The Phosphorus Cycle | Earth Science

<!DOCTYPE html> <html lang="en" dir="ltr"> <head>  <meta http-equiv="X-UA-Compatible" content="ie=edge"> <meta charset="utf-8"> <base href="https://www.visionlearning.com"> <title>The Phosphorus Cycle | Earth Science | Visionlearning</title> <link rel="canonical" href="https://www.visionlearning.com/en/library/earth-science/6/the-phosphorus-cycle/197"> <meta name="description" content="Learn about the phosphorus cycle through a discussion of the Experimental Lakes Area. Includes information on why phosphorus is important to all living things."> <meta name="keywords" content="phases of the phosphorus cycle, why is phosphorus important, do living things need phosphorus, eutrophication"> <meta name="viewport" content="width=device-width, initial-scale=1.0, shrink-to-fit=no"> <meta name="msvalidate.01" content="D8E20F39AD48052260032E56DE409970"> <script type="application/ld+json"> { "@context": "http://schema.org/", "@type": "Article", "mainEntityOfPage": { "@type": "WebPage", "@id": "https://visionlearning.com/en/library/earth-science/6/the-phosphorus-cycle/197" }, "name": "The Phosphorus Cycle", "headline": "The Phosphorus Cycle: Phosphates and fertilizer", "author": { "@type": "Person", "name": "Heather MacNeill Falconer, M.A./M.S." }, "datePublished": "2014-05-20 12:33:07", "dateModified": "2017-02-12T08:30:00+05:00", "image": { "@type": "ImageObject", "url": "/img/library/moduleImages/featured_image_197-23061209065649.jpeg", "width": 696, "height": 464 }, "publisher": { "@type": "Organization", "name": "Visionlearning, Inc.", "logo": { "@type": "ImageObject", "url": "http://visionlearning.com/images/logo.png", "width": 278, "height": 60 } }, "description": "All living organisms need phosphorous to survive and grow. This module describes forms that phosphorous takes in nature and how the element cycles through the natural world. A historical journey highlights how we came to understand this vital element. The Experimental Lakes Project shows the harmful effects of too much phosphorous on the environment as a result of human activities.", "keywords": "phases of the phosphorus cycle, why is phosphorus important, do living things need phosphorus, eutrophication", "inLanguage": { "@type": "Language", "name": "English", "alternateName": "en" }, "copyrightHolder": { "@type": "Organization", "name": "Visionlearning, Inc." }, "copyrightYear": "2014"} </script> <meta property="og:url" content="https://visionlearning.com/en/library/earth-science/6/the-phosphorus-cycle/197"> <meta property="og:title" content="The Phosphorus Cycle | Earth Science | Visionlearning" /> <meta property="og:type" content="website"> <meta property="og:site_name" content="Visionlearning"> <meta property="og:description" content="Learn about the phosphorus cycle through a discussion of the Experimental Lakes Area. 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href="/en/library/earth-science/6/factors-that-control-earths-temperature/234">Factors that Control Earth's Temperature</a></li> <li><a href="/en/library/earth-science/6/circulation-in-the-atmosphere/255">Circulation in the Atmosphere</a></li> </ul> </div> <button class="accordion__button" id="acc-button-hazards" data-accordion="button" aria-controls="acc-panel-hazards" aria-expanded="false"> <span class="accordion__button__label"> Hazards </span> </button> <div class="accordion__panel" id="acc-panel-hazards" data-accordion="panel" aria-labelledby="acc-button-hazards" role="region"> <ul class="nav text-color-link"> <li><a href="/en/library/earth-science/6/natural-hazards-and-risk/288">Natural Hazards and Risk</a></li> </ul> </div> <button class="accordion__button" id="acc-button-earth-history" data-accordion="button" aria-controls="acc-panel-earth-history" aria-expanded="false"> <span class="accordion__button__label"> Earth History </span> </button> <div class="accordion__panel" 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aria-controls="acc-panel-ecology" aria-expanded="false"> <span class="accordion__button__label"> Ecology </span> </button> <div class="accordion__panel" id="acc-panel-ecology" data-accordion="panel" aria-labelledby="acc-button-ecology" role="region"> <ul class="nav text-color-link"> <li><a href="/en/library/environmental-science/61/biodiversity-i/276">Biodiversity I</a></li> <li><a href="/en/library/environmental-science/61/biodiversity-ii/281">Biodiversity II</a></li> <li><a href="/en/library/environmental-science/61/ecosystem-services/279">Ecosystem Services</a></li> <li><a href="/en/library/environmental-science/61/population-biology/287">Population Biology</a></li> </ul> </div> <button class="accordion__button" id="acc-button-earth-cycles" data-accordion="button" aria-controls="acc-panel-earth-cycles" aria-expanded="false"> <span class="accordion__button__label"> Earth Cycles </span> </button> <div class="accordion__panel" id="acc-panel-earth-cycles" data-accordion="panel" aria-labelledby="acc-button-earth-cycles" role="region"> <ul class="nav text-color-link"> <li><a href="/en/library/environmental-science/61/the-nitrogen-cycle/98">The Nitrogen Cycle</a></li> <li><a href="/en/library/environmental-science/61/the-carbon-cycle/95">The Carbon Cycle</a></li> <li class="current">The Phosphorus Cycle</li> </ul> </div> <button class="accordion__button" id="acc-button-scientific-research" data-accordion="button" aria-controls="acc-panel-scientific-research" aria-expanded="false"> <span class="accordion__button__label"> Scientific Research </span> </button> <div class="accordion__panel" id="acc-panel-scientific-research" data-accordion="panel" aria-labelledby="acc-button-scientific-research" role="region"> <ul class="nav text-color-link"> <li><a href="/en/library/environmental-science/61/collaborative-research-in-the-arctic-towards-understanding-climate-change/183">Collaborative Research in the Arctic Towards Understanding Climate Change</a></li> <li><a href="/en/library/environmental-science/61/atmospheric-chemistry-research-that-changed-global-policy/211">Atmospheric Chemistry Research that Changed Global Policy</a></li> </ul> </div> </div> </div> <button class="accordion__button" id="acc-button-general-science" data-accordion="button" aria-controls="acc-panel-general-science" aria-expanded="false"> <span class="accordion__button__label"> General Science </span> </button> <div class="accordion__panel" id="acc-panel-general-science" data-accordion="panel" aria-labelledby="acc-button-general-science" role="region"> <div class="accordion accordion--secondary"> <button class="accordion__button" id="acc-button-methods" data-accordion="button" aria-controls="acc-panel-methods" aria-expanded="false"> <span class="accordion__button__label"> Methods </span> </button> <div class="accordion__panel" id="acc-panel-methods" data-accordion="panel" aria-labelledby="acc-button-methods" role="region"> <ul class="nav text-color-link"> <li><a href="/en/library/general-science/3/the-scientific-method/45">The Scientific Method</a></li> </ul> </div> <button class="accordion__button" id="acc-button-measurement" data-accordion="button" aria-controls="acc-panel-measurement" aria-expanded="false"> <span class="accordion__button__label"> Measurement </span> </button> <div class="accordion__panel" id="acc-panel-measurement" data-accordion="panel" aria-labelledby="acc-button-measurement" role="region"> <ul class="nav text-color-link"> <li><a href="/en/library/general-science/3/the-metric-system/47">The Metric System</a></li> </ul> </div> <button class="accordion__button" id="acc-button-physical-properties" data-accordion="button" aria-controls="acc-panel-physical-properties" aria-expanded="false"> <span class="accordion__button__label"> Physical Properties </span> </button> <div class="accordion__panel" id="acc-panel-physical-properties" data-accordion="panel" aria-labelledby="acc-button-physical-properties" role="region"> <ul class="nav text-color-link"> <li><a href="/en/library/general-science/3/temperature/48">Temperature</a></li> <li><a href="/en/library/general-science/3/density-and-buoyancy/37">Density and Buoyancy</a></li> </ul> </div> </div> </div> <button class="accordion__button" id="acc-button-math-in-science" data-accordion="button" aria-controls="acc-panel-math-in-science" aria-expanded="false"> <span class="accordion__button__label"> Math in Science </span> </button> <div class="accordion__panel" id="acc-panel-math-in-science" data-accordion="panel" aria-labelledby="acc-button-math-in-science" role="region"> <div class="accordion accordion--secondary"> <button class="accordion__button" id="acc-button-equations" data-accordion="button" aria-controls="acc-panel-equations" aria-expanded="false"> <span class="accordion__button__label"> Equations </span> </button> <div class="accordion__panel" id="acc-panel-equations" data-accordion="panel" aria-labelledby="acc-button-equations" role="region"> <ul class="nav text-color-link"> <li><a href="/en/library/math-in-science/62/unit-conversion/144">Unit Conversion</a></li> <li><a href="/en/library/math-in-science/62/linear-equations/194">Linear Equations</a></li> <li><a href="/en/library/math-in-science/62/exponential-equations-i/206">Exponential Equations I</a></li> <li><a href="/en/library/math-in-science/62/exponential-equations-ii/210">Exponential Equations II</a></li> <li><a href="/en/library/math-in-science/62/scientific-notation/250">Scientific Notation</a></li> <li><a href="/en/library/math-in-science/62/measurement/257">Measurement</a></li> </ul> </div> <button class="accordion__button" id="acc-button-statistics" data-accordion="button" aria-controls="acc-panel-statistics" aria-expanded="false"> <span class="accordion__button__label"> Statistics </span> </button> <div class="accordion__panel" id="acc-panel-statistics" data-accordion="panel" aria-labelledby="acc-button-statistics" role="region"> <ul class="nav text-color-link"> <li><a href="/en/library/math-in-science/62/introduction-to-descriptive-statistics/218">Introduction to Descriptive Statistics</a></li> <li><a href="/en/library/math-in-science/62/introduction-to-inferential-statistics/224">Introduction to Inferential Statistics</a></li> <li><a href="/en/library/math-in-science/62/statistical-techniques/239">Statistical Techniques</a></li> </ul> </div> <button class="accordion__button" id="acc-button-trigonometric-functions" data-accordion="button" aria-controls="acc-panel-trigonometric-functions" aria-expanded="false"> <span class="accordion__button__label"> Trigonometric Functions </span> </button> <div class="accordion__panel" id="acc-panel-trigonometric-functions" data-accordion="panel" aria-labelledby="acc-button-trigonometric-functions" role="region"> <ul class="nav text-color-link"> <li><a href="/en/library/math-in-science/62/wave-mathematics/131">Wave Mathematics</a></li> </ul> </div> </div> </div> <button class="accordion__button" id="acc-button-physics" data-accordion="button" aria-controls="acc-panel-physics" aria-expanded="false"> <span class="accordion__button__label"> Physics </span> </button> <div