BonTmToßici
Understanding Grain Shrink
J. Allan Shoener
Schuylkill County
Extension Agent
The selling of grains requires
several considerations, and one
of the least understood seems to
be the elusive and mysterious
loss of weight as adjustments
are made from harvest to mark
et moisture levels.
If grain is dried using heated
air, the cloud of steam rising
can be seen, and it is easy to rec
ognized that this is moisture or
water being removed from the
grain. There is also a visible set
tling or reduction of volume of
the grain as a result of the mois
ture removal.
This reduction of volume
also occurs and is noticeable
when grain is dried by ambient
air. A good example is the set
tling that takes place in a crib of
ear com over a period of time.
The weight lost during drying is
shrink and is expressed as a per
centage of the original quantity
before drying.
The loss of moisture can be
seen and recognized that it does
occur. So where does the confu
sion and misunderstanding
occur? Probably in the some
what complicated mathemati
cal calculations that are used to
determine the amount of shrink
and maybe in the way these cal
culations arc applied.
Often these calculations are
referred to as pencil shrink a
procedure used by grain buyers
to calculate how much grain
they will actually have after the
grain they buy is dried.
There is no standard method
of pencil shrink. That is to say
that not all grain dealers use the
same system for calculating
grain shrink. In fact, several
valid methods are in popular
use. This makes it important to
compare the potential net return
of the sale of a quantity of grain
and not just the price per bushel
offered. Grain growers can
maximize the net sale of their
products by understanding pen
cil shrink and evaluating sale
alternatives.
There are two components to
consider when calculating
shrink. The first is water shrink,
which is the weight of the water
removed in drying. Total water
shrink is equal to the pounds of
water removed during drying,
divided by the original weight.
This number is then multiplied
by 100 to express the shrink
factor as a percentage.
The calculation would be
easy to do if the wet grain deliv
ered to the dealer was weighed,
dried as a batch by itself, and
then weighed again when dry.
But then the percent shrink
would not need to be known
because the dry grain weigh!
would already be known. The
problem is that grain is not
handled by the delivered load
or batch but is mixed with othei
deliveries and generally dried
on a continuous basis. There
fore, it is necessary to have r
method to calculate the watei
shrink when the wet grain if
delivered.
A series of mathematical cal
culations can be used to accu
rately determine the water
shrink for each load of grain.
Another system often employ
ed is to use water shrink factors
which are calculated values
representing the percent shrink
for each point of moisture
removal to a given dry grain
level.
Using shrink factors gives
accurate results by relying on
predetermined values while eli
minating the need for more
complex calculations. Using
this method, the total water
shrink is equal to the number of
percentage points of moisture
removed multiplied by the
water shrink factor.
The second component ol
shrink is handling loss. In addi
tion to the water weight lost
from drying, a small amount ol
dry matter is also lost. This is
called “invisible shrink” oi
PgiliF Mill
Your Complete Headquarters For
Sprayers And Parts
Self Priming Pacer Pumps
Raven Tough Polyethylene Tanks
~ ' F PI N AY or R R T f NKS ' ALL SIZES
K# STATIONARY FROM
We Also Stock A Complete Line Of:
fMISk Hypro x DAppp • Sprayer Hose
■HUH rm/UiR • Ball Valves
Sprayer Nozzles And PUMPS • Nylon Fittings I
Accessories Accessories , poly Tanks
PAUL B. ZIMMERMAN, INC.
I ejp "i 50 Wood comer Rd., Lilitz, PA 17543 hours:^^ -^^
j 1 Mile West of Ephrata iMon., Thur* 4 Pn 74 30 I
lUDSI (717) 738-7350 1 Tu ‘V.*£» M I
W . HARDWARE • FARM SUPPLIES • 1 *
fy, WWR'j|'’i , vj' , VWn
handling loss and consists ol
loss of volatile compounds,
mechanical loss of broken ker
nels and foreign materials and.
seed respiration. The amount oi
handling loss is determined by
initial physical quality of com.
method of drying, and the hand
ling process during drying. The
higher the initial quality of the
grain, the lower the loss.
