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Group Title: Circular Florida Cooperative Extension Service
Title: Grain sampling
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 Material Information
Title: Grain sampling
Series Title: Circular Florida Cooperative Extension Service
Physical Description: 13 p. : ill. ; 28 cm.
Language: English
Creator: Talbot, Michael T ( Michael Thomas ), 1948-
Publisher: Florida Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida
Place of Publication: Gainesville
Publication Date: 1992
 Subjects
Subject: Grain -- Storage   ( lcsh )
Genre: government publication (state, provincial, terriorial, dependent)   ( marcgt )
non-fiction   ( marcgt )
 Notes
Statement of Responsibility: Michael Talbot.
General Note: "April 1992."
General Note: Cover title.
 Record Information
Bibliographic ID: UF00014453
Volume ID: VID00001
Source Institution: University of Florida
Holding Location: University of Florida
Rights Management: All rights reserved by the source institution and holding location.
Resource Identifier: ltqf - AAA6904
ltuf - AJE2370
oclc - 25967588
alephbibnum - 001729781

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Apri 199 Cirular104


Grain Sampling




Michael Talbot















Florida Cooperative Extension Service
Institute of Food and Agricultural Sciences
University of Florida
John T. Woeste, Dean


April 1992


Circular 1046












































































Michael T. Talbot, Associate Professor, Agricultural Engineering Department, IFAS, University of Florida, Gainesville








Introduction
Consistent and timely sampling of stored grain
along with analysis and proper interpretation of
test results can detect existing or potential prob-
lems before considerable damage has occurred.
Timely sampling can reveal increases in moisture
and temperature which are early signals of poten-
tial storage problems.

When sampling a bin, know the past history of
filling and unloading, and take the necessary safety
precautions. The sampler should be familiar with
the suffocation hazards in grain bins, particularly
those associated with bin unloading equipment and
what can happen when probing through bridged
grain. For more information on this subject, refer
to the extension publication entitled Grain Drying
and Storage on Florida Farms.

The sampling procedure may be divided into two
separate tests-the average moisture and tempera-
ture test, and the spot test. Each one is designed to
locate possible trouble areas.

Probing the grain for representative samples is
one means of determining average moisture and
temperatures. The more representative samples
that are taken, the higher the accuracy of the mea-
surement. Under some circumstances, such as
when a bin is too full, it may be impossible to ob-
tain all the data needed for a complete test.

The average temperature and moisture content
is the average of all the sample readings. However,
acceptable average conditions will not ensure safe
storage. If temperature differences within the bin
are greater than 10F, the aeration fan should prob-
ably be started.

Once the probe and fan tests have been con-
ducted, the bin should be examined for possible
trouble areas or "hot spots" indicating rapid mold
or insect development. Several random probes for
temperature and moisture should be made in the
center of the bin and near the bin walls and floors if
possible. The bin door may have an opening for a
probe so as to allow sampling near the floor. Suspi-
cious areas should be examined closely. In addition
to temperature and moisture content readings,
these areas should be checked for foreign material
and the presence of insects and aflatoxin. Shining
a black light onto a grain sample will give some in-
dication if aflatoxin is present because contami-
nated grain has a green-yellowish appearance. A


positive black light reading means that a more so-
phisticated laboratory test for aflatoxin should be
conducted.


When to sample
Close monitoring and sampling of temperature
and moisture is needed during storage at weekly or
more frequent intervals to ensure that moisture
and temperature are stabilized at acceptable levels.
Sampling intervals may be lengthened to monthly
or longer periods provided the moisture and tem-
perature values have stabilized and the environ-
ment outside the bin is relatively static. When the
outside environment changes due to seasonal
weather patterns, grain should again be sampled
on a more frequent basis, preferably weekly or
every other week.

Sampling should be initiated when obvious signs
of deterioration are apparent. Situations which in-
dicate that grain is undergoing deterioration are: 1)
musty or off odor coming from the grain mass, 2)
neither dew nor frost forming on the roof of a bin,
3) water vapor rising from the grain mass, or 4) an
increase in temperature or moisture in an area of
the grain. Samples should also be taken when ani-
mals either refuse grain or consume the grain and
exhibit performance or reproductive problems.
These samples should be analyzed for mycotoxins.
Management decisions made on the basis of the
mycotoxin analysis should be made in consultation
with a veterinarian.