class="accordion__panel" id="acc-panel-physics" data-accordion="panel" aria-labelledby="acc-button-physics" role="region"> <div class="accordion accordion--secondary"> <button class="accordion__button" id="acc-button-light-and-optics" data-accordion="button" aria-controls="acc-panel-light-and-optics" aria-expanded="false"> <span class="accordion__button__label"> Light and Optics </span> </button> <div class="accordion__panel" id="acc-panel-light-and-optics" data-accordion="panel" aria-labelledby="acc-button-light-and-optics" role="region"> <ul class="nav text-color-link"> <li><a href="/en/library/physics/24/the-nature-of-light/132">The Nature of Light</a></li> <li><a href="/en/library/physics/24/electromagnetism-and-light/138">Electromagnetism and Light</a></li> </ul> </div> <button class="accordion__button" id="acc-button-mechanics" data-accordion="button" aria-controls="acc-panel-mechanics" aria-expanded="false"> <span class="accordion__button__label"> Mechanics </span> </button> <div class="accordion__panel" id="acc-panel-mechanics" data-accordion="panel" aria-labelledby="acc-button-mechanics" role="region"> <ul class="nav text-color-link"> <li><a href="/en/library/physics/24/defining-energy/199">Defining Energy</a></li> <li><a href="/en/library/physics/24/waves-and-wave-motion/102">Waves and Wave Motion</a></li> <li><a href="/en/library/physics/24/gravity/118">Gravity</a></li> <li><a href="/en/library/physics/24/thermodynamics-i/200">Thermodynamics I</a></li> </ul> </div> </div> </div> <button class="accordion__button" id="acc-button-process-of-science" data-accordion="button" aria-controls="acc-panel-process-of-science" aria-expanded="false"> <span class="accordion__button__label"> Process of Science </span> </button> <div class="accordion__panel" id="acc-panel-process-of-science" data-accordion="panel" aria-labelledby="acc-button-process-of-science" role="region"> <div class="accordion accordion--secondary"> <button class="accordion__button" id="acc-button-introduction" data-accordion="button" aria-controls="acc-panel-introduction" aria-expanded="false"> <span class="accordion__button__label"> Introduction </span> </button> <div class="accordion__panel" id="acc-panel-introduction" data-accordion="panel" aria-labelledby="acc-button-introduction" role="region"> <ul class="nav text-color-link"> <li><a href="/en/library/process-of-science/49/the-process-of-science/176">The Process of Science</a></li> </ul> </div> <button class="accordion__button" id="acc-button-the-culture-of-science" data-accordion="button" aria-controls="acc-panel-the-culture-of-science" aria-expanded="false"> <span class="accordion__button__label"> The Culture of Science </span> </button> <div class="accordion__panel" id="acc-panel-the-culture-of-science" data-accordion="panel" aria-labelledby="acc-button-the-culture-of-science" role="region"> <ul class="nav text-color-link"> <li><a href="/en/library/process-of-science/49/the-nature-of-scientific-knowledge/185">The Nature of Scientific Knowledge</a></li> <li><a href="/en/library/process-of-science/49/scientists-and-the-scientific-community/172">Scientists and the Scientific Community</a></li> <li><a href="/en/library/process-of-science/49/scientific-ethics/161">Scientific Ethics</a></li> <li><a href="/en/library/process-of-science/49/scientific-institutions-and-societies/162">Scientific Institutions and Societies</a></li> </ul> </div> <button class="accordion__button" id="acc-button-ideas-in-science" data-accordion="button" aria-controls="acc-panel-ideas-in-science" aria-expanded="false"> <span class="accordion__button__label"> Ideas in Science </span> </button> <div class="accordion__panel" id="acc-panel-ideas-in-science" data-accordion="panel" aria-labelledby="acc-button-ideas-in-science" role="region"> <ul class="nav text-color-link"> <li><a href="/en/library/process-of-science/49/theories-hypotheses-and-laws/177">Theories, Hypotheses, and Laws</a></li> <li><a href="/en/library/process-of-science/49/scientific-controversy/181">Scientific Controversy</a></li> <li><a href="/en/library/process-of-science/49/creativity-in-science/182">Creativity in Science</a></li> </ul> </div> <button class="accordion__button" id="acc-button-research-methods" data-accordion="button" aria-controls="acc-panel-research-methods" aria-expanded="false"> <span class="accordion__button__label"> Research Methods </span> </button> <div class="accordion__panel" id="acc-panel-research-methods" data-accordion="panel" aria-labelledby="acc-button-research-methods" role="region"> <ul class="nav text-color-link"> <li><a href="/en/library/process-of-science/49/the-practice-of-science/148">The Practice of Science</a></li> <li><a href="/en/library/process-of-science/49/experimentation-in-scientific-research/150">Experimentation in Scientific Research</a></li> <li><a href="/en/library/process-of-science/49/description-in-scientific-research/151">Description in Scientific Research</a></li> <li><a href="/en/library/process-of-science/49/comparison-in-scientific-research/152">Comparison in Scientific Research</a></li> <li><a href="/en/library/process-of-science/49/modeling-in-scientific-research/153">Modeling in Scientific Research</a></li> </ul> </div> <button class="accordion__button" id="acc-button-data" data-accordion="button" aria-controls="acc-panel-data" aria-expanded="false"> <span class="accordion__button__label"> Data </span> </button> <div class="accordion__panel" id="acc-panel-data" data-accordion="panel" aria-labelledby="acc-button-data" role="region"> <ul class="nav text-color-link"> <li><a href="/en/library/process-of-science/49/data-analysis-and-interpretation/154">Data Analysis and Interpretation</a></li> <li><a href="/en/library/process-of-science/49/uncertainty-error-and-confidence/157">Uncertainty, Error, and Confidence</a></li> <li><a href="/en/library/process-of-science/49/statistics-in-science/155">Statistics in Science</a></li> <li><a href="/en/library/process-of-science/49/using-graphs-and-visual-data-in-science/156">Using Graphs and Visual Data in Science</a></li> </ul> </div> <button class="accordion__button" id="acc-button-scientific-communication" data-accordion="button" aria-controls="acc-panel-scientific-communication" aria-expanded="false"> <span class="accordion__button__label"> Scientific Communication </span> </button> <div class="accordion__panel" id="acc-panel-scientific-communication" data-accordion="panel" aria-labelledby="acc-button-scientific-communication" role="region"> <ul class="nav text-color-link"> <li><a href="/en/library/process-of-science/49/understanding-scientific-journals-and-articles/158">Understanding Scientific Journals and Articles</a></li> <li><a href="/en/library/process-of-science/49/utilizing-the-scientific-literature/173">Utilizing the Scientific Literature</a></li> <li><a href="/en/library/process-of-science/49/peer-review-in-scientific-publishing/159">Peer Review in Scientific Publishing</a></li> <li><a href="/en/library/process-of-science/49/the-how-and-why-of-scientific-meetings/186">The How and Why of Scientific Meetings</a></li> </ul> </div> </div> </div> <button class="accordion__button" id="acc-button-scientists-and-research" data-accordion="button" aria-controls="acc-panel-scientists-and-research" aria-expanded="false"> <span class="accordion__button__label"> Scientists and Research </span> </button> <div class="accordion__panel" id="acc-panel-scientists-and-research" data-accordion="panel" aria-labelledby="acc-button-scientists-and-research" role="region"> <div class="accordion accordion--secondary"> <button class="accordion__button" id="acc-button-scientific-research" data-accordion="button" aria-controls="acc-panel-scientific-research" aria-expanded="false"> <span class="accordion__button__label"> Scientific Research </span> </button> <div class="accordion__panel" id="acc-panel-scientific-research" data-accordion="panel" aria-labelledby="acc-button-scientific-research" role="region"> <ul class="nav text-color-link"> <li><a href="/en/library/scientists-and-research/58/collaborative-research-in-the-arctic-towards-understanding-climate-change/183">Collaborative Research in the Arctic Towards Understanding Climate Change</a></li> <li><a href="/en/library/scientists-and-research/58/from-stable-chromosomes-to-jumping-genes/184">From Stable Chromosomes to Jumping Genes</a></li> <li><a href="/en/library/scientists-and-research/58/an-elegant-experiment-to-test-the-process-of-dna-replication/187">An Elegant Experiment to Test the Process of DNA Replication</a></li> <li><a href="/en/library/scientists-and-research/58/the-founding-of-neuroscience/233">The Founding of Neuroscience</a></li> <li><a href="/en/library/scientists-and-research/58/tracking-endangered-jaguars-across-the-border/189">Tracking Endangered Jaguars across the Border</a></li> <li><a href="/en/library/scientists-and-research/58/atmospheric-chemistry-research-that-changed-global-policy/211">Atmospheric Chemistry Research that Changed Global Policy</a></li> <li><a href="/en/library/scientists-and-research/58/revolutionizing-medicine-with-monoclonal-antibodies/220">Revolutionizing Medicine with Monoclonal Antibodies</a></li> <li><a href="/en/library/scientists-and-research/58/uncovering-the-mysteries-of-chronic-mountain-sickness/238">Uncovering the Mysteries of Chronic Mountain Sickness</a></li> </ul> </div> <button class="accordion__button" id="acc-button-profiles-in-science" data-accordion="button" aria-controls="acc-panel-profiles-in-science" aria-expanded="false"> <span class="accordion__button__label"> Profiles in Science </span> </button> <div class="accordion__panel" id="acc-panel-profiles-in-science" data-accordion="panel" aria-labelledby="acc-button-profiles-in-science" role="region"> <ul class="nav text-color-link"> <li><a href="/en/library/scientists-and-research/58/luis-e.-miramontes/232">Luis E. Miramontes</a></li> <li><a href="/en/library/scientists-and-research/58/bernardo-houssay/237">Bernardo Houssay</a></li> <li><a href="/en/library/scientists-and-research/58/craig-lee/256">Craig Lee</a></li> <li><a href="/en/library/scientists-and-research/58/david-ho/241">David Ho</a></li> <li><a href="/en/library/scientists-and-research/58/louis-tompkins-wright/244">Louis Tompkins Wright</a></li> <li><a href="/en/library/scientists-and-research/58/carlos-j.