The most common form of entry of the phosphorus is by human use of the fertilizers which is released into the groundwater.
Most of the fertilizers being used in agriculture contains nitrogen and phosphorus which is carried to the aquatic ecosystem through surface runoff. When the tropical rainforest are cut down by humans and fertilizers are being used in large amounts the nutrients stored in plants or rocks are washed by the heavy rains and they reach groundwater or other water bodies. Therefore, the humans alter the natural phosphorus cycle majorly in several mentioned ways.
