Runoff of Phosphorus and Nitrogen from Homeowner and Community Landscapes
By Joe Landaeta
Phosphorous is not an element that most Homeowners or landscape professionals would associate with water quality problems. Certainly, pesticides and nitrates easily come in mind when considering possible contamination of surface water. However, recognizing water quality problems and awareness that there are extremely high maintenance levels for lawns and landscaped areas within Harbor Bay Isle has led to concern about phosphorus and nitrogen levels leaching into our lagoon system.
Turfgrass grown mostly for visual, aesthetic and lounging on uses, is found in front and to the rear of many residences on the Island. Healthy, vigorous and attractive turfgrass is maintained by mowing, irrigating and fertilizing. Fertilizer that is applied excessively or inappropriately, can runoff or leach through the sandy soils on the island, and end up in the lagoon system where it may contribute to water pollution, algae and undesirable aquatic plant life.
Fertilizer replaces nutrients removed from the soil by growing plants. The amount of fertilizer applied should not exceed established levels, or turfgrass quality can decline.
Timing and methods of application should match the turfs’ needs and uptake abilities, taking into consideration soil and ambient temperatures, wind, rain and irrigation.
Soils on the island are coarse textured (sand), porous, and usually have low levels of organic matter like silt or clay. These are usually nutrient poor soils. However, the physical conditions are good for turfgrass growth when drainage is good and adequate supplemental nutrients are provided. Sandy soils that drain well are likely to leach certain nutrients such as nitrogen into the lagoon, when they are irrigated or when rainfall occurs.
Home maintenance tips for a cleaner lagoon system.
Make sure your gardener collects yard waste for composting and does not blow or rake leaves into the street or gutter. If you contract with a lawn maintenance service, limit fertilizer applications to twice a year (fall and spring), and limit application of actual nitrogen on cool season grasses to 4 pounds per 1,000 square feet. Chemical and other pesticides should not be necessary on lawn that is appropriately watered, mowed, thatched, and aerated. Never apply chemicals when rain fall is forecast
For additional information please contact the Director of Maintenance, Joe Landaeta, 510-865-3363 ext. 350.