-finlay/217">Carlos J. Finlay</a></li> <li><a href="/en/library/scientists-and-research/58/cecilia-payne/290">Cecilia Payne</a></li> <li><a href="/en/library/scientists-and-research/58/jazmin-scarlett/291">Jazmin Scarlett</a></li> <li><a href="/en/library/scientists-and-research/58/ramari-stewart/292">Ramari Stewart</a></li> <li><a href="/en/library/scientists-and-research/58/johnson-cerda/300">Johnson Cerda</a></li> <li><a href="/en/library/scientists-and-research/58/ellen-ochoa/201">Ellen Ochoa</a></li> <li><a href="/en/library/scientists-and-research/58/ruth-benerito/205">Ruth Benerito</a></li> <li><a href="/en/library/scientists-and-research/58/franklin-chang-díaz/219">Franklin Chang Díaz</a></li> <li><a href="/en/library/scientists-and-research/58/percy-lavon-julian/221">Percy Lavon Julian</a></li> <li><a href="/en/library/scientists-and-research/58/luis-walter-alvarez/229">Luis Walter Alvarez</a></li> <li><a href="/en/library/scientists-and-research/58/france-anne-dominic-córdova/230">France Anne-Dominic Córdova</a></li> </ul> </div> </div> </div> </div> </div> </li> <li>  <button class="button" data-toggle="dropdown">Earth Science </button> <div class="nav__dropdown box-shadow-1 padding-1"> <div class="accordion accordion--secondary font-size-sm"> <div class="accordion accordion--secondary"> <button class="accordion__button" id="acc-sub-button-plate-tectonics" data-accordion="button" aria-controls="acc-sub-panel-plate-tectonics" aria-expanded="false"> <span class="accordion__button__label"> Plate Tectonics </span> </button> <div class="accordion__panel" id="acc-sub-panel-plate-tectonics" data-accordion="panel" aria-labelledby="acc-sub-button-plate-tectonics" role="region"> <ul class="nav text-color-link"> <li><a href="/en/library/earth-science/6/origins-of-plate-tectonic-theory/65">Origins of Plate Tectonic Theory</a></li> <li><a href="/en/library/earth-science/6/plate-boundaries/66">Plate Boundaries</a></li> <li><a href="/en/library/earth-science/6/earth-structure/69">Earth Structure</a></li> </ul> </div> <button class="accordion__button" id="acc-sub-button-earth-cycles" data-accordion="button" aria-controls="acc-sub-panel-earth-cycles" aria-expanded="false"> <span class="accordion__button__label"> Earth Cycles </span> </button> <div class="accordion__panel" id="acc-sub-panel-earth-cycles" data-accordion="panel" aria-labelledby="acc-sub-button-earth-cycles" role="region"> <ul class="nav text-color-link"> <li><a href="/en/library/earth-science/6/the-rock-cycle/128">The Rock Cycle</a></li> <li><a href="/en/library/earth-science/6/the-hydrologic-cycle/99">The Hydrologic Cycle</a></li> <li><a href="/en/library/earth-science/6/the-carbon-cycle/95">The Carbon Cycle</a></li> <li><a href="/en/library/earth-science/6/the-nitrogen-cycle/98">The Nitrogen Cycle</a></li> <li class="current">The Phosphorus Cycle</li> </ul> </div> <button class="accordion__button" id="acc-sub-button-rocks-and-minerals" 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data-accordion="panel" aria-labelledby="acc-sub-button-atmosphere-and-oceans" role="region"> <ul class="nav text-color-link"> <li><a href="/en/library/earth-science/6/ocean-currents/282">Ocean Currents</a></li> <li><a href="/en/library/earth-science/6/water-in-the-atmosphere/289">Water in the Atmosphere</a></li> <li><a href="/en/library/earth-science/6/weather-fronts-and-forecasts/303">Weather, Fronts, and Forecasts</a></li> <li><a href="/en/library/earth-science/6/history-of-earths-atmosphere-i/202">History of Earth's Atmosphere I</a></li> <li><a href="/en/library/earth-science/6/history-of-earths-atmosphere-ii/203">History of Earth's Atmosphere II</a></li> <li><a href="/en/library/earth-science/6/earths-atmosphere/107">Earth's Atmosphere</a></li> <li><a href="/en/library/earth-science/6/factors-that-control-earths-temperature/234">Factors that Control Earth's Temperature</a></li> <li><a href="/en/library/earth-science/6/circulation-in-the-atmosphere/255">Circulation in the 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href="/en/library/earth-science/6/extinction/295">Extinction</a></li> <li><a href="/en/library/earth-science/6/paleontology-and-the-fossil-record/301">Paleontology and the Fossil Record</a></li> <li><a href="/en/library/earth-science/6/mass-extinctions/294">Mass Extinctions</a></li> </ul> </div> </div> </div> </div> </li> </ul> </nav>  <div id="theTop"></div> <main id="skip-header-content"> <div class="margin-bottom-5"> <div class="container narrow wide--lg margin-y-4"> <article class="module"> <header class="module__header"> <span class="subcategory"> <strong><em>Earth Cycles</em></strong> </span> <h1>The Phosphorus Cycle: <sub><em>Phosphates and fertilizer</em></sub></h1> <p class="byline">by Heather MacNeill Falconer, M.A./M.S.</p> </header> <nav class="module__tabs"> <ul class="tabs-nav tabs-nav--pill tabs-nav--horizontal--md library"> <li> <a href="/en/library/earth-science/6/the-phosphorus-cycle/197/reading" class="is-active" aria-current="page" >Reading</a> </li> <li> <a 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This module describes forms that phosphorous takes in nature and how the element cycles through the natural world. A historical journey highlights how we came to understand this vital element. The Experimental Lakes Project shows the harmful effects of too much phosphorous on the environment as a result of human activities.", "encodingFormat": "mp3", "name": "module_197.mp3" } </script> <div class="module__audio"> <div class="audio-player border border-radius"> <audio id="audio"> <source src="https://www.visionlearning.com/img/library/moduleAudio/module_197.mp3" type="audio/mpeg"> Your browser does not support the audio element. </audio> <div class="audio-player__title"> <p>Listen to this reading</p> <span class="audio-player__timestamp" id="timestamp"> 00:00 </span> </div> <div class="audio-player__controls" id="controls"> <button class="button button--icon-only" id="play-pause-button"> <span class="icon icon-play" aria-hidden="true"></span> </button> <div class="audio-player__progress" id="progress-bar" tabindex="0" aria-valuemin="0" aria-valuemax="100" aria-valuenow="0" aria-label="Use arrow keys to forward or rewind the audio" role="slider"> <div class="audio-player__progress__fill"> <span class="audio-player__thumb"></span> </div> </div> <div class="audio-player__volume-container"> <button id="mute-button"> <span class="icon icon-volume"></span> </button> <div class="audio-player__volume" tabindex="0" aria-valuemin="0" aria-valuemax="100" aria-valuenow="100" aria-label="Use arrow keys to adjust volume" role="slider"> <div class="audio-player__volume__fill"> <span class="audio-player__thumb"></span> </div> </div> </div> </div> </div> </div> <hr class="module__divider" />  <div class="module__tools"> <aside class="module__tools__container border-radius box-shadow-1"> <div class="tabs tabs--toggle-mobile--lg" role="tablist"> <ul class="tab__buttons"> <li> <button class="button button--icon-over-text" aria-label="In this module" aria-controls="tab-panel-module__tools" aria-selected="true" role="tab"> <span class="button__icon"> <span class="icon icon-list" aria-hidden="true"></span> </span> <span class="button__text">Contents</span> </button> </li> <li> <button class="button button--icon-over-text" aria-controls="tab-panel-toggle-terms" aria-selected="false" role="tab"> <span class="button__icon"> <span class="icon icon-glossary-highlight"></span> </span> <span class="button__text">Glossary Terms</span> </button> </li> </ul> <div class="tabs__panel shown" id="tab-panel-module__tools" aria-labelledby="tab-button-module__tools" role="tabpanel"> <div class="table-of-contents"> <p class="table-of-contents__title"> Table of Contents </p> <ul class="table-of-contents__nav"> <li><a href="/en/library/earth-science/6/the-phosphorus-cycle/197#toc_1">The importance of phosphorus to living things</a> </li> <li><a href="/en/library/earth-science/6/the-phosphorus-cycle/197#toc_2">Limitations for growth</a> </li> <li><a href="/en/library/earth-science/6/the-phosphorus-cycle/197#toc_3">Understanding phosphate availability</a> </li> <li><a href="/en/library/earth-science/6/the-phosphorus-cycle/197#toc_4">Phosphorus’ movement through different spheres</a> </li> <li><a href="/en/library/earth-science/6/the-phosphorus-cycle/197#toc_5">The Experimental Lakes Area: A look at the phosphorus cycle in one ecosystem</a> </li> <li> <ul> <li><a href="/en/library/earth-science/6/the-phosphorus-cycle/197#toc2_1">Lakes 227 and 226: Testing limiting nutrients</a> </li> </ul> </li> <li><a href="/en/library/earth-science/6/the-phosphorus-cycle/197#toc_6">Human impacts on the phosphorus cycle</a> </li> </ul> </div> </div> <div class="tabs__panel" id="tab-panel-toggle-terms" aria-labelledby="tab-button-toggle-terms" role="tabpanel"> <div class="reading-toggle"> <div class="reading-toggle__switch"> <div class="form-entry__option__switch"> <label> <input type="checkbox" name="termsToggleSwitch" id="terms-toggle-switch" /> <span class="switch__slider"></span> <span class="option__label text-decoration-none font-size-md"> Highlight Glossary Terms </span> </label> </div> </div> <div class="reading-toggle__help"> <p> <em> Activate glossary term highlighting to easily identify key terms within the module. Once highlighted, you can click on these terms to view their definitions. </em> </p> </div> </div> <div class="glossary-container"></div> </div> <div class="tabs__panel" id="tab-panel-toggle-ngss" aria-labelledby="tab-button-toggle-ngss" role="tabpanel"> <div class="reading-toggle"> <div class="reading-toggle__switch"> <div class="form-entry__option__switch"> <label> <input type="checkbox" name="ngssToggleSwitch" id="ngss-toggle-switch" /> <span class="switch__slider"></span> <span class="option__label text-decoration-none font-size-md"> Show NGSS Annotations </span> </label> </div> </div> <div class="reading-toggle__help"> <p> <em> Activate NGSS annotations to easily identify NGSS standards within the module. Once highlighted, you can click on them to view these standards. </em> </p> </div> </div> <div class="ngss-container"></div> </div> </div> </aside> <div class="margin-3"> <script async src="https://pagead2.googlesyndication.com/pagead/js/adsbygoogle.js?client=ca-pub-9561344156007092" crossorigin="anonymous"></script>  <ins class="adsbygoogle" style="display:block" data-ad-client="ca-pub-9561344156007092" data-ad-slot="7634263342" data-ad-format="auto" data-full-width-responsive="true"></ins> <script> (adsbygoogle = window.adsbygoogle || []).push({}); </script> </div> </div>     <div class="module__main"> <div class="module__main__container"> <div class="accordion">  <button class="accordion__button" id="acc-button-key-concepts" data-accordion="button" aria-controls="acc-panel-key-concepts" aria-expanded="true" tabindex="0"> Did you know? </button> <div class="accordion__panel shown show" id="acc-panel-key-concepts" data-accordion="panel" aria-labelledby="acc-button-key-concepts" role="region"> <div class="accordion__panel__content"> <p>Did you know that plants and animals cannot live without phosphorous, and yet it is one of the most difficult elements for living things to get from nature? Phosphorous is the basis of our teeth and bones and even provides the structure of our DNA. Other important elements are readily available from the atmosphere, but phosphorus occurs only in a liquid or solid state at normal temperatures, so there is less available for organisms to use.