CLEVELAND -- Changes in agricultural practices on farms around the Lake Erie basin have reduced the amount of pollutants in runoff into rivers that feed the lake, according to a landmark study by Case Western Reserve University geologists.
Examining the water quality of the Maumee and Sandusky rivers, Peter Whiting, CWRU associate professor of geological sciences, and Doug Moog, CWRU senior research associate, found that cropland remains the biggest contributor to sediment and pollution that flow into Lake Erie. They reported their findings in the Journal of Environmental Quality.
The geologists examined the water quality of the rivers for the amounts of sediment, phosphorus and nitrogen that were linked to changes in water runoff, climate and agricultural practices. Once they accounted for the amount of runoff, they then considered changes in agricultural practices and climate.
Winter temperatures rose in the Lake Erie Basin during 1976-95, as they have globally. Snowfall and snow cover have decreased by 40 percent, and winter temperatures increased by 4¢ªF per decade. These climate changes resulted in more runoff from exposed land surfaces during the winter months, and the runoff doubled the amount of sediment and nitrogen flowing into the lake during winter months. In addition, nitrogen levels have increased by as much as 500 percent, because water soaked into bare ground and leached nitrogen from the soil during the winter months, according to the researchers.
During other times of the year, Whiting and Moog noted that changes in agricultural practices resulted in improved water conditions. They found phosphorus levels from fertilizers decreased by more than 50 percent for all seasons and linked the decrease to the amount of land left fallow or in conservation tillage of planting without plowing or with little mulching.
¡°As more land has been left fallow and farmers have adopted more environmentally friendly practices, the amount of phosphorus in the river water has dropped and less has reached Lake Erie through these rivers,¡± the researchers reported.
Materials provided by Case Western Reserve University. Note: Content may be edited for style and length.
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