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Maximizing on-farm storage

The dramatic increase in Mid-South acres of “yellow gold” in recent years has filled the rural landscape with a corresponding proliferation of “silver monuments,” says Mike Buschermohle.

The flood tide of corn at harvest has resulted “in long lines of trucks waiting to unload at elevators, horrible shortages of barges for river transport, sometimes wild swings in basis, and other factors that have spurred intense interest in on-farm storage,” the University of Tennessee professor of biosystems engineering said at a recent grain storage workshop at Webb, Miss., sponsored by the Mississippi State University Extension Service, Delta Rice Services, Bunge North America, and the GSI Group.

But, he cautions, anyone thinking about making the hefty investment in new grain storage facilities should first ask several important questions.

• Do I really want this?

• Will it help my marketing strategy?

• Will I be a good manager of this storage?

• Will I be willing to put forth the effort needed to manage this storage?

• What capacity do I need?

• Will my need be short term or long term?

• Do I plan to add irrigation/more irrigation to my farm, affecting the volume of grain produced?

• How much grain do I want to store and how much will I take to an elevator?

• How many different crops will I grow?

• Will I need to segregate GMOs from non-GMOs?

• What are my grain handling/hauling capabilities?

• Do I have adequate combining equipment, and do I plan to purchase more?

“The more thorough your planning on the front end,” Buschermohle says, “the better your facilities will be and the fewer bottlenecks you’ll have once they’re in use.

“You need to know your expected total capacity needs for not just the year you construct a bin, but for what you expect in the future.”

An 8-row combine, running at 4 mph and cutting 175-bushel corn will harvest almost 18,000 bushels in a 10-hour day, he notes. That grain will fill an 18-foot diameter bin to a depth of 88 feet, a 41-foot bin to a depth of 17 feet, and a 48-foot diameter bin to a depth of 10 feet.

With 1 bushel of corn requiring about 1.25 cubic feet of storage space, a 30-foot diameter bin will hold 11,643 bushels, a 42-foot bin, 25,000 bushels.

A complete system for grain storage, Buschermohle says, generally consists of receiving and elevator facilities, wet holding areas, drying equipment, conveying and aerating equipment, and load-out facilities.

“If you let corn dry down in the field, it can cut costs, but weather conditions add an element of uncertainty, and being able to dry in storage allows you to manipulate the harvest window.

“Dryers add flexibility to a storage operation, allowing you to get in the field for harvest earlier and to harvest at higher moisture content.”

At 20 percent moisture, he says, 74,000 pounds of corn that have just gone into a trailer from the combine will have 15,000 pounds of moisture.

“Regardless of whether you dry corn on-farm or take it to the elevator, you’re going to lose about 5.8 percent of that water to shrinkage.”

Maintaining the quality of grain in storage requires an integrated approach that incorporates a number of tools and practices, Buschermohle says.

Drying systems that may be utilized include:

• Natural air for in-bin, continuous flow drying. “This results in lower-cost drying and high quality grain.” With a 1.5 cubic foot per minute airflow per bushel, it takes 5.5 days to dry 17,850 bushels in a 42-foot bin; at 1 cfm, it takes 8.3 days.

• In-bin shallow batch drying: With grain at a depth of 4 feet and 140-degree air at 14 cfm, drying time is about 6 hours; for 8 cfm, about 10 hours. “This method takes a tremendous amount of fan power and requires a stirrer or other device.”

• Continuous flow drying, with 180-200 degree temperatures and 50-100 cfm airflow, can dry about 900 bushels per hour from 20 percent down to 15 percent.

Dryeration and in-bin cooling can also increase drying capacity and reduce fuel costs, Buschermohle says.

“Proper airflow is critical for the most effective drying of corn. The capacity to dry the grain and cool it after drying is a function of fan size/cubic feet per minute of airflow, so you need to be sure you have adequate fan capacity for your bins.”

While there are cost estimate calculators available for drying (Iowa State University has one), “the best way to determine costs is to keep records of the various expenses for your own operation,” Buschermohle says.

Estimates from the Midwest are 5.1 cents per bushel for natural air drying; 11 cents for low temperature (10 degrees) heat drying; 13.5 cents for in-bin batch drying; 17.9 cents for continuous flow drying with recirculating air; and 20.3 cents for continuous flow without recirculating air. “Propane price will be a big factor in your drying costs,” he says.

“When corn comes out of the dryer, the quality is as good as it’s going to be,” Buschermohle says. “Grain quality won’t improve during storage; at best, quality can only be maintained. It’s up to you to do everything possible to keep that quality — if you don’t, things can get worse.”

Grain moisture content and temperature interact to affect storage risk, he notes. “Even the best management practices won’t keep grain from spoiling if moisture content and temperature are too high. As little as a 0.5 percent moisture increase can mean the difference between safe storage and a damaging invasion by fungi.”

Most grain drying systems were developed in the Midwest, Buschermohle says, “and conditions in the Mid-South, as every farmer knows, are markedly different, particularly in hurricane years or years with abnormally wet harvest periods.”

Corn in the field that is drought-stressed can also start a chain of conditions that are favorable to development of aflatoxin, or losses caused by other molds, which can increase during storage and result in significant price discounts or even rejection of the corn by the elevator. “You can’t hide many things at the elevator these days,” he says.