</p> </div> </div>  <button class="accordion__button" id="acc-button-table-of-contents" data-accordion="button" aria-controls="acc-panel-table-of-contents" aria-expanded="false" tabindex="0"> Key concepts </button> <div class="accordion__panel" id="acc-panel-table-of-contents" data-accordion="panel" aria-labelledby="acc-button-table-of-contents" role="region" aria-hidden="true"> <div class="accordion__panel__content"> <ul class="bulleted"> <li><p>The phosphorus cycle is the set of biogeochemical processes by which phosphorus undergoes chemical reactions, changes form, and moves through different reservoirs on Earth, including living organisms.</p></li> <li><p>The phosphorus cycle is the only biogeochemical process that does not include a significant gaseous phase. </p></li> <li><p>Phosphorus is required for all organisms to live and grow because it is an essential component of ATP, the structural framework holding DNA and RNA together, cellular membranes, and other critical compounds. </p></li> <li><p>Agricultural runoff, over-fertilization, and sewage all increase the amount of phosphate available to plants and can cause significant ecological damage.</p></li> </ul> </div> </div>  <button class="accordion__button" id="acc-button-terms-you-should-know" data-accordion="button" aria-controls="acc-panel-terms-you-should-know" aria-expanded="false" tabindex="0"> Terms you should know </button> <div class="accordion__panel" id="acc-panel-terms-you-should-know" data-accordion="panel" aria-labelledby="acc-button-terms-you-should-know" role="region" aria-hidden="true"> <div class="accordion__panel__content"> <dl> <dt><a href="/en/glossary/view/ecosystem">ecosystem </a></dt> <dd> the living organisms and nonliving things that exist in a particular environment and function as an interrelated system. </dd> <dt><a href="/en/glossary/view/element">element </a></dt> <dd> a pure chemical substance that is made on only one kind of atom. </dd> <dt><a href="/en/glossary/view/nutrient">nutrient </a></dt> <dd> a source of nourishment that living organisms need to survive and grow.</dd> </dl> </div> </div> </div> <section> <p>For centuries, alchemists around the world searched tirelessly for the philosopher’s stone – a substance rumored to have the ability to turn base metals, like lead, into gold (Figure 1). Like the Holy Grail, stories claimed that this stone was also able to cure illness, prolong life, and even create the user’s clone. The German alchemist Hennig Brand was one such pursuer of the philosopher’s stone. So much so that he completely depleted his first wife’s significant inheritance in his pursuits, and used his second wife’s dowry to do the same!</p>  <div class="figure"> <figure> <button class="lightbox-button" data-lightbox-src="/img/library/large_images/image_6622.jpg" data-lightbox="image"> <img src="/img/library/modules/mid197/Image/VLObject-6622-140512100532.jpg" alt="Figure 1: The Alchemist in Search of the Philosopher's Stone, painting by Joseph Wright of Derby." /> </button> <figcaption> <p><strong>Figure 1:</strong> <em>The Alchemist in Search of the Philosopher's Stone</em>, painting by Joseph Wright of Derby.</p> <span class="credit">image ©Wikimedia Commons</span> </figcaption> </figure> </div> <p>In 1669, Brand was conducting an <mark class="term" data-term="experiment" data-term-def="A test or trial carried out under controlled conditions so that specific actions can be performed and the results can be observed." data-term-url="/en/glossary/view/experiment/8292">experiment</mark> using concentrated urine and sand when he came across something unique. After boiling his mixture down, Brand was left with a white, waxy substance that continued to glow in the dark after it had cooled. At first, he thought that he had discovered the famed stone, but soon discovered this was not the case. What Brand <em>had</em> discovered was phosphorus – one of the most important <mark class="term" data-term="element" data-term-def="One of fewer than 118 pure chemical substances. An element is a substance composed of atoms with identical atomic number." data-term-url="/en/glossary/view/element/1510">elements</mark> to life on Earth.</p> <p><section id="toc_1" class=""> <h2>The importance of phosphorus to living things</h2></p> <p>Like carbon, oxygen, hydrogen, and nitrogen, phosphorus is a <mark class="term" data-term="limiting nutrient" data-term-def="An essential nutrient an organism needs for life that is in the shortest supply in their environment. For example, a tomato&hellip;" data-term-url="/en/glossary/view/limiting+nutrient/7059">limiting nutrient</mark> for all forms of life, which means that the potential for an organism’s growth is limited by the availability of this vital <mark class="term" data-term="nutrient" data-term-def="A chemical substance (e.g., minerals, vitamins, proteins) that is needed by an organism to survive and grow. See also: macronutrient and micronutrient." data-term-url="/en/glossary/view/nutrient/7058">nutrient</mark>. It forms part of the structure of <mark class="term" data-term="DNA" data-term-def="Deoxyribonucleic acid. A double-stranded nucleic acid containing the sugar 2-deoxy-D-ribose. A constituent of cellular nuclear material responsible for encoding&hellip;" data-term-url="/en/glossary/view/DNA/1604">DNA</mark> and <mark class="term" data-term="RNA" data-term-def="Ribonucleic acid. A single-stranded nucleic acid containing the sugar ribose. In most organisms, a molecule responsible for transfer of the&hellip;" data-term-url="/en/glossary/view/RNA/1605">RNA</mark>, is needed for <mark class="term" data-term="energy" data-term-def="An abstract property defined as the capacity to do work. The basic forms of energy include chemical, electrical, mechanical, nuclear, and&hellip;" data-term-url="/en/glossary/view/energy/1497">energy</mark> transport in <mark class="term" data-term="cell" data-term-def="The basic structural unit of all living things." data-term-url="/en/glossary/view/cell/8286">cells</mark>, provides structure to cellular <mark class="term" data-term="membrane" data-term-def="A thin layer of tissue that forms a boundary of a cell or cell part." data-term-url="/en/glossary/view/membrane/8282">membranes</mark>, and assists in giving bones and teeth their rigidity. In short, without phosphorus, we simply could not exist. And yet, for something so crucial, it is one of the most difficult <mark class="term" data-term="element" data-term-def="One of fewer than 118 pure chemical substances. An element is a substance composed of atoms with identical atomic number." data-term-url="/en/glossary/view/element/1510">elements</mark> for living things to access in nature. </p> <div class="container margin-y-4 text-align-center"> <script async src="https://pagead2.googlesyndication.com/pagead/js/adsbygoogle.js?client=ca-pub-9561344156007092" crossorigin="anonymous"></script>  <ins class="adsbygoogle" style="display:inline-block;width:300px;height:250px" data-ad-client="ca-pub-9561344156007092" data-ad-slot="9090201191"></ins> <script> (adsbygoogle = window.adsbygoogle || []).push({}); </script> </div> <p>Prior to the 1800s, very little was known about phosphorus or how it moved through the <mark class="term" data-term="environment" data-term-def="The conditions that surround and affect an organism." data-term-url="/en/glossary/view/environment/8270">environment</mark>. Early chemists like <mark class="term" data-term="Robert Boyle" data-term-def="English chemist and theologian, born at Lismore Castle, Munster, Ireland (1627-1691). Boyle published on a broad array of topics, including chemistry,&hellip;" data-term-url="/en/glossary/view/Boyle%2C+Robert/4459">Robert Boyle</mark> knew that the <mark class="term" data-term="element" data-term-def="One of fewer than 118 pure chemical substances. An element is a substance composed of atoms with identical atomic number." data-term-url="/en/glossary/view/element/1510">element</mark> was highly flammable and would phosphoresce, or glow, when exposed to oxygen. In fact, in 1680 Boyle took advantage of this flammability and developed the first matchstick by using phosphorus to ignite wooden sticks dipped in sulfur. But, like other elements, phosphorus’ contribution to the growth and health of <mark class="term" data-term="organism" data-term-def="Any connected living system, such as an animal, plant, fungus, or bacterium. Organisms may be composed of a single cell or&hellip;" data-term-url="/en/glossary/view/organism/2171">organisms</mark> remained a mystery.</p><p>For almost a century, scientists believed Sir Francis Bacon’s <mark class="term" data-term="hypothesis" data-term-def="From the Greek word <em>hypothesis</em> meaning assumption or the basis of an argument, a hypothesis is a proposal intended to explain&hellip;" data-term-url="/en/glossary/view/hypothesis/3727">hypothesis</mark> that water was the “principle of vegetation” – the essential <mark class="term" data-term="nutrient" data-term-def="A chemical substance (e.g., minerals, vitamins, proteins) that is needed by an organism to survive and grow. See also: macronutrient and micronutrient." data-term-url="/en/glossary/view/nutrient/7058">nutrient</mark> for plant growth (<a href="#refs" onClick="open_refs();">Tindall & Krunkel, 1998</a>). This idea was supported by <mark class="term" data-term="experiment" data-term-def="A test or trial carried out under controlled conditions so that specific actions can be performed and the results can be observed." data-term-url="/en/glossary/view/experiment/8292">experiments</mark> conducted by notable scientists like Jan Baptiste van Helmont, John Evelyn, and <mark class="term" data-term="Robert Boyle" data-term-def="English chemist and theologian, born at Lismore Castle, Munster, Ireland (1627-1691). Boyle published on a broad array of topics, including chemistry,&hellip;" data-term-url="/en/glossary/view/Boyle%2C+Robert/4459">Robert Boyle</mark>. For example, in 1629, the Flemish alchemist van Helmont put Bacon’s <mark class="term" data-term="theory" data-term-def="A scientific theory is an explanation inferred from multiple lines of evidence for some broad aspect of the natural world and&hellip;" data-term-url="/en/glossary/view/theory/4854">theory</mark> to <mark class="term" data-term="Test" data-term-def="This is a test glossary term." data-term-url="/en/glossary/view/Test/12984">test</mark> with his famous willow tree experiment. Van Helmont’s experiment involved the growth of a willow tree in what he thought was a controlled <mark class="term" data-term="environment" data-term-def="The conditions that surround and affect an organism." data-term-url="/en/glossary/view/environment/8270">environment</mark>. In his own words,</p><blockquote class="blockquote"> <p>I took an Earthen vessel, in which I put 200 pounds of Earth that hadbeen [sic] dried in a Furnace, which I moystened with Rainwater, and I implanted therein the Trunk or Stem of a Willow Tree, weighing five pounds; and at length, five years being finished, the Tree sprung from thence, did weigh 169 pounds, and about three ounces: But I moystened the Earthen Vessel with Rain-water, or distilled water (alwayes when there was need) and it was large, and implanted into the Earth, and least the dust that flew about should be co-mingled with the Earth, I covered the lip or