Beginning September, 2013, Ahyayha began distributing phosphorus offset certificates to Supporters for the project One Oyster At A Time. Supporters may wonder how to calculate their personal phosphorus footprint in a manner similar to the calculator used for nitrogen. At this time, a similar calculator for phosphorus has yet to be developed, though Ahyayha and The Center for Natural Capital are working on the development of such a tool.
Until then, Ahyayha suggests the following:
To determine a person’s home and yard phosphorus footprint:
Step 1. Determine P from household activities (food, bathroom, etc.)
- If you are on a septic system, assume 5 lbs. per year comes from your system into the surrounding environment.
- If you are on public wastewater, assume 0 lbs. per year into the surrounding environment.
Step 2. Determine P from fertilizer
- If you use fertilizer, assume you use 10-10-10, thus 5 lbs. per 50 lb. bag.
Step 3. Add these two sources together
Step 4. Compare your footprint to Chesapeake Bay Clean Up Goal:
Using information from the EPA, Chesapeake Bay Program Office, and the George Washington Regional Commission, the phosphorus diet (goal) for folks that live in the Rappahannock River Watershed is ~ 1/3 lb. per person per year. This means that for the portion of excess nutrients that comes from people and their daily activities in their homes and yards, 1/3 of a pound of phosphorus per person per year is the maximum a highly functional Bay can handle. Note: this is a very rough estimate.