GAINESVILLE, Fla. — Usually, when residents are urged to conserve water, they’re told to irrigate their lawns less. But Eban Bean and his University of Florida research colleagues want to use compost in new residential landscapes to see if it helps reduce the soil’s water needs.
Bean’s preliminary research into 30 years of weather data and soil properties from a model home site near Ocala, Florida, shows that incorporating compost should be able to save up to 25 percent in irrigation volume on lawns.
Bean, an assistant professor of agricultural and biological engineering at the UF Institute of Food and Agricultural Sciences, said soil in new developments is often from soil dug out to create stormwater ponds and gets compacted when homes are built. With compaction, you essentially squeeze or compress air out of soil, Bean said.
“As a result, it’s usually tough to try to establish a lawn, bushes and other aspects of a nice landscape,” he said. “Additionally, the lawn will likely hold very little water and will be hard for roots to penetrate.”
If roots can’t take hold in the soil, trees and shrubs don’t grow well because they can’t get the required water and nutrients. Furthermore, it can take decades for compaction and poor soil quality to improve, Bean said.
“Florida doesn’t have decades to improve its soil to the point that it uses water more efficiently,” Bean said. “More than 1,000 people are moving into the state each day. It’s difficult to build all the homes needed to accommodate the influx of new residents without putting soil in peril.”
Bean and his research colleagues are conducting an experiment at On Top of the World, an active adult community of 5,000 homes for people ages 55-plus near Ocala. As part of the study, participants apply 25 percent less irrigation on their lawns than their neighbors, Bean said.
Just before installing landscape plants, UF/IFAS researchers spread about a 1-inch layer of compost across the soil. They then till the compost, essentially kick-starting soil development by incorporating organic matter, nutrients and microbes, while loosening the soil, Bean said.
Every couple of weeks, Jovana Radovanovic, a graduate student majoring in agricultural and biological engineering through the UF/IFAS College of Agricultural and Life Sciences measures runoff and the soil’s ability to move water in and out. Radovanovic also collects samples for nutrient analysis.
In addition to the research at On Top of the World, Bean and his team are studying soil amending with composting at developments in Gainesville, Clermont and another in the Ocala area, but outside On Top of the World. They hope to expand their study areas to include Lakewood Ranch in Manatee and Sarasota counties in addition to a location in the Panhandle, most likely the Tallahassee area.
Bean and his team are almost halfway through this research project. When they finish, they’ll analyze the benefits and risks of amending with soil compost. Then, researchers will make recommendations for reducing irrigation.
Developers may find an incentive in the UF/IFAS soil recommendations because they might receive credit for stormwater runoff reduction in the future, while improving soils so they need less irrigation.
“Granted this depends on the overall results,” Bean said. “If incorporating compost can also be shown to reduce runoff and nutrients, it would be a greater incentive for builders to adopt the practice and protect Florida’s water resources.”
–Brad Buck, UF/IFAS