mouth of the Vessel with an Iron-Plate covered with Tin, and easily passable with many holes. I computed not the weight of the leaves that fell off in the four Autumnes. At length, I again dried the Earth of the Vessell, and there were found the same two hundred pounds, wanting about two ounces. Therefore 164 pounds of Wood, Barks, and Roots, arose out of water onely. (van Helmont, 1662)</p> </p></blockquote><p>We now know that there were flaws in van Helmont’s <mark class="term" data-term="experiment" data-term-def="A test or trial carried out under controlled conditions so that specific actions can be performed and the results can be observed." data-term-url="/en/glossary/view/experiment/8292">experiment</mark>, including his use of <mark class="term" data-term="soil" data-term-def="The loose top layer of Earth’s surface where plants grow, made up of particles of rocks, minerals, and organic material." data-term-url="/en/glossary/view/soil/8563">soil</mark> in an application meant to show that water alone was what nourished plants. However, his contributions to our knowledge of the role of <mark class="term" data-term="element" data-term-def="One of fewer than 118 pure chemical substances. An element is a substance composed of atoms with identical atomic number." data-term-url="/en/glossary/view/element/1510">elements</mark> in plant nutrition were significant. The willow tree experiment alone marked the beginning of experimental plant physiology, and is both one of the first quantitative experiments in biology and one of the first written accounts of the use of the scientific <mark class="term" data-term="method" data-term-def="A procedure or process; a systematic way of performing a task or conducting research." data-term-url="/en/glossary/view/method/8238">method</mark> (Hershey, 2003; Morton, 1981).</p><p>During the 17<sup>th</sup> century, however, a German chemist named Johann Glauber argued that <mark class="term" data-term="soil" data-term-def="The loose top layer of Earth’s surface where plants grow, made up of particles of rocks, minerals, and organic material." data-term-url="/en/glossary/view/soil/8563">soil</mark>, not water, was the sole source of <mark class="term" data-term="nourish" data-term-url="/en/glossary/view/nourish" data-term-def="The act of providing an organism with nutrients.">nourishment</mark> for plants. This sparked a <mark class="term" data-term="debate" data-term-def="A reasoned discussion of opposing points in an argument." data-term-url="/en/glossary/view/debate/8242">debate</mark> that continued in various forms into the 18<sup>th</sup> century. In 1775, Frances Home concluded that both arguments were correct. Home theorized that not one but many factors influence a plant’s growth – a conclusion that would open up new <mark class="term" data-term="research" data-term-def="A study or an investigation." data-term-url="/en/glossary/view/research/8257">research</mark> in various fields.</p></section> <section id="toc_2"> <h2>Limitations for growth</h2><p>In 1838, a competition was held by The Academy of Sciences in Göttingen, Germany (Tindall & Krunkel, 1998). The Academy asked members of the scientific community to determine whether the <mark class="term" data-term="inorganic" data-term-def="Not originating from a living organism; not a compound that contains hydrocarbons." data-term-url="/en/glossary/view/inorganic/8521">inorganic</mark> <mark class="term" data-term="element" data-term-def="One of fewer than 118 pure chemical substances. An element is a substance composed of atoms with identical atomic number." data-term-url="/en/glossary/view/element/1510">elements</mark> found in the ashes of plants are present in the living plant, and whether there was any <mark class="term" data-term="evidence" data-term-def="Support for an idea, opinion, or hypothesis." data-term-url="/en/glossary/view/evidence/8243">evidence</mark> of these inorganic elements being necessary for plant growth and survival. Justus von Liebig, a German chemist, won the contest with his treatise <em>Organic Chemistry and its Applications to Agriculture and Physiology</em> (von Liebig, 1838).</p><p>Von Liebig explained that certain <mark class="term" data-term="element" data-term-def="One of fewer than 118 pure chemical substances. An element is a substance composed of atoms with identical atomic number." data-term-url="/en/glossary/view/element/1510">elements</mark>, like Carbon (C), Hydrogen (H), and Phosphorus (P), are vital to the growth and sustainability of plants. His work drew clear connections between crop yield and the amount of fertilizer offered during the growing season, and identified a hierarchy of <mark class="term" data-term="mineral" data-term-def="A naturally formed, inorganic solid with a specific chemical composition and characteristic crystal structure. Examples of minerals include quartz (SiO<sub>2</sub>), salt&hellip;" data-term-url="/en/glossary/view/mineral/2978">minerals</mark> in these interactions. One of the most important moments in von Liebig’s work is a discussion of the “Law of Minimum.”</p><p>The <mark class="term" data-term="law" data-term-def="In science, a principle that describes a phenomenon, often mathematically." data-term-url="/en/glossary/view/law/8686">Law</mark> of Minimum states that the growth and yield of a plant are limited by the <mark class="term" data-term="nutrient" data-term-def="A chemical substance (e.g., minerals, vitamins, proteins) that is needed by an organism to survive and grow. See also: macronutrient and micronutrient." data-term-url="/en/glossary/view/nutrient/7058">nutrient</mark> in least abundance, regardless of which nutrient that might be. This law is often referred to as Liebig’s Law of Minimum, though it is understood now that the discovery actually belongs to Karl Sprengel, a German <mark class="term" data-term="agronomist" data-term-def="A scientist whose focus is the management of soil and the production of crops. Agronomy includes the study of farming practices:&hellip;" data-term-url="/en/glossary/view/agronomist/7062">agronomist</mark> working at the same time. Because <mark class="term" data-term="macronutrient" data-term-def="Nutrients that are needed in high amounts to sustain life. For example, plants need a high amount of nitrogen, phosphorus, and&hellip;" data-term-url="/en/glossary/view/macronutrient/7075">macronutrients</mark> like carbon, oxygen, hydrogen, and nitrogen are readily available in Earth’s <mark class="term" data-term="atmosphere" data-term-def="The collective mass of gases that surrounds the Earth or another planet." data-term-url="/en/glossary/view/atmosphere/8529">atmosphere</mark>, more often than not the <mark class="term" data-term="limiting nutrient" data-term-def="An essential nutrient an organism needs for life that is in the shortest supply in their environment. For example, a tomato&hellip;" data-term-url="/en/glossary/view/limiting+nutrient/7059">limiting nutrient</mark> for plant growth in natural <mark class="term" data-term="ecosystem" data-term-def="The complex of a community of organisms and its environment, functioning as a unit." data-term-url="/en/glossary/view/ecosystem/2174">ecosystems</mark> is phosphorus.</p> <div class="comprehension-checkpoint margin-y-4"> <h6 class="comprehension-checkpoint__header"> <span> <span class="icon icon-question"></span> </span> Comprehension Checkpoint </h6> <form name="cc6632"> <div class="form-entry"> <div class="form-entry__field"> <span class="form-entry__field__label">According to the Law of Minimum</span> <div class="form-entry__option"> <div class="form-entry__option__radio" data-answer="incorrect"> <label> <input id="q1-6632-0-option-a" name="quiz-option-6632" type="radio" value="the smallest plants need the most nutrients in order to grow." > <span class="option__label"> <span class="screen-reader-only">a.</span> the smallest plants need the most nutrients in order to grow. </span> </label> <span class="quiz__response" id="response-6632-0"> <strong>Incorrect.</strong> </span> </div> <div class="form-entry__option__radio" data-answer="correct"> <label> <input id="q1-6632-1-option-b" name="quiz-option-6632" type="radio" value="plant growth is limited by the nutrient that is least plentiful." > <span class="option__label"> <span class="screen-reader-only">b.</span> plant growth is limited by the nutrient that is least plentiful. </span> </label> <span class="quiz__response" id="response-6632-1"> <strong>Correct!</strong> </span> </div> </div> </div> </div> </form> </div> </section> <section id="toc_3"> <h2>Understanding phosphate availability</h2><p>Like many of Earth’s cycles, the phosphorus cycle involves movement through biological and geological <mark class="term" data-term="system" data-term-def="A group of interacting, interrelated or interdependent components that form a complex whole. The size of the system is defined for&hellip;" data-term-url="/en/glossary/view/system/3904">systems</mark>, and this movement is driven by various chemical transformations. Unlike carbon or nitrogen, however, phosphorus moves only through the <mark class="term" data-term="lithosphere" data-term-def="The rigid upper layer of Earth consisting of the crust and the upper mantle. Earth’s tectonic plates are composed of pieces&hellip;" data-term-url="/en/glossary/view/lithosphere/1666">lithosphere</mark>, <mark class="term" data-term="biosphere" data-term-def="All of the living organisms on Earth." data-term-url="/en/glossary/view/biosphere/2177">biosphere</mark>, and <mark class="term" data-term="hydrosphere" data-term-def="All the water available on Earth and within Earth’s atmosphere, including (but not limited to) lakes, rivers, oceans, glaciers, aquifers, ice&hellip;" data-term-url="/en/glossary/view/hydrosphere/7063">hydrosphere</mark>. It is one of the only <mark class="term" data-term="biogeochemical" data-term-def="Of or relating to the partitioning and cycling of chemical elements and compounds between the living and nonliving parts of an ecosystem." data-term-url="/en/glossary/view/biogeochemical/2179">biogeochemical</mark> cycles that does not involve a gaseous stage, meaning that it does not become part of Earth’s <mark class="term" data-term="atmosphere" data-term-def="The collective mass of gases that surrounds the Earth or another planet." data-term-url="/en/glossary/view/atmosphere/8529">atmosphere</mark> in any significant way.</p>  <div class="figure"> <figure> <button class="lightbox-button" data-lightbox-src="/img/library/large_images/image_6666.jpg" data-lightbox="image"> <img src="/img/library/modules/mid197/Image/VLObject-6666-140516120559.jpg" alt="Figure 2: Phosphates are a biological molecule that play an important role in the structure and function of living things. They contain at least one phosphorus atom bound to four oxygen atoms, but will bond with other atoms (like hydrogen) to create a wide variety of compounds necessary for life." /> </button> <figcaption> <p><strong>Figure 2:</strong> Phosphates are a biological molecule that play an important role in the structure and function of living things. They contain at least one phosphorus atom bound to four oxygen atoms, but will bond with other atoms (like hydrogen) to create a wide variety of compounds necessary for life.