Carbon Dioxide Flux Under Warm Season Turfgrass.

Industrialization and urbanization have altered atmospheric composition, and increased greenhouse gas concentrations have caused global climate change. Greenhouse gases include carbon dioxide (CO₂) and other gases. Atmospheric CO₂ concentration has increased by ≈ 40 %, from 280 ppmv in 1850 to 391 ppmv in 2012. This increase, and the probability of increasing global temperatures, is expected to alter the distribution of carbon (C) between the atmosphere, vegetation and soils. Despite its large-scale presence in the urban ecosystem, the role of turfgrass in C cycling has received limited attention, and studies in warm-season turfgrasses are lacking.  The objective of this study was to estimate CO₂ flux from soil as affected by nitrogen (N) applied to bermudagrass (Cynodon dactylon x C. transvaalensis). The study was initiated in March, 2012 on seven-year-old ‘Tifway’ hybrid bermudagrass plots located at the Auburn University Turfgrass Research Unit (32.58° N, 85.50° W) on a Marvyn loamy sand (fine-loamy, kaolinitic, thermic Typic Kanhapludults) soil. The experimental design was a randomized complete block with four N rates of 24, 49, 98, and 196 kg N ha^-1 yr^-1 that were replicated three times. Carbon dioxide flux was measured weekly for 43 weeks using an automated soil CO₂ flux system (LiCor LI-8100A). Soil temperature and moisture were also determined during CO₂ flux measurements. Results showed strong correlation between CO₂ flux and N rate (r² = 0.91*). These results indicated that CO₂ flux during the study period increased from 92±2.0 to 123±3.0 Mg ha^-1 as N rate increased from 24 to 196 kg N ha^-1, respectively.