White keeps hay coolest, company study shows. Henry Ford used to say of his Model T that customers could have any color they wanted, as long as it was black.
For years, that was pretty much the case with hay tarps: black was basic. And dark-skinned covers protected hay from rain very well. But hay directly beneath black tarps was being "super-dried" to virtually zero moisture content.
"Until about 15 years ago, we used black hay tarps," says Glenn Knopp, president of Inland Tarp & Cover at Moses Lake, WA, a major manufacturer of hay covers.
"Then I noticed that the top bales in a tarp-covered stack were consistently lighter weight. We had a stack of 100-lb bales - stacked nine high - and bales in the top two layers weighed 15 lbs less when we loaded out, compared with when the bales went into the stack.
"Even if all the moisture was being dried out of the hay, bales shouldn't be losing that much weight," Knopp adds. "Something else was happening to the hay."
As Knopp studied the problem, he found that the heat was actually breaking down the chemical composition of the hay. Heat absorbed by black tarps and transmitted to the hay beneath was literally cooking the nutrients out of the forage.
"So we converted to a metallic-silver tarp, and that helped the situation considerably," he says. "But heat was still affecting hay quality."
Hay grower Bill Miller was noticing some differences, too.
"I didn't make any formal comparisons of different-colored tarps, but I have noticed that condensation is worse on the hay side of dark tarps," says Miller, of Sage, AR.
He speculates that the condensate is being drawn from the hay underneath.
Knopp made a side-by-side comparison of three tarps in California's Imperial Valley on a sunny day when the air temperature was 85. He placed thermometers under the tarps at the ends of bale stacks.
"Under the black tarp, the reading was 125," he says. "Under silver, the thermometer read 112. Under the white tarp, the temperature stayed within a degree or two of the outside air temperature."
That was more than three years ago. Shortly afterward, Inland Tarp & Cover began making hay tarps that are white on one side, silver on the other.
"We put a rain gutter on the white side, although the tarps are reversible," he says. "We encourage customers to use the white side up, but I think some producers still put silver on the outside because of habit."
Knopp notes that producers in areas with heavy snowfall also like to cover hay with the silver side up so snow will melt quicker.
"For another thing, when you're tarping a bale stack on a bright, sunny day, the white surface has a glare that is hard on the eyes," points out Miller, who admits he often turns the silver side up for that reason.
"My theory is, you don't want to add any more heat than absolutely necessary," Knopp says. "After you stack bales, they go through a heating process anyway, which can raise the temperature 10 or more. If you add another 10-20 to the stack by wrapping it in a dark-colored tarp, you're increasing the chance of a breakdown in the hay's nutrients."
In Knopp's opinion, that makes white the best color for hay covers, although silver is still the standard for the industry.
But, then, it took a number of years before the Model T came in colors other than black.
The seventh annual Mid-America Alfalfa Expo is set for Feb. 6-7 at the Adams County Fairgrounds, Hastings, NE.
Over 35,000 sq ft of indoor exhibit space will feature the latest in haying equipment, seed, irrigation systems, etc.
The speakers program will include presentations on sampling techniques and alfalfa's place in dairy rations, plus a panel discussion on the dairy industry's future.
Other highlights: An inventor's contest with cash prizes and an auction of exhibitor-consigned items. The expo is sponsored by the Nebraska Alfalfa Marketing Association. For info, contact Craig Buescher, Rt. 1, Box 54, Deweese, NE, 68934. Call (402-262-2311) or e-mail (firstname.lastname@example.org).