</p> </figcaption> </figure> </div> <p>As Brand discovered, elemental phosphorus is a highly reactive substance. Simply exposing it to air will stimulate a <mark class="term" data-term="chemical reaction" data-term-def="A process in which atoms and molecules recombine by forming or breaking chemical bonds. Chemical reactions form new products that&hellip;" data-term-url="/en/glossary/view/chemical+reaction/1547">chemical reaction</mark> with oxygen. This means that in nature the <mark class="term" data-term="element" data-term-def="One of fewer than 118 pure chemical substances. An element is a substance composed of atoms with identical atomic number." data-term-url="/en/glossary/view/element/1510">element</mark> is typically found as a phosphate ($PO_4^{-3}$). Phosphates, in their most basic form, contain one phosphorus <mark class="term" data-term="atom" data-term-def="The smallest unit of an element that retains the chemical properties of the element. Atoms can exist alone or in&hellip;" data-term-url="/en/glossary/view/atom/1509">atom</mark> bound to four oxygen atoms, with one of those oxygen atoms being bonded to another atom, like hydrogen (Figure 2). A very common phosphate found in nature, for example, is $HPO_4^{-2}$. There are a wide variety of combinations that take place with this simple $PO_4^{-3}$ anion: <mark class="term" data-term="bonding" data-term-def="The act of fastening two atoms together." data-term-url="/en/glossary/view/bonding/8295">bonding</mark> with carbon, nitrogen, and hydrogen to create the <mark class="term" data-term="energy" data-term-def="An abstract property defined as the capacity to do work. The basic forms of energy include chemical, electrical, mechanical, nuclear, and&hellip;" data-term-url="/en/glossary/view/energy/1497">energy</mark> storage <mark class="term" data-term="compound" data-term-def="A material formed by the chemical combination of elements in defined proportions. Compounds can be chemically decomposed into simpler substances." data-term-url="/en/glossary/view/compound/1517">compound</mark> <mark class="term" data-term="adenosine triphosphate" data-term-url="/en/glossary/view/adenosine+triphosphate" data-term-def="(ATP) Molecules that provide energy for important chemical reactions within the cell; the main energy currency of the cell.">ATP</mark>, for example, or with calcium (and occasionally hydrogen) to create calcium phosphate (Figure 3). <mark class="term" data-term="DNA" data-term-def="Deoxyribonucleic acid. A double-stranded nucleic acid containing the sugar 2-deoxy-D-ribose. A constituent of cellular nuclear material responsible for encoding&hellip;" data-term-url="/en/glossary/view/DNA/1604">DNA</mark>, our genetic <mark class="term" data-term="blueprint" data-term-def="A detailed outline or plan of action. The word technically refers to a process of photographic printing, used chiefly in copying&hellip;" data-term-url="/en/glossary/view/blueprint/5295">blueprint</mark>, relies on phosphate groups to provide the backbone to its double-helix structure (see our <a href="/en/library/Biology/2/DNA-II/160">DNA II: The Structure of DNA</a> module for more information), and <mark class="term" data-term="cell" data-term-def="The basic structural unit of all living things." data-term-url="/en/glossary/view/cell/8286">cell</mark> <mark class="term" data-term="membrane" data-term-def="A thin layer of tissue that forms a boundary of a cell or cell part." data-term-url="/en/glossary/view/membrane/8282">membranes</mark> rely on <mark class="term" data-term="phospholipid" data-term-def="A lipid or glyceride that contains a phosphate group. The phosphate group imparts a polar side to the molecule, while&hellip;" data-term-url="/en/glossary/view/phospholipid/2567">phospholipids</mark> to give them structure (see our <a href="/en/library/Biology/2/Membranes-I/198">Membranes I: Introduction to Biological Membranes</a> module).</p>  <div class="figure"> <figure> <button class="lightbox-button" data-lightbox="image"> <img src="/img/library/modules/mid197/Image/VLObject-7078-140807020856.jpg" alt="Figure 3: Adenosine Tri-Phosphate (ATP) is responsible for the transport of chemical energy within cells for metabolism, and calcium phosphate is a primary component of milk, bones, and teeth." /> </button> <figcaption> <p><strong>Figure 3</strong>: Adenosine Tri-Phosphate (ATP) is responsible for the transport of chemical energy within cells for metabolism, and calcium phosphate is a primary component of milk, bones, and teeth.</p> </figcaption> </figure> </div> <p>In the <mark class="term" data-term="environment" data-term-def="The conditions that surround and affect an organism." data-term-url="/en/glossary/view/environment/8270">environment</mark>, phosphates can be found in both <mark class="term" data-term="organic" data-term-def="Originating from a living organism; a compound that contains hydrocarbons." data-term-url="/en/glossary/view/organic/8530">organic</mark> and <mark class="term" data-term="inorganic" data-term-def="Not originating from a living organism; not a compound that contains hydrocarbons." data-term-url="/en/glossary/view/inorganic/8521">inorganic</mark> forms. Organic phosphates are mainly created through biological processes and include a bonded carbon, such as in plant or animal tissues. Inorganic phosphates on the other hand, are not associated with carbon. They are produced through natural processes like chemical <mark class="term" data-term="weathering" data-term-def="The destructive processes that change the physical and chemical characteristics of rocks at the earth's surface. Physical breakdown of large rocks&hellip;" data-term-url="/en/glossary/view/weathering/2277">weathering</mark> of phosphorous-containing rocks, or man-made processes like the chemical manufacturing of fertilizers. While animals are able to use either of these forms, plants are able to use only the inorganic form. </p> <div class="comprehension-checkpoint margin-y-4"> <h6 class="comprehension-checkpoint__header"> <span> <span class="icon icon-question"></span> </span> Comprehension Checkpoint </h6> <form name="cc6637"> <div class="form-entry"> <div class="form-entry__field"> <span class="form-entry__field__label">Phosphorous is most often found</span> <div class="form-entry__option"> <div class="form-entry__option__radio" data-answer="correct"> <label> <input id="q1-6637-0-option-a" name="quiz-option-6637" type="radio" value="combined with other elements as phosphates." > <span class="option__label"> <span class="screen-reader-only">a.</span> combined with other elements as phosphates. </span> </label> <span class="quiz__response" id="response-6637-0"> <strong>Correct!</strong> </span> </div> <div class="form-entry__option__radio" data-answer="incorrect"> <label> <input id="q1-6637-1-option-b" name="quiz-option-6637" type="radio" value="in its elemental form as pure phosphorous." > <span class="option__label"> <span class="screen-reader-only">b.</span> in its elemental form as pure phosphorous. </span> </label> <span class="quiz__response" id="response-6637-1"> <strong>Incorrect.</strong> </span> </div> </div> </div> </div> </form> </div> </section> <section id="toc_4"> <h2>Phosphorus’ movement through different spheres</h2><p>The phosphorus cycle is similar to other elemental cycles and is often described in an overly-simplified way: As Earth’s tectonic plates shift, volcanic action, <mark class="term" data-term="earthquake" data-term-def="1. The sudden motion or slip along a fault. 2. The ground shaking that results from the release of seismic energy&hellip;" data-term-url="/en/glossary/view/earthquake/1664">earthquakes</mark>, and movement at plate boundaries expose buried <mark class="term" data-term="sediment" data-term-def="Loose, unconsolidated material of the following compositions: <br> 1. rock fragments (also called clasts) transported by wind, moving water,&hellip;" data-term-url="/en/glossary/view/sediment/3310">sediments</mark> and rock to the <mark class="term" data-term="surface" data-term-def="The outside or external part; the topside face of something." data-term-url="/en/glossary/view/surface/8275">surface</mark> of the planet (to learn more, read our <a href="/library/module_viewer.php?mid=66">Plates, Plate Boundaries, and Driving Forces</a> and <a href="/library/module_viewer.php?mid=128">The Rock Cycle: Uniformitarianism and Recycling</a> modules). When exposed to <mark class="term" data-term="element" data-term-def="One of fewer than 118 pure chemical substances. An element is a substance composed of atoms with identical atomic number." data-term-url="/en/glossary/view/element/1510">elements</mark> like wind and water, <mark class="term" data-term="mechanical" data-term-def="Involving physical force or motion." data-term-url="/en/glossary/view/mechanical/8516">mechanical</mark> and chemical <mark class="term" data-term="weathering" data-term-def="The destructive processes that change the physical and chemical characteristics of rocks at the earth's surface. Physical breakdown of large rocks&hellip;" data-term-url="/en/glossary/view/weathering/2277">weathering</mark> of these rocks take place. These transformations release phosphates that have been bound in these reservoirs to the <mark class="term" data-term="environment" data-term-def="The conditions that surround and affect an organism." data-term-url="/en/glossary/view/environment/8270">environment</mark>, where they become available in <mark class="term" data-term="soil" data-term-def="The loose top layer of Earth’s surface where plants grow, made up of particles of rocks, minerals, and organic material." data-term-url="/en/glossary/view/soil/8563">soil</mark> and water. After passing through biological <mark class="term" data-term="system" data-term-def="A group of interacting, interrelated or interdependent components that form a complex whole. The size of the system is defined for&hellip;" data-term-url="/en/glossary/view/system/3904">systems</mark> via the food chain, phosphorus is eventually returned to the soil and then into <mark class="term" data-term="aquatic" data-term-def="Related to, located in, or living in or on a body of water. Not terrestrial. Aquatic includes both freshwater and saltwater&hellip;" data-term-url="/en/glossary/view/aquatic/5619">aquatic</mark> systems, where it ultimately becomes sediment and can move back into the geological part of the cycle (Figure 4).</p>  <div class="figure"> <figure> <button class="lightbox-button" data-lightbox-src="/img/library/large_images/image_6668.jpg" data-lightbox="image"> <img src="/img/library/modules/mid197/Image/VLObject-6668-140516010506.jpg" alt="Figure 4: A simplified drawing of the phosphorus cycle. Phosphorus moves in multiple directions through a series of smaller processes." /> </button> <figcaption> <p><strong>Figure 4:</strong> A simplified drawing of the phosphorus cycle. Phosphorus moves in multiple directions through a series of smaller processes.