OOS 29-3 - Residential yard management practices control soil carbon and nitrogen in six US cities

Friday, August 16, 2019: 8:40 AM
M100, Kentucky International Convention Center
Carl Rosier1, Meghan Avolio2, Peter M. Groffman3, Susannah B. Lerman4, Christopher Neill5, Diane Pataki6 and Tara L.E. Trammell1, (1)Plant and Soil Sciences, University of Delaware, Newark, DE, (2)Department of Earth & Planetary Sciences, Johns Hopkins University, Baltimore, MD, (3)Cary Institute of Ecosystem Studies, Millbrook, NY, (4)Northern Research Station, USDA Forest Service, Amherst, MA, (5)Woodwell Climate Research Center, Falmouth, MA, (6)School of Biological Sciences, University of Utah, Salt Lake City, UT
Background/Question/Methods

Residential yards represent highly managed ecosystems that receive increased fertilizer and irrigation, which alters soil C and N cycling compared to non-managed native ecosystems. Sustainable management practices may lessen the effects of yard management on soil C and N cycling in residential yards. The overarching objective of our study is to identify how different yard management practices alter soil C and N cycling across six U.S. cities (Baltimore, Boston, Los Angeles, Miami, Minneapolis-St. Paul, Phoenix). We measured soil C, N, δ13C, and δ15N in yards with high and low intensity lawn management, yards designated as wildlife certified and water conserving (e.g., rain garden, xeriscape), interstitial parks, and reference sites. We hypothesize that yards managed for wildlife and water conservation will have similar soil C, N, δ13C, and δ15N to interstitial and reference sites since plant species (e.g., natives) and environmental conditions (e.g., moisture) are more similar. Furthermore, we expect high intensively managed yards will have greater soil C and N and enriched δ13C and δ15N relative to wildlife certified yards, water conserving yards, interstitial parks, and reference sites due to greater fertilizer and irrigation inputs stimulating plant productivity, C and N cycling rates, and associated 12C and 14N losses.

Results/Conclusions

We report preliminary results from Baltimore and Phoenix. Contrary to our expectations, we found no difference in soil δ13C across yards, interstitial parks, or reference sites in both cities, and no difference in soil C in Baltimore (p > 0.10). In Phoenix, we found greater soil C in yards with low and high intensity management compared to wildlife certified or water conservation yards, interstitial parks, and reference sites (p < 0.01). Soil N and δ15N results support our predictions that intensively managed yards have more soil N and δ15N than interstitial or reference sites. In Phoenix, soil N and δ15N was significantly greater in low and high intensity management than wildlife certified yards, interstitial parks, and reference sites (p < 0.05). Baltimore followed the same trend with greater soil δ15N in low and high intensively managed yards than interstitial or reference sites (p < 0.05). These results suggest that yards managed as lawns have greater soil N pools and N cycling rates with associated 14N losses, and support the importance of yard management practices on soil N cycling. Complete analysis of all six cities will further inform how yard management practices drive soil C and N cycling across differing climates.