Apatites are a major mineral source of this element, which occludes on older soils, making it most likely to limit (*) primary production on those soils.
Zebra mussels and other dreissenids are thought to cause a nearshore shunt of this element in lakes. Cluster roots secrete carboxylates in order to mobilize this element, and across ecosystems, diffusion is far more important than mass flow for this element's uptake due to its low soil mobility. In plant seeds and bran, this element is mainly stored as phytic acid. Apatites are a major mineral source of this element, which occludes on older soils, making it most likely to limit (*) primary production on those soils. This element is the second designated by the three-number fertilizer code. Much of this element's inputs on islands comes from guano, which was mined as a source of this element. For 10 points, name this primary element found in an ion which, along with sugar, forms the backbone of DNA.
Zebra mussels and other dreissenids are thought to cause a nearshore shunt of this element in lakes.
phosphorus [prompt on "phosphate"]