An immobile soil nutrient Phosphorus is one of the macronutrients essential for plant growth. Sometimes phosphorus in lawn and garden fertilizers is implicated as the source of pollution, but this is not an accurate assessment of the problem. Although misuse or misapplication may pollute lakes, proper application poses no threat of lake pollution and may reduce pollution possibility. The major sources of phosphorus in runoff are from lawn clippings and tree leaves left in the streets and gutters. Other sources of phosphorus may come from soil particles either blown into the lakes by wind erosion or carried in runoff over bare soil.
Inorganic phosphorus moves very little in soil.
When applied and incorporated as a fertilizer, phosphorus is quickly bound by soil particles. Phosphorus taken up by plants is incorporated into organic compounds. If not mixed into the soil, organic phosphorus from plant residues such as lawn clippings and tree leaves is soluble and a potential pollution source. However, when gutters were swept weekly and kept free of plant residue, the phosphorus level was 30 to 40 percent less than in areas where no sweeping occurred. This indicates that plant residues such as lawn clippings and leaves have considerable potential for pollution of lakes whether or not they were growing in fertilized soil.