Though phosphorus is necessary, too much of a good thing can be bad. Excess phosphate derived from fertilizers, detergents and other human sources makes its way into lakes and coastal waters by runoff, leaching or erosion, causing massive algae blooms that can affect taste and clarity of drinking water. Moreover, when algae die, thick pads sink to the bottom and oxidize, reducing dissolved oxygen and creating an environment inhospitable to fish. Too little phosphorus also is a problem. Crop harvesting can deplete phosphorus from agricultural lands, and old, weathered soils hold onto phosphate tightly, reducing its availability to plants.
Most phosphate fertilizer is derived from rock phosphate - a nonrenewable resource.
Cade-Menun studies phosphorus cycling in temperate forests including warm, dry woods of the Sierra Nevada and cool, wet rainforests of the Pacific Northwest. She also is collaborating with Paytan to adapt techniques for soils to ocean sediment trap samples to track which compounds degrade first, releasing their phosphorus back into the water and making it available to organisms. I think it would be exciting to link the phosphorus forms revealed by NMR spectroscopy back to the soil organisms producing them, and to link specific enzyme production to the transformation of these phosphorus forms. In this high-rainfall environment, where natural forest fires rarely occur, the phosphorus became occluded and unavailable to replanted trees, leading to phosphorus deficiencies despite high soil total phosphorus concentrations. But in drier ecosystems, such as the Sierra Nevada where fire regularly occurs, it may be an important means by which phosphorus is released back to plant-available forms.