Where to sample

Outside the bin
The grower or grain bin inspector should be alert
for tell-tale signs of storage problems when first
entering the vicinity of the grain bins. During
walks around the bin(s), checks should be made for
leaking grain, bulging bin walls, standing water,
rodent activity, insects, bin cracks, and weeds.

Observation of fresh grain is an indicator of recent
grain movement. Determine if the bin is empty by
pounding on the side of the bin. If empty, the
ground level bin door can be opened to inspect for
insects, rodents and loose grain.

If there is an aeration or drying system, the fan
or cover should be removed to inspect for rodent ac-
tivity, spilled grain, insects, and mold. If the fan is
running or can be turned on, the air passing








through the fan should be smelled for odors and the
temperature coming out of the fan should be mea-
sured and recorded. A musty, foul or odd odor aris-
ing from the fan area or other parts of the bin is
evidence of grain deterioration. Grain bins with
moisture leaks or no frost formation on the bin
roofs during freezing weather conditions are fur-
ther signs that the grain may be deteriorating.


Inside the bin
Upon entering the bin, the inspector should
check for such things as crusting of the upper layer
of grain, an accumulation of foreign matter, bin
leaks, evidence of cracked kernels and fines, or
other possible problem areas. Grain directly below
the discharge spout will usually contain the most
cracked kernels or foreign material and should be
sampled because these areas are likely candidates
for insect damage or mold. Again, notice should be
made of any foreign odors. If musty or sour odors
occur, these areas should be sampled and noted on
the recording form. Grain in this condition may be
at a critical stage where a day or two delay in
implementing an appropriate control procedure
may cause major grain loss.

If problem areas are noted, a form, such as the
one shown in Figure 1, should be used to record ob-
servations. In the absence of any apparent grain
storage problems, the following sampling proce-
dures should be used.


How to sample
Collecting representative grain samples is essen-
tial to obtain useful data. Consequently, specific
sampling equipment is recommended and certain
uniform sampling methods must be followed
closely. The sampling methods selected are practi-
cal in both time required and equipment needed.
However, the sampling procedure does not replace
the need for careful observation or judgment deci-
sion, since storage conditions and structures are
widely diverse.


Equipment
The standard piece of grain sampling equipment
most widely used is the partitioned grain trier (Fig-
ure 2). This trier is used to obtain samples to de-
termine both insect infestation and grain damage
and moisture. It consists of a long (about five feet)
double brass tube divided into compartments for
sampling at specific depths. The trier is filled by
inserting it full-length into the grain at a 10 angle
from vertical with the compartments closed and
facing up. The handle is then twisted to open the
compartment doors. The trier fills quickly by giv-
ing it three quick, short, up and down strokes in
the grain mass. It can then be removed after the
doors are closed. After a sample is taken, the trier
should be placed across a sample cloth or metal
trough to catch the grain as the compartment doors
are opened. The trier will be used to obtain a sur-


FAR M
GRAIN


BIN DATE
QUANTITY

OBSERVATIONS


X 1,000 bu


TEMPERATURES Diagram mold, hot spots, est. size, note
__ -2' at center insects present, treatments, etc.
MIDDLE NJ
HOT SPOT #1
HOT SPOT #2
FILL
LEVEL '
PEAKED
FUNNELED
SLANTED
OVERFILL




Figure 1. Grain bin observation recording form.













C0






J
0
U <-o









PARTITIONED
GRAIN TRIER


DEEP BIN EXTENSIONS
FIN TRIER T-HANDLE


0
0
ol
0
0
0


0
0
0

V_


-- I


Figure 2. Five-foot compartmentalized grain trier and equipment for deep grain sampling and grain temperature measurement.


face sample by pushing it horizontally about three
inches below the grain surface. Caution should be
followed when using the trier since the compart-
ment doors have very sharp cutting edges.

The deep-cup or bin probe (Figure 2) allows
samples to be taken from greater depths in the
grain mass than are possible with the grain trier.
The brass sample cup is inserted into the grain and
additional 3-foot extensions are added to reach the
desired depth. A short pull of the handle will open
the top, allowing grain to flow into the cup. If the
grain is too compact to flow freely, a sharp pull or
jerk will start the grain flow. When the deep-cup is
inserted, it is important for the sections to be prop-
erly locked to prevent their loss within the grain
mass. Twisting the handle while the probe is in-
serted in the grain may unscrew a connection re-
sulting in damage or loss of the cup. The tempera-
ture of the probe extensions should be noted as they
are removed from the grain to locate areas of heat-
ing (hot spots).

