High moisture grain may be chemically preserved byadding an organic acid to inhibit mold growth. This methodmay provide an acceptable alternative to drying dependingon the price and availabil ity of fuel during the harvest sea-son. To successfully employ this method of grain preserva-tion, the advantages, disadvantages, and management proce-dures should be understood.

Principler of Grain Storage

The key to successfully storing grain for extendedperiods of time is to control mold growth. Molds requireadequate moisture, food, and environmental conditions tosurvive and grow. lf any one of these conditions is unsatis-factory, mold growth will be hindered severely or stoppedcompletely.

The traditional method for preventing mold growthhas been to lower the moisture content of the grain to safestorage levels by drying. However, fuel shortages may limitthe amount of corn that can be dried using batch-in-bin,portable batch and continuous flow driers.

The second method of mold prevention involvesrestricting the available food for growth. However, cornrepresents the food supply for the mold in the form of f inematerial, trash, and broken, cracked and whole kernels,Sti l l , the grain should be cleaned before it is placed in thebin in order to reduce the mold's readily available foodsupply.

The third method of mold prevention, removing afavorable environment for mold growth, consists of l imitingacceptable levels of temperature, oxygen, and pH. lf thetemperature could be kept below 40oF, mold growth wouldbe minimized. But, temperature in Kentucky during theharvest seasons are usually much higher than this. lf oxygenlevels were reduced to low levels, mold growth would cease.High moisture corn storage systems operate on this princi-ple. Also, if the pH of the grain is lower than approximately4.5, mold growth is minimized. By adding acid unti l the pHof the grain is below 4.5, grain may be stored for indefiniteperiods of t ime.

Advantages of Acid Treatment

The principle advantage of chemical preservatives isthat very little energy is required to treat the grain. There-fore, the producer is not t ied to the availabil ity of fuel inorder to succesfully store his crop. Limited researctrindicates that the feed efficiency of treated grain may befavorably compared to ensiled high moisture grain, with thetreated grain not incurring fermentation losses.

The cost of the equipment used to apply acid is muchless than the cost of most types of dryers. Therefore, a lowinitial investment is another advantage to the producer.Furthermore, grain can be harvested and treated at almostany rate, removing a possible "bottleneck" created by a lowcapacity dryer.

Other advantages, such as early harvest date, hdrvest-ing at high moisture, etc., are common to other storagemethods as well.

Diradvantages of Acid Treatment

The disadvantages of acid treatment lie primarily inthree areas, those of marketing, bin and handling equip-ment corrosion, and cost.

Grain that has been treated with chemical preserva-tives may no longer be sold through the normal marketingchannels and must be fed to livestock. For this reason, thefarmer who treats his grain is l imiting the source of his grainsales to livestock feeding operations. Treated grain cannotbe used for seed because it will not germinate, and it cannotbe used for human consumption.

Treated grain also corrodes metal grain bins. Thereare various bin wall coatings available on the market whichwill reduce this corrosion, but the costs of these productshave been prohibitive in many instances. Equipment usedto handle treated grain is also subject to corrosion. Becauseof corrosion problerns, a producer who plans to storetreated grain should add the cost of reduced bin and hand-ling equipment life expectancy to the overall cost of acidapplication.

rssued in furtherance of cooperative Extension work, acts of M_ay.8 and June 30, 19_14, in-cooperation wtth the U,s. Depaltment of Agriculture.charles E. Barnhart, Director of cooperative Extmsion seivice, -u"niversity-;-i

The cost of applying acid to grain depends on manyfactors, including the initial moisture content of the grain,

the length of time it is to be stored, the cost of the acid,and the quantity of grain that is to be treated. Tables 1 and2 give a detailed economic comparison of various nethodsused to preserve and store grain. Among the assumptionsmade by the comparison are:

1. All corn produced will be fed on the farm.2. The system is designed to complete the corn

harvest as rapidly as is economically feasible.3. All new equipment is purchased at prices

quoted by leading rnanufacturers.Corn harvesting equipnnnt is already available.Depreciation costs for the bins used for storingacid-treated corn were asurned to be twice thecost of the same bin used for dry corn.The cost of acid preservative is 24tper pound.The initial moisture for the grain is 25% while afinal moisture content is 15% when drying thegrain.

