<p> The Phosphorous Cycle</p><p>Source: http://vincejtremante.tripod.com/cycles/phosphours.htm</p><p>- The combination of three factors makes phosphorus a nutrient of concern in most ecosystems:  Most soils have only small amounts from the weathering of unevenly distributed rocks.  Phosphorus is more insoluble than other nutrients and less mobile, hence less phosphorus travels in the soil solution; roots generally must grow into a zone of phosphorus availability.  Phosphorus that drains from the land to the ocean is used by organisms in the surface waters, but a considerable amount is lost to the sediments in the shells and bones of marine organisms and by precipitation and settling of phosphates.</p><p>ES – Biogeochemical Cycles (Handout) SCI44E pg. 1</p>