“In winter, you can store grain at a higher moisture content than in summer. If you plan to sell during the September-October period, you should store at 14 percent moisture; during November-March, 15 percent; April-May, 14 percent; and June-August, 13 percent.”

To help preserve grain quality in storage, Buschermohle recommends the SLAM program: Sanitation, Loading, Aeration, and Monitoring.

• Remove all old grain from combines, truck beds, grain carts, bins, augers, and other equipment used for harvesting/transportation/storage. “Even a small amount of insect-infested or moldy grain left over from a previous harvest can contaminate a bin of newly-harvested grain.”

• Keep weeds down around bins to control insects and rodents.

• Inspect bins for holes, missing bolts, and rust, and caulk, patch, and make needed repairs to prevent water/rodent damage.

• Remove all debris from fans, exhaust vents, and aeration ducts.

• After cleaning and repairing, sanitize walls, floors, under-floor areas, and roof areas inside and out with an approved residual spray.

Grain should be as clean as possible before loading it into bins in order to reduce trash and fines. “Good quality, clean, sound grain is much easier to store and market than cracked, broken grain.”

Broken grain and foreign material, or fines, can accumulate in pockets in the bin that restrict airflow and also create a haven for molds and insects. “Broken kernels will mold three to four times faster than whole kernels, and are more susceptible to insect attack.

“If you have a lot of trash in your grain, it can form an extremely dense core in the bin, preventing even airflow, and resulting in pockets of higher moisture, spoilage, grain quality loss, and in general, a lot of headaches.

To help insure that only high quality grain goes into storage, Buschermohle says it’s important to (1) properly adjust combines to manufacturer specifications in order to minimize grain damage during harvest and maximize removal of trash and fines; (2) operate augers at full capacity to reduce wear and grain breakage; (3) don’t mix new grain with old, “because this will be a potential source of mold and insect infestation for the new grain; and (4) clean grain before loading into storage bins to reduce foreign material and improve storability.”

“Unfortunately,” he says, “cleaned grain may have no greater market value, and fines add weight to marketable grain. Unless fines are causing lower grades or serious storage problems, cash grain farmers may lose money by cleaning grain, unless the cleanings can be sold to a livestock producer or gain elevator.

“Don’t overfill the bin; that hampers airflow and creates problems. We like to see a level top surface on the grain in order to facilitate airflow. You will have to operate a fan about 50 percent longer to cool an overfilled bin, compared to leveling the grain and filling only to the eave. Peaking the grain also makes it more difficult and dangerous to monitor during storage.”

Know the moisture content of the grain in storage, Buschermohle says. “If you use hand-held moisture meters, take grain samples to an elevator and compare their readings with your meters in order to calibrate them.”

Millions of bushels of dry grain spoil each year because temperatures are not properly controlled in storage, he says.

“As outside air starts to cool, aeration can be a very powerful tool to prevent moisture migration in the grain, which can create conditions favorable to mold and insects, and can cause a crust of 6 inches to 2 feet or more on top of the grain. In summer, moisture migration is just the reverse, and can cause pockets of spoiled grain on the bottom of the bin.”

Aeration can greatly improve the storability of grain by changing its temperature in response to seasonal temperature changes, Buschermohle says.

Target storage temperatures: September/October, 55-65 degrees; November, 40-50 degrees; December/February, 35-45 degrees; April, 60 degrees.

“Costs of aeration are more than repaid in grain quality,” he says.

Grain temperature should be monitored frequently to know when to turn fans on and off. Electronic controllers are available to help make these decisions.

“Failing to monitor grain conditions throughout the entire storage period is a mistake many producers make,” Buschermohle says. “Regular inspections are essential if mold and insect activity are to be detected early. A small area that starts to heat or otherwise get out of condition can quality get out of control and spread within the bin.”

How often grain needs to be check will vary with the time of year, initial condition of the grain, and how often it’s aerated. Generally, he says, it should be inspected at least once a month during the winter and every two weeks during the spring, summer, and fall.

“Grain temperatures should be checked and recorded during each inspection; without temperature records, it’s difficult to tell whether elevated grain temperatures are caused by normally-occurring outside temperatures or by heating due to mold activity.”

A deep bin probe should be used to obtain samples at different locations in the bin to determine moisture content, amount of trash and fines, and the general condition of the grain. “Check bins frequently for insects; populations can explode within weeks under the right conditions. Put out traps for rodent control.”

Buschermohle suggests doing a “sniff test” every two weeks in the summer and once a month at other times to detect musty or sour odors that can indicate spoilage.

“All these are problems you need to catch before they get out of hand. We’ve seen far too many instances of producers thinking once they get grain in storage their job is over.”

And, he cautions, “Always be aware of dangers related to bins and have safety procedures in place.”

Buschermohle says the first time he saw polybags being used for in-the-field grain storage in Tennessee, “I thought, ‘This is nuts!’

“But a number of farmers have used them effectively as quick fix storage. Just be aware that these systems were developed for colder climates; if you use them, make sure the grain going into them is dry and that you do a good job of aeration.”


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