by Alicia Pimental
December 10, 2010
A new report by the Environmental Working Group finds that phosphorus – a nutrient that leads to algae blooms and low-oxygen “dead zones” in the Chesapeake Bay – is saturating the soil of farmland in many parts of the Bay watershed.
The report, Bay Out of Balance, finds that in 20 percent of the counties in the Bay watershed, more than half of the soil tested contained far more phosphorus than crops can use. Once soil is overloaded with phosphorus, the nutrient becomes a pollutant that can persist for many years.
Farmers apply phosphorus-rich manure and fertilizer to their land to help crops grow. Research in the report shows that fertilizer is being applied to soil that already has enough nutrients to meet plants’ needs. About 45 percent of the phosphorus that reaches the Bay comes from agriculture.
“One of most important things we can do to clean up Chesapeake Bay is ensure that farms add only the phosphorus that plants need to thrive,” said Rebecca Sutton, Ph.D., lead author of the report. We need to regard phosphorus as a potential pollutant, ensure that farmers don’t over-fertilize and find non-polluting ways to dispose of excess manure.”
The report lists three recommendations for the states to monitor and reduce the amount of phosphorus that is applied to the Bay watershed’s farmland:
- Implement uniform standards for phosphorus levels in soil to protect the health of local waterways
- Collect and assess data on phosphorus levels in soil
- Develop and implement a strict, science-based limit above which phosphorus should never be applied to fields
Visit the Environmental Working Group’s website to read the full report.