High heat drying will gener
ally result in higher losses. And
gentler and lesser amounts ol
handling will result in lowei
losses. According to a Midwest
study, on-farm handling losses
ranged from 0.22 percent tc
1.71 percent with a three-yeai
average of 0.82 percent, while
handling losses of commercial
systems ranged from 0.64 per
cent to 1.33 percent with a
three-year average of 0.88
percent.
In addition to recognizing
the two components of grain
shrink, it is also important to
understand that there are diffe
rent methods of calculating tot
al shrink. The first is the use of
drying tables where total shrink
is equal to the water shrink plus
the handling loss. The second is
the constant shrink factor
method where total shrink is
equal to a constant shrink factor
multiplied by the number of
points of moisture removed
from the grain.
The Penn State Agronomy
Guide contains two tables that
are useful in estimating shrink.
The first can be used to deter
mine the equivalent bushel
weight for either ear or shelled
com at moisture levels from
11.0 percent to 33.0 percent.
The second chart contains
shrink factors for grains rang
ing in moisture from 13.0 per
cent to 30.5 percent and dried to
six levels ranging from 13.0
percent to 15.5 percent by .5
percent increments. These
shrink factors include a .5 per
cent dry matter loss.
With the different methods
of calculating shrink and the
(DdDIN TMM HIWO
variables within the methods, it
becomes apparent why a price
per bushel quote alone does not
necessarily tell you where you
will receive the best price for
your grain. To further compli
cate the issue, there can be var
iations in deductions for fore
ign materials, bushel weights,
and drying charges. And
because in many cases these
charges may be lumped
together and expressed as a
single deduction percentage, it
is difficult to compare the indi
vidual charges.
Perhaps the best way of eva
luating wet grain sale alterna
tives is to compare the net price
RESEARCH
UPDATE
(Contlnuad from Pago 25)
number of broadleaf weeds
including lambsquarters, pig
weed, ragweed, and velvcllcaf.
Permit 75DG (MON 12000)
is a sister product of Battalion.
Permit is also being developed
by Monsanto for use in com,
but will be applied post
emergence. Permit is effective
on pigweed, vclvetlcaf, and
nulsedge, but tends to lose
some of it’s activity on lambs
quarters and ragweed when
applied post.
Exceed 75WG
(CGA-152005) is an experi
mental product from Ciba
LIME
• Dump Truck Loads
• Spreaders Available
92% CCE Calcium Oxide 43%
ENP 69 Magnesium Oxide 6%
55% passing 100 mesh
65% passing 60 mesh
98% passing 20 mesh
NOW ONLY 5 5 50 Per Ton (Picked Up)
Lititz, PA • (717) 626-9760
* CRUSHED STONE & READY-MIX CONCRETE *
Registered with PA Department Qf Agriculture
you will receive for a load of
grain where the net price is
equal to the price per bushel
multiplied by the number of
bushels after adjustments in
quantity and/or price have been
made. To do this, instead of
calling the grain dealer and ask
ing the price being paid for a
bushel of grain, ask what will
be paid for your load of grain
weighing a specified number of
pounds and at the wet moisture.
You may not know the exact
weight or moisture level, but by
using the same numbers with
several dealers you will be able
to more accurately compare the
prices being quoted.
being tested for its broadlcaf
activity in com. Exceed is a sul
fonylurea and will probably be
applied postcmcrgcncc because
of crop safety concerns with
soil applications. Foliar appli
cations of Exceed show good
crop safety and are effective on
a number of broadlcaf weeds
including lambsquarters, pig
weed, velvetleaf, ragweed, and
burcucumbcr.
Resource 0.86 EC
(flumiclorac-penlyl/V-23031)
is an experimental product
from Valent. Resource belongs
to a new herbicide family and is
a cell membrane disrupter
(contact-type). Resource will
be applied poslemcrgcncc for
broadlcaf weed control in com
and soybeans. The product is
rather narrow in spectrum and
will probably be tank-mixed
with other products to broaden
the spectrum. Velvetleaf will be
a main target of Resource.
Editor’s Note: The author
and Penn State University do
not imply endorsement of any
product mentioned in this
paper.