What is the primary source of phosphorus in ecosystems?

The primary source of phosphorus in ecosystems is the weathering of rocks. Throughout this process, phosphate minerals within the rocks are broken down and released into the soil and water. This natural weathering is crucial because it provides the essential phosphorus that plants and microorganisms need for growth and development.

Phosphorus is not abundant in the atmosphere, unlike nitrogen, and does not have a significant gaseous phase; therefore, atmospheric deposition does not play a major role in its availability. While runoff from agricultural lands can add phosphorus to water bodies, it is generally a secondary source resulting from soil and sediment erosion, not a direct supply. Organic matter decomposition contributes to the recycling of phosphorus already present in the ecosystem but does not act as a primary source; it's primarily about redistributing existing phosphorus rather than introducing new supplies through mineral weathering.