</p> </figcaption> </figure> </div> <div class="container margin-y-4 text-align-center"> <script async src="https://pagead2.googlesyndication.com/pagead/js/adsbygoogle.js?client=ca-pub-9561344156007092" crossorigin="anonymous"></script>  <ins class="adsbygoogle" style="display:inline-block;width:300px;height:250px" data-ad-client="ca-pub-9561344156007092" data-ad-slot="3321739899"></ins> <script> (adsbygoogle = window.adsbygoogle || []).push({}); </script> </div> <p>Like all of Earth’s cycles, there is no start or finish to the phosphorus cycle, and certainly no single direction of movement. Earth’s cycles are complex webs where resources move in multiple directions. In fact, it might be even easier to think of the phosphorus cycle as being a <mark class="term" data-term="process" data-term-def="Method, procedure; series of actions or steps." data-term-url="/en/glossary/view/process/8256">process</mark> made up of a series of smaller processes that may or may not ever interact – processes that take place over a time frame as short as weeks and as long as millennia. To get a better sense of the movement of phosphorus through the <mark class="term" data-term="lithosphere" data-term-def="The rigid upper layer of Earth consisting of the crust and the upper mantle. Earth’s tectonic plates are composed of pieces&hellip;" data-term-url="/en/glossary/view/lithosphere/1666">lithosphere</mark>, <mark class="term" data-term="biosphere" data-term-def="All of the living organisms on Earth." data-term-url="/en/glossary/view/biosphere/2177">biosphere</mark>, and <mark class="term" data-term="hydrosphere" data-term-def="All the water available on Earth and within Earth’s atmosphere, including (but not limited to) lakes, rivers, oceans, glaciers, aquifers, ice&hellip;" data-term-url="/en/glossary/view/hydrosphere/7063">hydrosphere</mark>, it helps to view it in terms of its movement on a shorter time-scale and through a specific <mark class="term" data-term="ecosystem" data-term-def="The complex of a community of organisms and its environment, functioning as a unit." data-term-url="/en/glossary/view/ecosystem/2174">ecosystem</mark>.</p></section> <section id="toc_5"> <h2>The Experimental Lakes Area: A look at the phosphorus cycle in one ecosystem</h2><p>During the months of September and October 1967, scientists T.R. Cleugh and B.W. Hauser began a helicopter survey on 463 lakes in the Precambrian Shield in northwestern Ontario, Canada (Figure 5). Lakes were numbered in the order they were sampled, and <mark class="term" data-term="data" data-term-def="(plural form of <b>datum</b>) A collection of pieces of information, generally taking the form of numbers, text, bits, or facts, that&hellip;" data-term-url="/en/glossary/view/data/3729">data</mark> on <mark class="term" data-term="maximum depth" data-term-def="In aquatic sciences, the deepest part of a specified area, such as a lake or gulf. Depth is an important factor&hellip;" data-term-url="/en/glossary/view/maximum+depth/7064">maximum depth</mark>, <mark class="term" data-term="visibility" data-term-def="The distance the human eye can see through a given medium, such as air or water, under certain environmental conditions. <br> <br> In aquatic&hellip;" data-term-url="/en/glossary/view/visibility/7065">visibility</mark>, <mark class="term" data-term="dissolved solid" data-term-def="Organic and inorganic substances that have dissolved into a volume of water. Dissolved solids include salts, minerals, and other materials that&hellip;" data-term-url="/en/glossary/view/dissolved+solid/7066">dissolved solids</mark>, and <mark class="term" data-term="conductivity" data-term-def="A measurement of a substance’s ability to transmit (or conduct) heat, sound, or electricity. For example, copper exhibits high conductivity&hellip;" data-term-url="/en/glossary/view/conductivity/7067">conductivity</mark> were recorded to create lake profiles (Cleugh & Hauser, 1971). This was the first step in what would become one of the most well-known examples of extreme science: the creation of the Experimental Lakes Area (ELA), a project run by the Freshwater Institute to manipulate whole-lake <mark class="term" data-term="ecosystem" data-term-def="The complex of a community of organisms and its environment, functioning as a unit." data-term-url="/en/glossary/view/ecosystem/2174">ecosystems</mark>.</p>  <div class="figure"> <figure> <button class="lightbox-button" data-lightbox-src="/img/library/large_images/image_7027.jpg" data-lightbox="image"> <img src="/img/library/modules/mid197/Image/VLObject-7027-140624090631.jpg" alt="Figure 5: Map of the Precambrian Shield" /> </button> <figcaption> <p><strong>Figure 5</strong>: Map of the Precambrian Shield</p> </figcaption> </figure> </div> <p>The Experimental Lakes Project had its beginnings in 1965 when the US and Canadian governments were asked by the International Joint Commission (IJC), a commission that helps Canada and the US prevent disputes over <mark class="term" data-term="boundary" data-term-def="A line or limit that divides one area from another." data-term-url="/en/glossary/view/boundary/8272">boundary</mark> waters, to devote resources to understanding pollution in the lower Great Lakes/St. Lawrence Plain. This unique region – spanning the southern part of Ontario to areas of central New York, Vermont, Pennsylvania, and Ohio – had been transformed during the early 20<sup>th</sup> century from forests rich in oak, hemlock, and mixed-conifers to land primarily devoted to agriculture. Housing <mark class="term" data-term="development" data-term-def="The gradual exposure to stimuli in the early-developmental stages that influences the size, shape, and function of animal once mature." data-term-url="/en/glossary/view/development/13147">developments</mark> throughout the region also increased significantly over this time. The water bodies of interest to the IJC were beginning to show effects of <mark class="term" data-term="eutrophication" data-term-def="A process of excessive plant growth in a water body (usually phytoplankton) in response to an influx of nutrients. The excessive&hellip;" data-term-url="/en/glossary/view/eutrophication/7069">eutrophication</mark> – a condition of excessive plant and <mark class="term" data-term="algae" data-term-def="(plural form of <b>alga</b>) Mostly aquatic plantlike organisms that range in size from one cell to large multi-celled seaweed and are photosynthetic." data-term-url="/en/glossary/view/algae/8678">algae</mark> growth that can kill fish and other wildlife in the water – and little to no information existed on the causes or <mark class="term" data-term="control" data-term-def="In science, a control is a system for which the expected change or outcome is well known and is measured or&hellip;" data-term-url="/en/glossary/view/control/3801">controls</mark>.</p><p>As a result, the Experimental Lakes Area was created to study these questions. It consisted of isolated, pristine land containing 58 lakes and watersheds, free from cultural or industrial influence, where researchers could actively manipulate whole <mark class="term" data-term="ecosystem" data-term-def="The complex of a community of organisms and its environment, functioning as a unit." data-term-url="/en/glossary/view/ecosystem/2174">ecosystems</mark>. The first <mark class="term" data-term="experiment" data-term-def="A test or trial carried out under controlled conditions so that specific actions can be performed and the results can be observed." data-term-url="/en/glossary/view/experiment/8292">experiments</mark> involved researchers directly controlling <mark class="term" data-term="nutrient" data-term-def="A chemical substance (e.g., minerals, vitamins, proteins) that is needed by an organism to survive and grow. See also: macronutrient and micronutrient." data-term-url="/en/glossary/view/nutrient/7058">nutrient</mark> influxes to isolate the factors that might influence <mark class="term" data-term="eutrophication" data-term-def="A process of excessive plant growth in a water body (usually phytoplankton) in response to an influx of nutrients. The excessive&hellip;" data-term-url="/en/glossary/view/eutrophication/7069">eutrophication</mark> in the water bodies. One of the experiments – that on Lake 227 – was conducted over the course of 44 years. It and a shorter experiment in Lake 226 were the first of their kind to clearly identify phosphorus as a driving factor in eutrophication.</p> <div class="comprehension-checkpoint margin-y-4"> <h6 class="comprehension-checkpoint__header"> <span> <span class="icon icon-question"></span> </span> Comprehension Checkpoint </h6> <form name="cc6645"> <div class="form-entry"> <div class="form-entry__field"> <span class="form-entry__field__label">Excessive algae growth</span> <div class="form-entry__option"> <div class="form-entry__option__radio" data-answer="correct"> <label> <input id="q1-6645-0-option-a" name="quiz-option-6645" type="radio" value="can end up killing fish." > <span class="option__label"> <span class="screen-reader-only">a.</span> can end up killing fish. </span> </label> <span class="quiz__response" id="response-6645-0"> <strong>Correct!</strong> </span> </div> <div class="form-entry__option__radio" data-answer="incorrect"> <label> <input id="q1-6645-1-option-b" name="quiz-option-6645" type="radio" value="helps fish to thrive." > <span class="option__label"> <span class="screen-reader-only">b.</span> helps fish to thrive. </span> </label> <span class="quiz__response" id="response-6645-1"> <strong>Incorrect.