Note in Table 2 that the costs of handling high mois-ture corn are reduced by 5 cents per bushel, assuming anincrease in feed efficiency of 4 percent.

The economic analysis concluded that lower pricesfor acid would enable grain preservatives to compete effec-tively with the elevator, Harvestor, and portable batchdryers, but that acid prices below 10dper pound would benecessary before this system would compete with thebatch-in-bin dryers.

However, because of a possible fuel shortage andbecause commercial application of acid is a reasonably newpractice, the relative cost of treating grain with acid maychange radically in the near future.

Methodr and Management

Generally, the acids applied to grain as preservatives

are propionic, acetic, or combinations of these trrvo. Propi-onic acid has become the dominant acid used for commer-cial treatment of grain.

The key to succesful grain storage with acid treat-ment is to apply enoudl *id unifornily ouet the grain.

Should some grain either get a low dosage or happen to

AEN_21

miss treatment altogether, "hot spots" in the bin mayresult. The typical method of application is to use a meter-ing device which sprays acid on the grain as it passesthrough an auger.

Consult the recommendations of the acid manufac-turer for application rates. Suggested guidelines fromseveral companies are given in Table 3. The higher the mois-ture content of the corn, the larger the amount of acid thatwill have to be applied. Daily checking of grain moisture asthe grain is harvested is necessary if acid is to be appliedcorrectly. Also, greater amounts of acid will have to beapplied if the corn is to be stored for long periods of time.Be sure to chec* grain regularly for signs of heating ormold. Retreatment may be necessary to hold grain over thesummer months.

With regard to insects, use the same recommendedprecautions and methods of control as for dried grain.Placing clean grain in storage is always beneficial, whether itbe to retard insect developrnent or decrease mold activity.Aeration of the treated grain is also recommended.

Treated grain has been stored in the open and some-times covered with plastic. This might prove satisfactory asa temporary emergency method but because of the highrainfalls in Kentucky and because the grain is exposed torodents, birds, etc., this approach to storage could result inexcessive losses and is not recommended.

Safety

Safety begins with application of the acid. Avoidbreathing the vapon of the acids. Grain should be treated inopen, well-ventilated areas. People should avoid enteringclosed areas or bins where treated grain is stored. Becausethe acids are flammable, do not treat grain near heatingdevices or open flame. Don't smoke near the applicator.Safety equipment such as gloves, aprons, goggles, and shoesshould be worn. They should be made of rubber or plastic

to prevent absorption into the skin.lf the skin or eyes have contact with the acid, wash

with large quantities of water. Change clothes if acid isspil led on them. lf acid is somehow swallowed, wash outthe mouth with water. Drink milk mixed with raw eggwhites to neutralize the acid. Safety is always a necessityduring the acid treatment of grain.

4.5.

6.7.

Table 1. Summary of CosG for Gonditioning Storing and Handling GornUnder Alternate Syrtem3, in Gentl Per Bushel*

SYSTEM

COSTSEar cornin crib

Barch-in-Bindryer

PortaHeBatdldryer Hawesbre

Acidin bin

Acid under Acid, noplstic storagp Elevator

Annual fixed costsTotal operating costsTotal field losesTotal miscellaneous costsTotal cost per bushel

Annual fixed costsTotal operating costsTotal field lossesTotal miscel I aneous costsTotal cost per bushel

Annual fixed costsTotal operating costsTotal field losesTotal miscellaneous costsTotal cost per bushel

Annual fixed costsTotal operating costsTotal field losesTotal miscellaneous costsTotal cost per bushel

13.704.004.50-0-

22.20

11.204.005.90-o.

