Roadsides Benefit From Wastes, UF Researchers Say

August 18, 1997

GAINESVILLE–Roadside dumping may be the best way to keep state highways beautiful and safe, says a team of University of Florida researchers.

Litterbugs they aren’t, however. The waste they want to see spread alongside Florida highways is made up of organic material.

“The goal is to make roadsides a friendly environment to establish grass and at the same time get rid of waste products in an environmentally friendly way,” said turfgrass researcher Grady Miller, of UF’s Institute of Food and Agricultural Sciences.

Miller and his colleagues were charged by the Florida Department of Transportation with finding a way to improve roadside soil. The improved soil would help grass grow, and grass helps to stabilize roadways.

The researchers turned to cities and counties, which produce mountains of nutrient-rich organic wastes. Rather than use up precious landfill space with the wastes, the cities were glad to put the material at the disposal of the UF researchers. Miller said the material cannot be used on crops because it sometimes contains metals or glass.

“There’s no better location than roadsides,” Miller said. “They’re everywhere.”

In general, roadside soil is too sandy to hold nutrients or water, making it difficult for grass to grow well. Importing topsoil and adding commercial fertilizer helps but is prohibitively expensive. So the researchers turned to organic wastes.

“The roadside is a very harsh condition in which to grow turf,” Miller said. “The organic wastes add nutrients and hold water, making conditions more favorable for grass to grow.”

The compost has an added advantage over commercial fertilizer, said researcher Bob Black, in that it releases nitrogen slowly. With commercial fertilizer, there’s a quick flush of growth after the initial application but no sustained nourishment of the soil and grass.

Black said motorists cruising with their windows down might get a whiff of the compost after it’s dumped from trucks, but once it’s spread, the odor dissipates quickly and no one has complained.

In field studies along an interstate in Broward County and a four-lane in Hernando County, the researchers are studying how the organic material aids the establishment of new grass. Along two-lanes near Steinhatchee and Melrose, they’re using the compost as top dressing and looking at how it boosts the growth of the grass already there.

In UF’s state-of-the art Turfgrass Envirotron, where grasses from all over the world are monitored in three computer-controlled greenhouses, they are comparing the growth of roadside turf samples using both commercial fertilizer and the organic wastes. In all the samples, the grass nourished with organic wastes is faring better, Miller said.

“We’re seeing dramatic improvement in turf growth,” Miller said.

DOT landscape architect Gary Henry said roadside vegetation is necessary because it ensures the structural integrity of the roadbed by preventing soil erosion and keeping asphalt from crumbling. He said the news that roadside composting looks promising is welcome.

“Importing topsoil and adding fertilizer is very costly, so this alternative will be a big help,” Henry said. “This will save money, improve the grass and eliminate a landfill problem by reusing a material that still has some value.

“It’s a win-win-win situation,” Henry said.