Temperature samples can be taken with a
shielded small diameter thermometer screwed onto
3-foot threaded pipe extensions (Figure 2). A
threaded T-handle facilitates insertion of the probe
through the grain mass. Extensions can be added
until the desired probing depth is reached. The ap-
paratus should be left in place for several minutes
before being removed from the grain to read the
temperature. Maximum probing depth with this
equipment is between 12 to 15 feet.


Grain sample bottles or metal cans are neces-
sary for holding grain samples. These containers
must be filled to capacity with grain or there will not
be enough to adequately determine test weight, in-
sect infestation and moisture content.

Sample cards are used to record observations,
sample sources, location of bottle samples, insects
present, temperatures, and to diagram conditions.
It is important that the card remains with the cor-
rect sample.

Sample bags hold a larger sample than the
sample containers described above and are lined
with plastic to minimize moisture changes and re-
duce insect escape. The bags must be sealed tightly
after filling.

The equipment described above can be purchased
from a number of agricultural and general supply
catalogs and can cost several hundred dollars.
When adequately maintained, the equipment has a
long serviceable life. When compared to the cost of a
lost storage bin of grain, the cost is well justified.

Other useful equipment includes vise-grip pliers,
50 feet of nylon rope, marking pens, flashlight, tape
measure and leather work gloves (see Table 1).

All samples should be evaluated as soon as pos-
sible because insect infestation or mold growth sta-
tus may change quickly in a sealed bag or container,
especially if the samples are not kept cool.


TORPEDO
& DEEP BIN CUP
PROBE


THERMO SAMPLER S
BIN THERMOMETERS







Table 1. Bin Inspection Equipment

1. Duffle Bag Army surplus
2. Man-in-Bin sign magnetic
3. Safety Belt
4. Safety Ropes 60-75 feet
5. Bin Lettering Guide resembles the spokes of a wheel made from 5-36" pieces of lath, spaced 720 apart by
means of string stapled to each lath
6. Spray Paint for lettering the inside of bin during initial inspection
7. 5-Foot Compartmentalized Grain Trier for moisture and insect probes
8. Temperature Probe
a. Bin Thermometer
b. T-Handle
c. 3-Foot Extension (threaded type)
9. Vise Grips used with temperature probes to ensure probes are not lost
10. Screwdriver for opening moisture cans
11. Moisture Sample Containers (use one quart bottles or metal cans)
12. Sample Collectors (3' x 7' canvas cloth or metal gutter)
13. Sample Bags for carrying moisture samples
14. Plastic Box with pens and tags
15. Clipboard with forms
16. Grain Sieves
a. 1/12-inch round hole sieve or 1/8" hardware cloth soldered on cake pan
b. 3/16-inch round hole sieve or 1/4" hardware cloth soldered on cake pan
c. solid bottom pan
17. Moisture Meter Dole 400, Steinlite, Motomco Model 919, etc.
18. Dust Masks
19. Rawhide Bootlace for holding equipment together and for attaching vise grips and screwdriver to safety belt
20. Boerner Divider


N

Sampling plans
There are several sampling patterns that may be
utilized to locate damaged grain hot spots or pest
populations. A minimum sampling plan for round
and flat storage is explained below:
o* X
Full upright bin
1. A north-south orientation of sampling points
is suggested to ensure a sampling of grain in
areas having potentially the most extreme
temperature variation.
2. Full length trier sample at 10" angle.
Sample 1 foot from north and south wall S
and halfway between center and wall
(Figure 3). Moisture Probe Position
3. Horizontal trier sample 3 inches below grain Deep Cup Sample
surface in an undisturbed area (Figure 3). X Temperature Probe Position
4. Deep cup sample (265 g size) at surface and o Horizontal Trier Sample (Undisturbed area)
at 3-foot intervals from the grain surface to H Hotch Opening
the bottom (Figure 3). Figure 3. Minimum sampling plan for full upright bin.








