Weather whiplash, a phenomenon in which extreme seesawing between drought and flood occurs, is now driving deterioration of water quality and forcing municipalities to seek expensive solutions so their residents can have clean and safe drinking water. Modern agriculture is inextricably tied to declining surface water quality, with associated national and global ecological and economic problems.
Agriculture is a major source of reactive nitrogen and interacts with hydrology to control nitrogen loading to aquatic ecosystems. Future hydrological changes that are associated with climate will alter nitrogen loading to freshwater ecosystems in ways that are just beginning to emerge.
That’s according to research which indicates that U.S. Midwest agricultural regions will experience more drought and periods of excessive rainfall, and these will be “really big storms,” according to Terry Loecke, the study’s lead author and an assistant professor of environmental studies at the University of Kansas. He and his team of researchers have created a weather whiplash index, which is calculated as the total precipitation from January to June of each year (1951–2099) minus the total precipitation from July to December of the previous year (1950–2098), divided by the total precipitation over that entire period.
And they’ve found that extreme weather events change the storage of nutrients in the agricultural landscape, especially nitrogen used in fertilizing farms.
“Farmers put on their normal amount of fertilizer, but when we have a drought, plants don’t grow as big and don’t take up as much nitrogen,” Loecke said. “Instead of going into the plants, which would be harvested, it stays in the soil — and no water is flushing it away.” Floods carry the nitrogen into rivers, which often supply local communities with drinking water.
With climate change predicted to increase the frequency and severity of growing-season drought and produce more extreme precipitation in the spring, agricultural crop yield will be reduced but soil nitrate concentrations will be enriched.
And who will pay for the nitrogen remediation? You guessed it: the taxpayer. Water departments are finding themselves forced to build new facilities to eliminate nitrogen from municipal water supplies.