Phosphorus management is best understood by balancing the close-up view against the big picture.

Some no-tillers can inject manure to help reduce phosphorus runoff and water quality degradation, which is the close-up part of the equation. But the shift in the structure of agriculture and land use, and its downstream impact on water quality that is not within the individual no-tillers control, represents the big picture.

The key is to balance both pictures when developing a phosphorus management strategy or nutrient management plan to reduce potential degradation problems in freshwater bodies of water. This is exactly what researchers have been trying to do in developing phosphorus management tools, according to Jennifer Weld, an Agricultural Research Service staffer located at Pennsylvania State University, and Joel Myers, state agronomist with Pennsylvania’s Natural Resources Conservation Service.

Working as a part of the National Phosphorus Research Project, Pennsylvania scientists have compared soil phosphorus with that found in water runoff. They have studied the economic and farm management implications of different phosphorus strategies compared to the traditional nitrogen-based nutrient management plan.

The Phosphorus Index

The phosphorus index takes into account various sources of phosphorus found in manure, fertilizer and soil phosphorus along with the transport processes for controlling phosphorus loss.

The primary phosphorus transport mechanisms are erosion and runoff, says Weld. There could also be some sub-surface drainage for no-tillers who have tile lines and leaching taking place in sandier soils.

She says areas having high sources of phosphorus and the potential to transport it…