Abstract

For many years, environmental agencies have sought to improve the water quality of lakes and estuaries by reducing inputs of phosphorus. New research indicates that we must reduce both phosphorus and nitrogen to reverse eutrophica-tion symptoms. Nutrients are chemical elements that influence the productivity of all ecosystems. Nitrogen and phosphorus are two nutrients that are essential for the growth and survival of plants and animals, but often are present in short supply. Both nitrogen and phosphorus are applied regularly through fertilizer to increase the yield of crops needed to feed human populations. Fertilizers also are used widely for residential and commercial landscaping purposes.