incorporated im
mediately,” said Lanyon.
A nutrient management plan
based on nitrogen will require
more than twice as many acres
when manure is incorporated im
mediately than when manure is
unincorporated.
“Even though a nutrient man
agement plan may call for apply
ing manure but not plowing it un
der, nutrients might still be incor
porated into the soil by rainfall,”
said Dr. Douglas Beegle, associate
professor of agronomy.
Incorporation of manure and in
creased availability of the nitrogen
will occur with one-half inch of
rain within 3 to 4 days of manure
application. This amount of rain is
New Facility?
very likely in the early spring
when manure is being spread.
Calculating the available nitro
gen with no incorporation follow
ed by another estimate of the ni
trogen with incorporation after
three days can illustrate the range
in nitrogen that likely will be
available to crops under different
conditions. This figure can help in
deciding how many acres will be
routinely required to manage nu
trients for crop production and en
vironmental protection.
Another preliminary calcula
tion would be to estimate the bal
ance between the phosphorus in
the manure and the phosphorus re
quirements of the crops to be
grown. “Losses of phosphorus
Uncaster Farming, Saturday, April 24,1993-Dl3
during manure handling and
spreading are generally much less
than for nitrogen,” said Lanyon.
“The area required for phosphorus
application can be several times
greater than the area required to
supply the nitrogen needed by
crops.”
there’s also a possibility of un
expected costs, the requirements
for nitrogen and phosphorus man
agement may change during the
life of the mortgage or loan on a
new facility. Additional acres may
be required for manure application
at additional cost, or alternatives
to land application at the site of
the new facility may need to be
developed.
ll’s also important to get an accurate estimate
of nutrients in a planned manure storage. Esti
mating the actual nutrients to be excreted by the
animals is a good starting point to evaluate a pro
posal fora new livestock or poultry facility. This
calculation will indicate the maximum amount of
nutrients that will have to be managed.
Manure samples Irom comparable manure
storages can be used to estimate the nutrients that
will be available to be applied to crops. But il the
samples arc unrepresentative ol the manure ac
tually in the storage, then estimates of the area re
quired for manure application may be mislead
ing. “Truly representative samples arc difficult
to collect from some types of manure storage
structures,” said Lanvon.
If there is a large dillcrcntc between the esti
mate of nutrients produced and the estimate of
nutrients coming out ol a proposed storage, the
proposed storage and handling system should be
evaluated in more dcuul The source of the differ
ence between the nutrients produced and the esti
mated removal from a storage may be in the esti
mates of manure production, losses unaccounted
during handling, or in the difficulty in sampling
comparable storages
If the problem is in sampling, that may signal
potential management problems. There may ac
tually be more manure nutrients to manage than
are estimated by the samples. Manure solids that
are difficult to agitate ean accumulate in some
storages. The nutrients in these solids will need
to be handled in a sale way as will the rest of the
nutrients. Problems in sampling also can mean
that the nutrient content of the manure removed
from the storage varies widely.
Delivering a dependable amount of nutrients
to the crop fields, even when the necessary num
ber of acres is available, will be difficult when
this happens. In either case, more effort will be
required to mange nutrients for crop production
and environmental protection. These manage
ment demands should be considered before the
project is begun.
Finally, different projected crop yields can be
used in the calculations. “Projected yields should
rarely exceed by more than 20 to 25 percent the
average yields for the last five years,” said Bec
gle. It’s also important to do additional calcula
tions to estimate the different acreages required
at average and below average crop yields.
The final projected crop area for manure appli
cation probably will be a compromise between
all the different calculations. After making these
calculations, it may be necessary to modify the
business plan for the proposed livestock or poul
try facility to cover costs of manure applicauon
on a larger number of acres, to develop a man
agement strategy to enhance potential crop
yields, or to find an alternative way to deal with
the manure produced.
If these calculations are done before building
the facility, the livestock or poultry manager will
know the most demanding case from the outset.
A contingency plan then can be made in case of
changing on-farm decisions or new government
al policies.
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