0o o


* *'


* Moisture Probe Position
* Deep Cup Sample
X Temperature Probe Position
0 Horizontal Trier Sample (Undisturbed area)


Maximum sampling plan
The more representative samples that are taken,
the higher the accuracy of the measurement. The
following procedure is suggested whenever possible.
The grain surface of circular bins should be divided
into five equal "pies" for bins under 24 feet and 10
equal "pies" for bins over 24 feet in diameter (Fig-
ure 5). Sampling distance from bin center to points
of equal volume are shown in Table 2. Possible
probe sites exist where equal diameter volumes and
pie volumes intersect. The number of samples to
take for temperature and moisture determination
are listed in Table 3.


Figure 4. Minimum sampling plan for flat storage.


Flat storage
A peak or high point in the grain mass should be
considered as the center of a bin. Otherwise, the
mid-point will be the actual center of the grain
bulk. The sampler should exercise his judgment to
obtain a surface trier sample and at least five other
trier samples, or four other trier samples plus the
deep cup samples if depth allows. The following top
view diagrams (Figure 4) can serve as guides for
possible probe sites.


Table 3. The number of samples required to adequately
sample circular bins for temperature and moisture.

Number of samples per Bin
Temperature Moisture
Bin Probes Probes
Diameter Shallow Deep Shallow Deep

Less than 24 ft 3 1* 5
Greater than
24 ft 1* 5 3 10
*In bin center


Table 2. Distance from the center of the bin to the sample point associated with five equal volumes of grain for several sizes of
grain bins.

Bin Distance from Center of Bin to Point of Sampling-Ft.
Diameter (0.1580)* (0.2740)* (0.3535)* (0.4185)* (0.4745)*
(ft) 1 2 3 4 5

15 2.37 4.11 5.31 6.28 7.12
18 2.85 4.93 6.37 7.54 8.54
21 3.32 5.76 7.43 8.79 9.97

24 3.79 6.58 8.49 10.05 11.39
27 4.27 7.40 9.55 11.30 12.81
30 4.74 8.22 10.61 12.56 14.24

33 5.22 9.04 11.67 13.81 15.66
36 5.69 9.86 12.73 15.07 17.08
39 6.16 10.69 13.79 16.32 18.51

42 6.64 11.51 14.85 17.58 19.93
48 7.58 13.15 16.97 20.09 22.78
60 9.48 16.44 21.21 25.11 28.47
*Multiply this number by the Bin Diameter to determine the distance from the center of the bin to the Point of
Sampling.














FLORIDA GRAIN BIN INSPECTION


Cooperator's Name____


Date


Bin Number Bin Diameter Crop


Sample Information -
Moisture Temperature
Sample Sample
Depth Depth
Probe of Can % of Degrees
ID* Probe No. Mo. Probe F





















*First Letter = Radius used for sample
Second Letter = Indicates a Temperature Probe
Numbers) Probe distance in feet from Bin Center
Grain Position


5 -


Scout Comments:


TOP VIEW OF BIN
F


Use the 5 solid lines for bins under 24 feet in diameter
Use both the 5 solid and 5 broken lines for bins over
24 feet in diameter
S= Moisture Probe Position
G = Hatch Position
X Temperature Probe Position


- 5'

-10'

-15'


Signature


Figure 5. Florida grain bin inspection form.


10'-

15'-









Bin Letter Guide

The bin lettering guide can be constructed with five pieces of light
wood or metal and a nut and bolt. A hole the diameter of the bolt
should be drilled two feet from the end of each letter guide arm.
The bolt and nut should be tightened only enough to allow the guide
to be folded during transportation. When unfolded in the center of
grain bin, the ends of the guide arms should be 2' 5/16" apart.


Five Guide Arms


I 2-
I~ 1I


Attach with a nut and bolt


Bin Lettering Guide Unfolded


I --I2' 3/16"-


Figure 6. Bin lettering guide.









Cooperator's Name

Address

(Fill in data for each bin)

Bin Number


Location of Bin

Size of Bin X =
diameter height to eave capacity in bushel

Expected date of fill
month day

Number of months grain is expected to be in storage

Drying System

In Bin Drying Out of Bin Drying

Unheated air Batch
Heated air Continuous Flow


Number and size of aeration fans, if any

Type of Grain: Corn: Soybeans Wheat


Will grain bin wall and floor be sprayed with insecticide prior to

filling? yes ___ no ___. If yes, what insecticide will be applied




Is there a stirring device? ___ Grain spreader? Cleaner?


Other relevant data that IPM personnel should know.













Figure 7. Grain bin history form.








