Many general purpose fertilizers contain the elements nitrogen, phosphorus, and potassium. Phosphorus helps sustain plants by nourishing their roots and flowers. Though many fertilizers contain phosphorus, most lawns do not actually require the addition of it. It is often applied in excess because phosphorus moves very slowly down through the soil horizons. Surplus phosphorus washed off by storm runoff leads to algal blooms in aquatic systems like rivers, streams, lakes and ponds.
According to Section 65A of the Massachusetts General Laws, “No person shall purchase and apply or authorize any person, by way of service contact or other arrangement, to apply in the commonwealth any phosphorus containing fertilizer on lawn or non-agricultural turf.” There are exceptions however if:
- A soil test indicates it is needed. These can be purchased at local garden centers or soils can be sent off to local universities for testing. Soil tests should be completed every 3 or 4 years.
- Phosphorus can be used when establishing a new lawn
This law is designed to limit the amount of phosphorus entering the environment from non-point sources. According to the EPA, restricting phosphoric fertilizers can save up to $180 million in water treatment costs and reduce the amount of phosphorus entering streams and lakes by as much as 65 percent. This law was passed in August 2014 and is effective now, so there are alternative, phosphorus-free fertilizers for your lawn!
Some other tips to reduce risk of pollution from fertilizers include: use lime to maintain an adequate soil pH (see soil test for current pH); apply fertilizers when lawn in moderately moist; don’t apply fertilizers right before a heavy rainfall event; and aerating soils so they are less compacted and allow water to infiltrate.