The Effects of Fertilizer Sources on the Mitigation of Greenhouse Gas Emissions from Creeping Bentgrass Greens and Kentucky Bluegrass Roughs.

The purpose of this project was to determine the impact cultural management strategies have on greenhouse gas emissions which are known to contribute to global climate change. A two year field study evaluating fertilizer source (Urea, Encapsulated Polyon, and Milorganite), turfgrass species (Agrostis stolonifera and Poa pratensis), and site location (soil moisture regime) on greenhouse gas (carbon dioxide [CO2], methane [CH4], and nitrous oxide [N2O]) emissions. Samplings occurred weekly throughout the summer and fall of 2013-2014. Gas samples were taken using a vented closed gas chamber for 40 minutes following the USDA-ARS GRACEnet methods. Soil temperature, soil moisture, canopy greenness, and turfgrass quality were also collected. Site location was significant (p<.0001) for canopy greenness in 2013-2014 except for two dates in September 2013 following fertilization. Canopy greenness was significantly higher for Milorganite on roughs and higher for Urea on greens. Turfgrass quality was significantly higher for Polyon and Urea on greens and Milorganite and Urea on roughs. Results from 2013 indicate higher CO2 emissions (p<0.1) on the green than on the roughs, while in 2014 the dry rough had significantly (p<0.05) higher emissions than the green. Methane (CH4) emissions were significantly (p<0.05) higher in the control than for Polyon across sites in 2013. In 2014, Milorganite had significantly higher methane emissions than Polyon and Urea on two sampling dates. In both years, site location showed significant (p<0.001) influence on N2O emissions; treatment effects were not significant. The dry rough showed significantly higher N2O emissions than the other two sites. Soil temperature and soil moisture were significant predictors of CO2 and N2O emissions in 2013, with only CO2 showing significant trends in 2014. Future research should focus on identifying water conservation practices that will decrease greenhouse gas emissions while maintaining adequate soil moisture needed for plant health and turfgrass quality.