A bin lettering guide (Figure 6) can be used at bin
center in order to establish possible probing points.
The guide should be unfolded so that each of the five
spokes is 720 apart. With the guide in place, cen-
tered on the top of the grain, a can of spray paint can
be used to mark the bin with letters. The roof of the
bin or the wall near the roof should be lettered with
paint as indicated in Figure 5. This procedure
should be done on the first visit.

A bin inspection form (Figure 5) should be filled
out prior to entering the bin. A bin history and loca-
tion form is always useful (Figure 7).


Overfilled bins
One of the most important considerations in the
inspection and subsequent maintenance of quality is
the grain level within the bin. Bins are often filled
beyond the rated capacity by peaking the grain and
at the same time filling it to the eaves. This practice
results in sampling and inspection problems because
there is insufficient room between the grain and the


Figure 8. Sampling an overtilled bin.


bin roof to work. A sample taken while outside
from the bin wall door, roof door, or roof cap may be
the only point accessible for the deep bin cup probe
(Figure 8). In such cases, the following procedure is
recommended:
1. Sample in the center at intervals as deep as
possible using the deep cup probe. Temperature
readings should be obtained at regular points and
intervals.
2. If a roof door can be opened, sample 1 foot
from the wall with the grain trier and as far from
center as possible.
3. Using the deep cup probe, sample at an
angle with several extensions in a north and south
direction. Reach the bin wall if possible at two to
three depths.


Procedures

Temperature
The temperature probe should be left in place
while making a moisture probe with the grain trier
to allow enough time for the thermometer to reach
equilibrium within the grain mass. The tempera-
tures should be recorded on the grain bin inspec-
tion form (Figure 5). It is important that the exten-
sions are well connected. The probe should not be
twisted counterclockwise because this will discon-
nect sections and leave a probe buried in the grain
mass which could damage unloading equipment.
Vise grips can be used to hold the probe sections
and prevent disconnection in the grain mass.


Moisture
The most accurate means of determining mois-
ture content is the oven method. In this system, a
known weight of grain is subjected to very high
temperatures for several days until all of the water
has been removed from the grain. The moisture
content of the sample may be determined by using
the following equation:
%Moisture Content = (Initial sample weight -
Final sample weight) x 100
(wet basis) Initial sample weight
However, the time required to obtain a moisture
content reading using the oven method is too slow
for most farm applications. Therefore, electronic
grain moisture meters are more practical.

Most moisture meters determine moisture con-
tent indirectly by measuring the electrical proper-
ties of the grain. Electrical properties of grain







change with moisture content and temperature for
a given grain type. Generally, more expensive
moisture meters measure moisture content more
accurately and many make automatic adjustments
for grain temperatures. Less expensive moisture
meters usually require some adjustments for tem-
perature. At least 250 grams of grain are needed to
test moisture with most meters.

It is advisable that the less expensive meters be
occasionally compared periodically to known stan-
dards to minimize errors. For example, if a meter
is known to "read 1 point high" consistently, correc-
tive actions can be taken. Likewise, several read-
ings should be taken for each sample so as to re-
duce the risk of error.

Electrical moisture meters operate under the as-
sumption that the moisture content of the grain is
uniformly distributed throughout the sample. This
is not the case especially when grain is first re-
moved from a drier. Once the moisture in the grain
has equilibrated within the kernel, a more accurate
moisture reading may be obtained. As indicated
above, when a bin of grain is examined, it is impor-
tant that the grain has cooled and that it has been
a few days since drying. Farmers sometimes asso-
ciate this apparent change in moisture with opera-
tion of the aeration fan. However, aeration does
not generally produce any significant changes in
the moisture content of the grain.


Insects, test weight and dockage
The grain sample should be placed in the top
hopper of a Boerfer divider and allowed to pour
down the sides of the cone located directly under
the opening, The sample should be divided into two
equal streams just before reaching the bottom pans.
To arrive at the 1-1/2 quart working sample re-
quired for analysis, the large samples must be di-
vided two or three times. The test weight of the
grain can determined with a Boerner weight per
bushel tester. The grain must be allowed to flow
freely from a filling device into a 1-quart dry mea-
sure bucket. Excess grain will flow over on all sides
into an overflow pan. The bucket can then be care-
fully leveled by three quick, even strokes of a hard-
wood strike-off stick held upright across the bucket
top. The bucket can then be weighed on the associ-
ated balance. Care should be exercised not to
shake this apparatus during this procedure since
this will cause compaction of the grain and result in
inaccurate readings. The test weight is the density
of the grain in pounds per unit volume (1 bushel).