21.10

10.104.009.00-0-

23.10

9.804.@9.00-0-

22.80

19.502.83.80.63

23.76

12.703.55-0-

.6316.88

7.703.55.50.63

12.38

7.103.55.50.63

11.78

28.802.il.80.63

32.77

16.303.55-0-.63

20.8

10.103.55.50.63

14.78

9.503.55.50.63

14.18

14.4014.70

.20-o-'

29.30

8.5014.70

.20-()-

23.40

4.3014.70

. 1 0-0-

1 9 . 1 0

3.6014.70

. 1 0-0"

18.40

7.8014.70

.201.25

23.95

4.1014.70

.201.25

20.25

1.3014.70

. 1 01.25

17.35

.7014.70

. 1 01.25

16.7s

-0-16.50

.206.30

23.00

-0-16.50

.206.30

23.00

-0-16.50

.506.30

23.30

-0-16.50

.506.30

23.30

5,(X)O Bushels28.40 17.20-0- 14.70.30 .20

1.25 -0-29.95 32.10

10,0()(1BuCrelr19.80 13.20-0- 14.70.30 .20

1.25 -0-21.35 28.10

50,000 Burhelr17.00 9.90-0- 14.70.20 .10

1.25 -0-18.45 24.70

100,000 BuCtels15.50 9.20-0- 14.70.20 .10

1.25 -0-16.95 24.W

'Hdl. G. E" L. D. HCl, lnd E. E. rhtfi.ld, 1973. '?ioFlonldlodc &ld fd Hhhuol.nrF con P|t omdon." AaAE FFr i|o.733i2, Fo. prt.ri.r'on|tth.1973 AnnEl M.tin!of th. Arl.rlc.n Sod.ry of Aadculiunl Engl|EF, L.nnlirtr, Knructy.

b+\t

AEN-21

Tabls 2. Costs Per Bushel for Handling, Conditioning, and Storing Corna*

SYSTEM

ANNUALVOLUME (BU.}

Eal cornin crib

Batch-ln-Bin

drysr

PortaHeBatchdryel

Acidin binb

Acid, nostorageb;c

ElevatorHarvestoreb

Acid underplasticb

cents per bushel5,000

10,0001 5,00020,00030,00040,00050,00075,000

100,000

22.2021.1019.9023.0023.3023.1 023.1 022.9022.80

23.7616.8815.3814,4813.1812.3812.381 1.8811.78

32.7720.4518.7818.5815.8814.6814.7814.381 4 . 1 8

24.9516.3513.2515.3512.651 4 . 1 513.4512,351 1.95

27.1023.1022.5021.7020.7019.9019.701 9 , 1 019.00

24.3018.4016.7015.9014.8014.401 4 . 1 013.6013.40

16.9516.2513.5614.0513.0512.6512.361 1.95I 1 .75

23.0023.0023.3023.3023.3023.3023.3023.3023.30

a Includ€s fixed and variable @st8 of lacil i t ies and operation. lossos in th€ field, and shrink. All system assume thE purchase of new equipmnt snd fsci l i t i88.bcosts of hsndling high-moisture corn are reducad by 5 cents per bushel, assuming an increase in feed Bfficiency of 4 per€nt.cAcid treatment without stomge facil i t les is recommended only in low-rainfall cl imates or during periods of rel6tively low ralnfsll and temperature.

tho Amsrien Society of AgricultuEl Engin€ers, Lexington, Kontucky.

Table 3. Recommended Application Rato, Percent by Weight, for Various Organic Acids for High-Moisture ShelledCorn*

Propionic Acetic(pct.) (pct.)

Storaget ime 3520

Corn moisture content (pct.)

25 30

Celanesea"ChemStor"

Chevron"Ortho Preservative"

British Petroleum"Propcorn"

Union Carbide"Sentry No. 1"

80

100

0.90

0.340.450.70

0.75

0.75

1.20

0.450.700.89

1.00

1.00

1.50

0.700.891.00

1.25

1.25

1.75

1.50

1.50

20 1 year

until Apr. 1until July Iuntil Sept. 1

1 year

1 year

100

100

a Formerly 40 perc,ent propionic and 60 percent ac€tic acid.

*Hall, G, E., L. D. Hall, and E. E. Hatfield, 1973. "Propionic-Acetic Acid for High-Moisture Corn Preservation." ASAE Paper No.7$3'12, For presentation at the 1 973 Annual Meeting of the American Society of Agricultural Engineers, Lexington, Kentucky.

Educational pro$ams coducted by tha Kenwcky Coopentive Extension Senrbe are available to all pertons rcgndles ofr*e, sex, rcligion, national origin, socioeonomic level or gcographlc location.

lssued 8-73,10M