Observations of High Nitrate Concentrations in Forage Bermudagrass during Severe to Exceptional Drought Years

With the prediction of climate change-induced increases in drought frequency and severity in the southeastern USA, it is important to better understand the risks that drought may pose to NO3 accumulation in bermudagrass [Cynodon dactylon (L.) Pers.] forage. This report offers observations of NO3 concentration in Bermudagrass forage samples submitted to the University of Georgia’s Feed and Environmental Water Lab (FEWL) during the extreme to exceptional drought of 2007, the severe drought of 2008, and the four preceding seasons when drought stress was minimal or absent. The probability (P) of a sample being at high risk for nitrate toxicosis was the greatest for the extreme to exceptional drought of 2007 (P = 0.160), slightly lower in the severe drought year of 2008 (P = 0.105), and the lowest for samples from the 2003-2006 growing seasons (P = 0.082) when drought stress was minimal or absent.