Two sieves are needed for the separation of whole
kernels from dockage, insects and broken pieces.
These are the 3/16-inch round sieve and the 1/12-
inch fine seed sieve. The working sample should be
separated into four equal batches and each batch
screened separately. The sieve and bottom pan
should be shaken in a side to side direction (about
10-inch movements) 30 times. Different portions
will be collected as dockage or whole clean kernels
depending on the type of grain. Kernels stuck in the
sieve will remain with the retained portion.

Various types of balances are needed to weigh
whole grain, dockage and portions for moisture test-
ing. For damage determination, a scale with 0.01 g
accuracy is recommended, while a scale with 0.1 g
accuracy is adequate for other tests.

Sample pans are also required for collecting dock-
age portions, subdividing samples for sieving, and so
on. Triangular sample pans are convenient for
pouring the grain into containers and testing equip-
ment.


Pathogens
Samples of stored grain collected for pathogen
identification should contain at least 100 seeds.
Seeds should be selected that show the full range of
variability from normal in appearance to the ex-
tremely moldy condition (if present). Samples
should be appropriately marked with grower name,
bin number, location of sample from within the bin,
date and degree of problem. Place the seeds in pa-
per sacks and deliver them to a preassigned labora-
tory for identification. Samples kept in completely
saturated atmosphere become colonized by sapro-
phytes (plants that live on dead or decaying organic
matter) that "outgrow" the causal organism. This is
the reason for requesting the full range of variability
of seed selected and the placement in paper bags
rather than sealed plastic bags.

Samples received at the laboratory, depending on
their condition, may be examined directly under the
microscope, placed on culture media, or placed in a
moisture chamber for a few days. Once fungal iden-
tification is made, additional tests may be desired if
the fungus is one that is likely to have produced my-
cotoxins. The tests for mycotoxin determination
vary in their qualitative and quantitative abilities.
These range from the black light test (ultraviolet
light) to minicolumn to thin layer chromatography.
Some of the tests may be rather time consuming and
costly, and not performed by all laboratories.










FIELD SAMPLE



- Divide


NOTE Insects




OFF ODORS WORKING


EXCESS: Sieve
and NOTE Inse


Collect Insects ----Sieve 12/640







INSECT COUNT WHOLE
CORN


IDAMAGES-


100 q \W n


CORN


250 g MOISTURE
SAMPLE TEST


UART TEST WEIGHT
I L----


bottom
sievings


-Dockage


remove foreign
materials


PERCENT Weigh
BCFM Wei


RODENT
PELLETS


Figure 9. Detailed sample flow chart for corn.


EXCESS: Sieve


land








Analysis of shelled corn (Figc : =J
The field collected composite sample and specific
bottle samples) should be evaluated similarly, ex-
cept that the bottle sample will not need to be di-
vided. With the bottle sample, the 250 g portion
used for moisture testing must to be re-added to the
original portion after use in order to maintain an ad-
equate sample size sufficient for the remaining tests.

A large enough working sample of corn should be
divided out to make the moisture test and test
weight determination (1-1/2 quart minimum).
Excess portions can be screened and insect species
can be identified and recorded. The odor of the
sample (musty, mold, rodent urine, for example)
should be noted.

The moisture content should be tested using the
proper grain quantity (usually 250 g) needed for the
type of moisture meter used. After the test, this
portion should be returned to the excess portions.

The test weight should be determined to the near-
est 0.1 of a pound per bushel. The overflow should
be added to the excess portion. The one quart
sample should be saved for the BCFM (broken corn
and foreign material) determination.

A 3/16-inch round hole sieve must be used to
determine BCFM. About one-fourth of the sample
should be sieved each time. The sieve must be
shaken 30 times using a side to side motion of 10
inches.

The corn remaining on top of the sieve should be
hand picked to remove all foreign materials. The
foreign materials should be added to the portion that
passed through the sieve and weighed to determine
the percent by weight BCFM.

The material that has passed through the 3/16-
inch sieve should be examined carefully for insects.
The number of each species should be recorded. In
addition, any rodent pellets found in the BCFM por-
tion should be counted and recorded.

