Grain management
By James D. Ritchie

Favorable weather has brought about a bountiful harvest. That means you probably have more grain in your bins than usual. Maintaining grain in storage takes a lot of work--work that starts in the field.

Computer people used to have a phrase: "GIGO," which means "garbage in, garbage out." If you don't put good data into a system, you won't get good information out.

The same can be said about grain storage. Grain coming out of a bin rarely will be better quality than the grain going in; it could be considerably worse.

"An investment in harvesting and maintaining high-quality grain is a win-win situation," said Bill Casady, agricultural engineer with the University of Missouri's crops focus team. "There are no discounts for high-quality grain. Secondly, high-quality grain minimizes the risk of spoilage due to storage molds and insects. It [quality grain] has a longer and more certain storage life than damaged or lower-quality grain."

For Chris Vogel, grain management begins while his crop is still in the field. "I don't begin harvest until corn has field-dried to about 18 percent moisture," said the Saline County, Mo., farmer. "Corn will keep in the bin at 18 percent with fans pushing air through it. But I get concerned if corn is much above 18 percent when we shell it."

Vogel's harvesting strategy was a real money-saver this year. Rising energy prices (especially propane gas) have driven up the cost of artificially drying grain for both farmers and elevators.

"Field drying is a valuable way to dry crops," said Casady. "You don't have to pay Mother Nature, although you may incur some losses in dropped ears or the risk of losing a crop to a storm by waiting."

For much of the southern Corn Belt, that unusually warm, dry weather last spring turned out to be a blessing. The corn crop went in early, and grain began to reach physiological maturity as much as two weeks early this fall.

"That was ideal for field drying," said Casady. "The earlier maturing crop began to dry during the relatively warmer part of the fall. On those hot days in late August and early September, corn may have dried at a rate of about 1 percent per day until the field-dried crop reached about 20 percent moisture--the perfect level to think about drying with only natural air."

Natural air drying works best if you can wait to harvest until moisture content is 20 percent or less, he added. "This takes advantage of the air's ability to remove moisture without adding much heat," Casady said. "You get the best results by maximizing airflow through the grain by using multiple bins and drying grain in relatively shallow layers in the bins."

Remove as much trash and fines as possible as grain goes into the bin and level off the surface of the grain.

"Like electricity, air seeks the path of least resistance," Casady noted. "Air will travel around a peaked pile or a concentration of trash inside a bin, leaving a damp pile. That's where spoilage is most likely to occur. Grain dries from the bottom up in a bin. Grain on top doesn't start drying until the grain below is dry."

Grain dries faster when the air is warm, but the risk of spoilage at the top of the bin also is greater at higher temperatures. Grain aerated earlier in the fall was cooled to average temperatures, which often are pretty warm in some areas. As average outside temperatures become seasonably cooler, the outside of the bin becomes cooler.

"When this happens, there's a larger temperature difference between the grain and the bin walls," said Casady. "It's like a giant sleeve of cold, dense air lining the inside of the bin. As this dense air drops, it pushes warmer air up from the bottom and center of the bin. As that warm, moist air moves upward through the core of grain, it encounters cooler air at the top of the bin, and the moisture it carries condenses--usually right in the center of the bin--onto cooler grain at the top.

"But those cooler temperatures give you a chance to improve the storability of grain," he added. "Cooling grain that is still at 60 degrees F down to 35 or 40 degrees [by running aeration fans] will improve storability of the grain by as much as three times."

"The best approach may be to turn on fans and let them run until the entire mass of grain is cooled," said Casady. "A cooling 'front' passes through grain, in much the same way that a drying front passes through. When the front gets all the way to the top, the temperature of air exiting the top of the bin drops to near the average outside temperature."

He suggests you monitor the air temperature each day to watch for the movement of this cooling front.

"Dry grain to normal market moisture contents [see chart below] for relatively short-term storage," Casady advised. "The last point or so of moisture can be removed as grain is cooled."

Storage time for corn (days)

	Grain moisture %
Temperature	15	16	18	20	22	24	26
35 degrees F	n/a	670	265	112	74	49	37
45 degrees F	650	385	150	64	42	28	21
55 degrees F	360	215	86	36	24	16	12
60 degrees F	270	165	65	28	18	12	9
65 degrees F	200	125	49	21	14	9	7
70 degrees F	152	93	37	16	10	7	5

Storage moisture %

	Through winter	Up to one year	Long term
Corn	15.5	14	13
Grain sorghum	15.5	14	13
Soybeans	14	12	11
Small grains	14	13	13
Sunflowers	10	8	8

But don't just cool it and forget it. Inspect stored grain weekly to catch a minor problem before it gets out of hand.

"To reduce the risk of spoilage, grain should be dried an additional percentage point below market moisture contents for safe storage into next spring," said Casady. "And dry by 2 percentage points if you're holding grain through summer."

Keep in mind grain dried below market-dictated moisture content will "shrink" somewhat. If the market moisture of corn is 15 percent, you're selling more than eight pounds of water with each bushel. With corn at $1.50 per bushel, that water is worth 2.5 cents per pound. If grain must be over-dried by 1 percentage point to reduce the risk of spoilage, you lose the opportunity to sell about two-thirds of a pound of water.