The rise of conservation tillage, in which farmers leave the remnants of plants that have been harvested in the fields until they are ready to plant new crops, has helped to reduce erosion and soil loss. However, it might also be contributing to an increase of phosphorus in Lake Erie and presumably other bodies of water as well. This increase is mostly in the form of soluble phosphorous, which is being used more often in agricultural fertilizers. Unfortunately, it is also getting into rivers, streams, and lakes, where it is leading to dangerous algal blooms.
The algae feed off the phosphorus, and since there’s so much more of it, an overabundance of algae blooms. These are dangerous to fish and other animals, as well as plants, in those bodies of water. In 2014, an algae bloom in Lake Erie resulted in 400,000 people in Toledo, Ohio being unable to drink their city tap water.
In 2016, the American and Canadian governments took steps to start reducing phosphorous levels in Lake Erie by 40 percent, which should help, but more research is needed to discover the best ways to do this.
“Effective conservation is an adaptive process,” said study co-author Professor Andrew Sharpley of the University of Arkansas. “In the case of Lake Erie catchments, reduced land tillage dramatically reduced erosion, but without changing fertilizer management practices, this effectively trapped phosphorous at the soil surface.”
There is never one simple solution to the challenges of maintaining threatened or damaged ecosystems. That a solution has worked in some ways but failed in others does not mean that we should abandon it outright, but we do need to find ways to further adapt and improve our conservation efforts.
“The main lesson learned is that there can be unintended consequences of changing farm conservation practices, which should be recognized,” Sharpley said.
Ideally, further research into this problem will help us determine the best way to conserve soil and soil nutrients in agriculture, while also not leading to dangerous algal blooms in water ways.