All corn remaining on top of the 3/16-inch sieve is
considered whole corn. This should be weighed to
determine percent by weight BCFM. The whole corn
should be checked for large insects that did not pass
through the 3/16-inch sieve and the number and spe-
cies of insects should be recorded. A 100 g sample of
whole corn should be weighed out for damage deter-
minations.


Analysis of wheat (Figure 10)
The field collected composite sample and specific
bottle samples) should be evaluated similarly, except
that the bottle sample will not need to be divided.
With the bottle sample, the 250 g portion used for
moisture testing must to be re-added to the original
portion after use in order to maintain an adequate
sample size sufficient for the remaining tests.

A large enough working sample of wheat should be
divided out to make the moisture test and test Weight
determination (1-1/2 quart minimum). Excess por-
tions can be screened and insect species can be iden-
tified and recorded. The odor of the sample (musty,
mold, rodent urine, for example) should be noted.

The moisture content should be tested using the
proper grain quantity (usually 250 g) needed for the
type of moisture meter used. After the test, this por-
tion should be returned to the excess portions.

A 1000 g working sample should weighed out.
Any off odors should be noted. Extra wheat should be
added to excess portions.

For sieving, a 1/12-inch round hole sieve should be
assembled onto a bottom pan and then a 3/16-inch
round sieve should be placed on top of the 1/12-inch
sieve. About one-fourth of the sample should be
sieved each time. Shake the sieve 30 times using a
side to side motion of 10 inches.

After the sample has been sieved, the material
remaining on top of the 12/64-inch round sieve and
the material that passed through the 1/12-inch sieve
should be combined. Any foreign materials (stones,
chaff, stalks, etc.) that remain above the 1/12-inch
round sieve should be hand-picked and combined
with other sievings. The materials should be
weighed to determine the percent of dockage in the
sample. The percent dockage is equivalent to the
weight of dockage in grams divided by 10.

The dockage should be carefully examined for
insects. The number of each species should be
recorded. In addition, any rodent pellets found in
this portion should be counted and recorded.

All wheat remaining above the 1/12-inch round
sieve is considered dockage free, clean wheat. The
clean wheat should be checked for large insects that
did not through pass the 1/12-inch sieve and the
number and species of insects should be recorded.










FIELD SAMPLE


WHEAT


EXCESS: Sieve Divide
and NOTE Insects


S250 g MOISTURE
TEST



EXCESS: Sieve
and NOTE Insects 1000 gOFF ODORS


Sieve


a. 12/64 0


above sieve


Dockage


Collect Insects-



INSECT COUNT


b. 1/12


foreign materials


in bottom pan
c. bottom pan-------


CLEAN WHEAT








DAMAGESi- 25dg TEST WEIGHT







Figure 10. Detailed sample flow chart for wheat.


PERCENT
DOCKAGE








The test weight should be determined to the
nearest 0.1 of a pound per bushel using the clean
wheat portion. In addition, a 100 g sample of the
clean wheat should be weighed out for damage
determinations.


Summary
This publication has discussed methods and
equipment for sampling grains and the use of sam-
pling to properly manage grain in storage. Success-
ful storage of grain begins with preharvest manage-


ment practices to insure proper grain bin sanitation
and insect control followed by proper drying of the
grain. Aeration should be employed to help main-
tain grain quality in storage to insure uniform tem-
perature throughout the grain mass and to prevent
moisture migration. The grain must be monitored
during storage to head off storage problems. Con-
sistent and timely sampling of stored grain along
with analysis and proper interpretation of test
results can detect existing or potential problems
before considerable damage has occurred.


COOPERATIVE EXTENSION SERVICE, UNIVERSITY OF FLORIDA, INSTITUTE OF FOOD AND AGRICULTURAL SCIENCES, John T. Woeste,
Director, in cooperation with the United States Department of Agriculture, publishes this information to further the purpose of the May 8 and June
30,1914 Acts of Congress; and is authorized to provide research, educational information and other services only to individuals and institutions that
function without regard to race, color, sex, age, handicap or national origin. Single copies of extension publications (excluding 4-H and youth
publications) are available free to Florida residents from county extension offices. Information on bulk rates or copies for out-of-state purchasers
is available from C.M. Hinton, Publications Distribution Center, IFAS Building 664, University of Florida, Gainesville, Florida32611. Before publicizing
this publication, editors should contact this address to determine availability. Printed 4/92.




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