Less lawn care boosts soil biodiversity, study finds
Turfgrass—including sports fields, roadside ditches and residential lawns—makes up 40 million acres of the United States' land surface, bigger than the entire state of New York. Collectively, all that grass plays a critical role in ecological processes such as absorbing and filtering water, sequestering carbon and providing habitat for an array of creatures.
A new study from Cornell AgriTech, in the February issue of Urban Forestry & Urban Greening, demonstrates that less-intense management of turfgrass results in greater abundance, richness and diversity of soil-dwelling organisms.
Previous research has demonstrated a link between lower-intensity management and benefits for above-ground species, including pollinators, but much less research has explored how differing management strategies impact soil organisms.
Limiting pesticide application on grasses especially benefits a group of mites, Mesostigmata, which are natural predators of agricultural pests like nematodes and spider mites, the researchers found.
"There's this famous story about eliminating the wolves from Yellowstone, and it caused widespread negative impacts to the rest of the food chain. Having these intact food webs is important underground, as well," said first author Hayden Bock, Ph.D. '24, formerly a student in the lab of Kyle Wickings, associate professor of entomology in the College of Agriculture and Life Sciences (CALS) and now a postdoctoral researcher at Penn State University.
"Mesostigma feed on a wide variety of other organisms and act as a top-down control in the food web. Having them there in the right quantities is important to the health of the entire food web."
The study, carried out at Cornell AgriTech's Geneva, New York, campus, involved separating the campus lawn into three management categories:
- High-intensity management, similar to "calendar" plans suggested by big-box stores. This included four applications of herbicide, insecticide and fertilizer products throughout the growing season, in addition to mowing.
- A mid-intensity treatment suggested as best practice by most integrated pest management experts. This included mowing plus two fertilizer applications, and only applying insecticide/herbicide if needed based on "scouting" turfgrass for problem species. In the experimental plot, this resulted in a significant decrease in pesticide use.
- A low-intensity treatment, with no application of fertilizer, herbicide or insecticide, and only weekly mowing.
Bock took five soil samples from each plot over the course of the two-year experiment and assessed each for abundance and diversity of soil-dwelling creatures, soil physical and chemical properties, microbial abundance and biomass, soil water content and plant communities.
"Within that full boundary—the size of an American football field—we found 87 different types of soil organisms," Bock said. "It's hard to find 87 species of animals, or even insects, above ground in such a small area, but below ground, there's a wealth of biodiversity that people may not be aware of. Turfgrasses can be a hotspot for biodiversity, even in highly urbanized landscapes."
Low-intensity management resulted in "substantial decreases in lawn quality" as measured by the National Turfgrass Evaluation Protocol, which includes characteristics like turf greenness, mow quality, amount of dead turf, and presence of weed species and other plant types. There was no substantial difference among management types in soil carbon and nitrogen levels, or on decomposition of organic matter.
"To me, one of the most important outcomes of this work is that it highlights the tradeoffs that come from reducing management inputs," said Wickings, a co-author of the study. "While less intensively managed lawns may not deliver the same level of aesthetic quality, they give a return on biodiversity."
"Lawns provide cultural services, like aesthetics and recreation, and we want to protect those uses while also maximizing the environmental benefits lawns can provide if they're managed in a mindful way," Bock said. "Homeowners should have a clear sense of their goal for their lawns and then choose management strategies that will maximize their efforts."
More information: Hayden W. Bock et al, Lawn management intensity leads to contrasting effects on belowground ecology and turfgrass aesthetic, Urban Forestry & Urban Greening (2024).
Provided by Cornell University
