UNIVERSITY PARK, Pa. -- Nothing says "country" like a stately barn flanked by a majestic silo. That visual image may slowly become a thing of the past, as more farmers opt for different types of storage silos, says an agricultural engineer in Penn State's College of Agricultural Sciences.

"Every farm is different, and every farmer has personal preferences for certain types of storage facilities, but nowadays many farms have stopped using tower silos in favor of other storage systems," says Dennis Buckmaster, associate professor of agricultural engineering.

In Pennsylvania, silos typically are used to store livestock forage to feed the animals over the entire year. The forage is usually corn silage or hay crop (grass or alfalfa) silage. Buckmaster says that as farms expand and herd sizes increase, many producers are opting to use different silage systems to lower costs or increase efficiency.

Buckmaster says each silo system has advantages.

--Top-unloading Tower Silo: Most of these silos are used in conjunction with a conveyor system to prepare and deliver mixed livestock feed. One person can operate the entire system, but it can be time-consuming for large herds (200 cows or more).

--Bottom-unloading Tower Silo: Unloading and feeding is automated as well. Bottom unloading silos have the least amount of storage loss of any silo, but they also are the most expensive silo to build, according to Buckmaster. "Tower silos take up less space, but that is probably oversold as an advantage," Buckmaster explains.

--Bunker Silo: Also called horizontal silos, these typically are constructed as 8- to 20-foot trenches surrounded on three sides with earthen or concrete walls. The stored feed is covered by plastic. "A bunker silo is low cost and can be filled rapidly and fed out rapidly," Buckmaster says. "This is more efficient for farms that have a large herd and use drive-through barns to feed."

--Stack or Pile: This is nothing more than piling feed on a concrete slab and covering it with plastic. Piling feed is more a short-term option.

--Silo Bags: These long, heavy plastic tubes resemble immense sausages and can be stored wherever the farmer wants to put them. They have low storage loss, if farmers manage the feed properly and make sure the bags do not develop holes.

--Plastic-wrapped Round Bales: These individual storage bales, which look like giant marshmallows, can be very efficient for smaller operations. "The same equipment is used to make both the individual round bales for silage, and for harvesting the forage crop as dry hay," Buckmaster explains. "There's no need to invest in equipment to operate or unload other silo types."

Buckmaster says bunker silos -- with low cost of construction and faster feeding for large numbers of animals -- are the most popular choice for most farmers these days. "There aren't as many safety issues with bunker silos," Buckmaster says. "There is little threat from gases or dust, and if it catches on fire there is no structure to collapse."

Buckmaster says people with nostalgia for old barns and silos needn't worry about losing their bucolic rural views -- yet. "For now, you'll still see tall silos, but many of the older, smaller silos less than 60 feet tall may be empty," he says. "Most will remain standing for years to come. Silos have a very long life -- the three tower silos on my family's farm have been up for more than 30 years, and they're still going strong."

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EDITORS: For more information, contact Dennis Buckmaster at 814-865-3392.

Contacts: John Wall jtw3@psu.edu 814-863-2719 814-865-1068 fax