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Degree

Doctor of Philosophy, Ohio State University, Environmental Science, 2011.

Abstract

In an attempt to slow the increase in atmospheric CO2 enrichment, researchers are looking at the capacity of world soils to sequester carbon (C) and mitigate global climate change (GCC). Analyses of U.S. turfgrass soils throughout diverse ecoregions indicated that home lawns sequester soil organic carbon (SOC). Rates of SOC sequestration to 15 cm depth ranged from 0.01% yr-1 to 0.70% yr-1 with the majority of lawns sequestering SOC to concentrations of 2-3%. Notably high SOC concentrations were observed in Minneapolis, MN (5.6%), Wooster, OH (3.4%), Denver, CO (3.2%), and Duluth, MN (3.1). In contrast, notably low concentrations were observed for soils located in Atlanta, GA (1.5%). Differences in SOC concentration and pool were attributed to differences in climatic and soil properties across ecoregions. The mean annual temperature (MAT) was negatively correlated with SOC concentration and pool, while both mean annual precipitation (MAP) and soil bulk density (ρb) indicated a nonlinear interaction with optimal SOC concentrations at MAP of 60-70 cm yr-1 and ρb of 1.4-1.5 Mg m-3. Additionally, soil nitrogen (N) concentration was positively correlated with both SOC concentration and pool. Rates of SOC sequestration ranged from 0.9 Mg C ha-1 yr-1 to 5.4 Mg C ha-1 yr-1, with a national average of 2.8 ± 0.3 Mg C ha-1 yr-1. Differences in rates of SOC sequestration were also attributed to differences in MAP, soil N concentrations, and ρb, however, SOC sequestration rate was also positively correlated with fine soil texture content and pH. The potential C sink capacity of soils was determined and ranged from 20.8 ± 1.0 Mg C ha-1 in Portland, ME to 96.3 ± 6.0 Mg C ha-1 in Minneapolis, MN, with an average across ecoregions of 45.8 ± 3.5 Mg C ha-1. The hidden carbon costs (HCC) of home lawn maintenance due to fertilizer use (0.06 Mg Ce ha-1 yr-1) and mowing fuel combustion (0.19 Mg Ce ha-1 yr-1) produced a mean total emission across sites of 0.25 Mg Ce ha-1 yr-1. Accounting for both the SOC sink capacity and HCC, SOC sequestered through home lawn establishment is negated by fertilizer and mowing emissions by 170-198 years post lawn establishment. Mean potential SOC sink capacity for all home lawns in the State of Ohio and the U.S. was estimated at 17.8 and 496.3 Tg C, respectively. Additionally, the HCC due to fertilizer application and mowing under low and high management regimes for all U.S. lawns was estimated at 2504.1 Gg Ce yr-1and 7551.4 Gg Ce yr-1, respectively. This creates a C-positive system for 71-223 years for Ohio's home lawns and 66-199 years in the U.S.. In order to maximize the potential of home lawn turfgrasses to sequester SOC, lawns should be established and managed where MAT is low, MAP is moderate, soil N concentrations are high, fine texture concentrations are maximized, pH is low, and ρb is optimal. Additionally, the HCC due to maintenance emissions should be minimized to increase the SOC sink capacity of home lawns and improve their benefits to GCC mitigation.

Subject Headings

Agriculture; Atmospheric Sciences; Biology; Botany; Climate Change; Ecology; Environmental Education; Environmental Management; Environmental Science; Environmental Studies; Gases; Landscaping; Land Use Planning; Plant Biology; Plant Sciences; Sociology; Soil Sciences; Ur

Keywords

Soil organic carbon; Carbon sequestration; Urban soils; Turfgrass soils; Global climate change; Soil properties; Climate; Hidden carbon costs; Soil bulk density; Soil texture; Soil pH; Precipitation; Temperature; Soil nitrogen

Committee / Advisors

Rattan Lal (Advisor)
Elena Irwin (Committee Member)
Karl Danneberger (Committee Member)
Richard Moore (Committee Member)

Pages

353p.

Document number: osu1306499049
Permalink: http://rave.ohiolink.edu/etdc/view?acc_num=osu1306499049

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