Maryland’s proposed, but controversial, Phosphorus Management Tool would help achieve significant nutrient reductions from the state’s agricultural lands if implemented, according to an analysis by the Bay Program.
The phosphorus tool, which was proposed by the state Department of Agriculture last year, uses information about phosphorus concentrations in soil and other site-specific conditions to determine the likelihood that the nutrient would run off fields and into waterways. Farmers could be prohibited from applying additional phosphorus to fields that score too high.
But the tool has been controversial because it could make large amounts of Eastern Shore cropland off-limits for additional applications of litter produced by Delmarva’s poultry farms.
Poultry litter typically contains a higher ratio of phosphorus to nitrogen than crops need. When farmers apply enough litter to meet the nitrogen needs of a crop, they typically overapply phosphorus.
That has resulted in many fields, particularly on the lower Eastern Shore, being saturated with phosphorus, leading to increased nutrient runoff. As a result, phosphorus concentrations have increased in some Eastern Shore rivers.
Use of the new phosphorus tool would mean that excess litter would need to be hauled farther to find suitable fields for application — or in some cases, be hauled out of the watershed altogether.
Meanwhile, farmers who were using litter for fertilizer would have to buy chemical fertilizer to meet the nitrogen demand of crops (the phosphorus needs could be met by the phosphorus already in the soil).
The administration of Maryland Gov. Martin O’Malley twice last year tried to implement the new phosphorus tool but withdrew it in the face of stiff opposition.
Still, the administration pledged to implement the rules before the end of this year. Implementation of the phosphorus management tool is a key part of the state’s watershed implementation plan to meet its Bay nutrient reduction goals.
The General Assembly, meanwhile, approved a budget amendment this year that would prohibit the state from finalizing the regulations until economists at Salisbury University completed an economic analysis of their impact.
The Bay Program analysis was prepared at the request of those economists.
The review examined the effectiveness of relocating 228,377 excess tons of chicken litter from five lower Eastern Shore counties toward meeting nutrient reduction goals.
As part of the Bay cleanup effort, the state needs to take all actions needed to meet nutrient reduction goals by 2025, and achieve 60 percent of those goals by 2017.
Using computer models, the EPA Bay Program Office calculated that:
- Trucking the litter out of the watershed would achieve Maryland’s 2017 nitrogen reduction goal for agriculture, and 97 percent of its phosphorus reduction goal for agriculture.
- Relocating the litter to areas within the state where it could still be applied to land would also achieve 2017 nitrogen goals, as well as 48 percent of the needed phosphorus reductions.
- Trucking the litter out of the watershed would achieve 17 percent of the 2025 agricultural nitrogen goal and 41 percent of the agricultural phosphorus reductions.
- Relocating the litter within the state would achieve 18 percent of the 2015 nitrogen goal and 20 percent of the phosphorus goal.
In a letter to the economists, Nick DiPasquale, director of the EPA Bay Program Office, said the calculations likely understate phosphorus reductions that would be achieved. If no additional phosphorus was applied to saturated soils, he said, crops would draw down the excess phosphorus over time, thereby reducing runoff.
“Implementing the [phosphorus management tool] is likely to yield additional reductions of excess nutrients beyond those described…as soil phosphorus levels slowly decrease in areas of historic overapplication of poultry litter, and as farmer transition to using inorganic nitrogen fertilizer and precision application of that fertilizer,” DiPasquale said.