With 55,000 tons of storage capacity in one stack yard and 30,000 tons in another, the managers at Agrex, Inc., want to make sure that none of their hay overheats. So they have a temperature detection cable installed in the middle of every stack.
Temperatures are monitored with a hand-held instrument that connects to the end of each cable. Readings are taken weekly during the first four to six weeks of storage, and monthly thereafter.
Larry Jackson, vice president of operations and risk management, says temperature monitoring helps prevent fires and safeguards hay quality.
“We know that there is no questionable quality when we're removing the stacks,” says Jackson. “We have first-hand knowledge that the hay hasn't heated during storage.”
He says it's not unusual for hay's temperature to hit 130° during the first two or three weeks. Air circulation usually will lower it. But if it continues to rise after monitoring and gets to 140°, stacks are taken apart to improve air movement around troublesome bales.
“We've done that a couple of times,” he says.
Agrex is a major domestic and export marketer of grain, hay and other feed products. It buys baled hay from growers and transports it to stack yards at Moses Lake, WA, and Stafford, KS. Stacks at the two locations range in size from 100 to 300 tons, so the company has many temperature detection cables.
It buys them from two suppliers: Tri-States Grain Conditioning (TSGC), Spirit Lake, IA, and Boone Cable Works and Electronics, Boone, IA. Both deal primarily in grain bin monitoring equipment, adding haystack cables a few years ago.
So far, Agrex is the only client. But Jackson believes growers who store hay in outdoor stacks or sheds could benefit, too.
In addition to reducing worry, temperature monitoring makes hay more insurable. Insurance companies are more willing to provide coverage if they know temperatures will be monitored, and sometimes offer lower premiums or at least lower deductibles.
“Our insurance premiums overall have been reduced by about 10% due to the fact that we monitor our haystacks,” Jackson reports.
He says the cables are easy to install as stacks are built with a telehandler. But growers may have to devise different installation strategies, depending on their hay handling methods. Cables might have to be installed vertically in some situations.
At Agrex, cables are pulled out just prior to stack removal. Each one has a hook for that purpose. They can be reused any number of times.
Thermocouples are situated every 14-16' along the cables, and each one reads temperatures in a 20' radius. So one cable is sufficient for most stacks.
Cable lengths vary from 100 to 300' and cost roughly from $100 to $500, depending on length. The least-expensive temperature-reading instruments cost about $300. They give separate readings for each thermocouple, but the figures must be recorded manually. Units that store temperatures for downloading onto a computer cost up to $600.