</strong> </span> </div> </div> </div> </div> </form> </div> </section> <section id="toc2_1"><h3>Lakes 227 and 226: Testing limiting nutrients</h3><p>Lake 227 is small by most lake standards and offered <mark class="term" data-term="limnologist" data-term-def="A scientist whose focus is the study of inland water bodies (e.g., lakes, rivers, streams) and their surrounding environment. This includes&hellip;" data-term-url="/en/glossary/view/limnologist/7073">limnologist</mark> David W. Schindler and his <mark class="term" data-term="research" data-term-def="A study or an investigation." data-term-url="/en/glossary/view/research/8257">research</mark> team an ideal <mark class="term" data-term="subject" data-term-def="A person or animal used in a research study." data-term-url="/en/glossary/view/subject/8252">subject</mark> on which to <mark class="term" data-term="Test" data-term-def="This is a test glossary term." data-term-url="/en/glossary/view/Test/12984">test</mark> their ideas about <mark class="term" data-term="eutrophication" data-term-def="A process of excessive plant growth in a water body (usually phytoplankton) in response to an influx of nutrients. The excessive&hellip;" data-term-url="/en/glossary/view/eutrophication/7069">eutrophication</mark>. In June 1969, Schindler and his team began to intentionally fertilize Lake 227 on a weekly basis, using a fertilizer with a 12:1 <mark class="term" data-term="ratio" data-term-def="The relationship between two or more quantities; relative amounts of two or more values expressed as a proportion." data-term-url="/en/glossary/view/ratio/8556">ratio</mark> by weight of nitrogen to phosphorus (Schindler, 2008). At the time, they were interested in testing a <mark class="term" data-term="hypothesis" data-term-def="From the Greek word <em>hypothesis</em> meaning assumption or the basis of an argument, a hypothesis is a proposal intended to explain&hellip;" data-term-url="/en/glossary/view/hypothesis/3727">hypothesis</mark> popular in North America that the supply of carbon could limit the growth of <mark class="term" data-term="phytoplankton" data-term-def="Microscopic plants, such as algae, that float freely in the water column of an aquatic system (e.g., lake, ocean)." data-term-url="/en/glossary/view/phytoplankton/7074">phytoplankton</mark> in lakes. They chose Lake 227 specifically because it had a low <mark class="term" data-term="concentration" data-term-def="The amount of one substance in relation to other components within a given area." data-term-url="/en/glossary/view/concentration/8733">concentration</mark> of dissolved <mark class="term" data-term="inorganic" data-term-def="Not originating from a living organism; not a compound that contains hydrocarbons." data-term-url="/en/glossary/view/inorganic/8521">inorganic</mark> carbon (Schindler, 2009). For the first five years of the <mark class="term" data-term="experiment" data-term-def="A test or trial carried out under controlled conditions so that specific actions can be performed and the results can be observed." data-term-url="/en/glossary/view/experiment/8292">experiment</mark>, the researchers added phosphorus and nitrogen to the lake to ensure phytoplankton had adequate amounts for growth and sustainability, but limited access to carbon.</p>  <div class="figure"> <figure> <button class="lightbox-button" data-lightbox-src="/img/library/large_images/image_6664.jpg" data-lightbox="image"> <img src="/img/library/modules/mid197/Image/VLObject-6664-140516120519.jpg" alt="Figure 6: The data from Schindler's research shows a clear connection between the amount of phosphorus added to the lakes and the algal growth." /> </button> <figcaption> <p><strong>Figure 6:</strong> The data from Schindler's research shows a clear connection between the amount of phosphorus added to the lakes and the algal growth.</p> <span class="credit">image ©David W. Schindler</span> </figcaption> </figure> </div> <p>After nutrient-loading Lake 227 for the first time, Schindler and his team noticed that <mark class="term" data-term="algae" data-term-def="(plural form of <b>alga</b>) Mostly aquatic plantlike organisms that range in size from one cell to large multi-celled seaweed and are photosynthetic." data-term-url="/en/glossary/view/algae/8678">algae</mark> growth increased significantly (or “bloomed”) despite the low <mark class="term" data-term="concentration" data-term-def="The amount of one substance in relation to other components within a given area." data-term-url="/en/glossary/view/concentration/8733">concentration</mark> of carbon. Further, they saw that the blooms had a direct <mark class="term" data-term="correlation" data-term-def="Correlation, as measured by the correlation coefficient, provides a measure of the strength and direction of a linear relationship between two&hellip;" data-term-url="/en/glossary/view/correlation/3912">correlation</mark> to the amount of phosphorus they added to the water (Figure 6). While Schindler began to suspect phosphorous as the culprit, he needed further <mark class="term" data-term="evidence" data-term-def="Support for an idea, opinion, or hypothesis." data-term-url="/en/glossary/view/evidence/8243">evidence</mark>. Importantly, the soap and detergent industry, whose <mark class="term" data-term="product" data-term-def="The material that is formed as a result of a chemical reaction. Written on the right side of a chemical equation.&hellip;" data-term-url="/en/glossary/view/product/1569">products</mark> contained phosphorous, worked to take the focus off of the phosphorous-containing products by arguing that nitrogen was as influential in <mark class="term" data-term="aquatic" data-term-def="Related to, located in, or living in or on a body of water. Not terrestrial. Aquatic includes both freshwater and saltwater&hellip;" data-term-url="/en/glossary/view/aquatic/5619">aquatic</mark> <mark class="term" data-term="system" data-term-def="A group of interacting, interrelated or interdependent components that form a complex whole. The size of the system is defined for&hellip;" data-term-url="/en/glossary/view/system/3904">systems</mark> as phosphorus. So, the team began to <mark class="term" data-term="Test" data-term-def="This is a test glossary term." data-term-url="/en/glossary/view/Test/12984">test</mark> the effects of nitrogen separately by adding nitrogen and carbon to Lake 226.</p>  <div class="figure"> <figure> <button class="lightbox-button" data-lightbox="image"> <img src="/img/library/modules/mid197/Image/VLObject-6665-140516120524.jpg" alt="Figure 7: An aerial photograph of Lake 226 taken in August 1973. The plastic curtain dividing the lake at the narrows allowed Schindler's team to nutrient load each half of the lake with different amounts of phosphates. The northern basin, shown on the bottom half of the photo, became eutrophic in response to the excess phosphorus." /> </button> <figcaption> <p><strong>Figure 7:</strong> An aerial photograph of Lake 226 taken in August 1973. The plastic curtain dividing the lake at the narrows allowed Schindler's team to nutrient load each half of the lake with different amounts of phosphates. The northern basin, shown on the bottom half of the photo, became eutrophic in response to the excess phosphorus.</p> <span class="credit">image ©David W. Schindler</span> </figcaption> </figure> </div> <p>Lake 226, shaped like an hourglass, had two basins that could be isolated from one another at the narrows with a heavy nylon curtain (Figure 7). Schindler’s group added nitrogen and carbon to both of the basins, but in the north basin they also added phosphorus. Again, algal blooms were in direct relation to the amount of phosphorus added – the south basin remained pristine, while the north basin bloomed within weeks (Schindler, 1977).</p><p>Schindler’s <mark class="term" data-term="research" data-term-def="A study or an investigation." data-term-url="/en/glossary/view/research/8257">research</mark> began to show clearly that phosphorus, and not carbon or nitrogen, is the <mark class="term" data-term="nutrient" data-term-def="A chemical substance (e.g., minerals, vitamins, proteins) that is needed by an organism to survive and grow. See also: macronutrient and micronutrient." data-term-url="/en/glossary/view/nutrient/7058">nutrient</mark> that has the greatest effect on plant growth in <mark class="term" data-term="aquatic" data-term-def="Related to, located in, or living in or on a body of water. Not terrestrial. Aquatic includes both freshwater and saltwater&hellip;" data-term-url="/en/glossary/view/aquatic/5619">aquatic</mark> <mark class="term" data-term="ecosystem" data-term-def="The complex of a community of organisms and its environment, functioning as a unit." data-term-url="/en/glossary/view/ecosystem/2174">ecosystems</mark>. As Schindler notes in his personal recount of the history of the ELA, the aerial photograph of the two basins shown in Figure 7</p><blockquote class="blockquote"> <p>…had more impact on policy makers than hours of testimony based on scientific data, helping to convince them that controlling phosphorus was the key to controlling eutrophication problems in lakes. (Schindler, 2009)</p> </p></blockquote><p>The reason for phosphorus’s impact is simple. Along with carbon, nitrogen, oxygen, and potassium, phosphorus is a <mark class="term" data-term="macronutrient" data-term-def="Nutrients that are needed in high amounts to sustain life. For example, plants need a high amount of nitrogen, phosphorus, and&hellip;" data-term-url="/en/glossary/view/macronutrient/7075">macronutrient</mark> that determines whether an <mark class="term" data-term="organism" data-term-def="Any connected living system, such as an animal, plant, fungus, or bacterium. Organisms may be composed of a single cell or&hellip;" data-term-url="/en/glossary/view/organism/2171">organism</mark> will grow and survive, or wither and die. Without it, living beings cannot grow, reproduce, move, or do much of anything. But because other macronutrients are readily available, more often than not the <mark class="term" data-term="limiting nutrient" data-term-def="An essential nutrient an organism needs for life that is in the shortest supply in their environment. For example, a tomato&hellip;" data-term-url="/en/glossary/view/limiting+nutrient/7059">limiting nutrient</mark> for plant growth in natural <mark class="term" data-term="ecosystem" data-term-def="The complex of a community of organisms and its environment, functioning as a unit." data-term-url="/en/glossary/view/ecosystem/2174">ecosystems</mark> is phosphorus. This is partly because the largest reservoir of phosphorus is locked up in <mark class="term" data-term="sedimentary" data-term-def="Formed from the deposition or precipitation of sediments. Sedimentary rocks consist of sediments that have been compacted and cemented together." data-term-url="/en/glossary/view/sedimentary/3311">sedimentary</mark> rock and unavailable, and partly because its chemistry in the <mark class="term" data-term="environment" data-term-def="The conditions that surround and affect an organism." data-term-url="/en/glossary/view/environment/8270">environment</mark> limits its availability.</p> <div class="comprehension-checkpoint margin-y-4"> <h6 class="comprehension-checkpoint__header"> <span> <span class="icon icon-question"></span> </span> Comprehension Checkpoint </h6> <form name="cc6651"> <div class="form-entry"> <div class="form-entry__field"> <span class="form-entry__field__label">In the Experimental Lakes Project, which element was found to cause excessive algae growth?</span> <div class="form-entry__option"> <div class="form-entry__option__radio" data-answer="incorrect"> <label> <input id="q1-6651-0-option-a" name="quiz-option-6651" type="radio" value="a combination of nitrogen and carbon" > <span class="option__label"> <span class="screen-reader-only">a.</span> a combination of nitrogen and carbon </span> </label> <span class="quiz__response" id="response-6651-0"> <strong>Incorrect.</strong> </span> </div> <div class="form-entry__option__radio" data-answer="correct"> <label> <input id="q1-6651-1-option-b" name="quiz-option-6651" type="radio" value="phosphorous" > <span class="option__label"> <span class="screen-reader-only">b.</span> phosphorous </span> </label> <span class="quiz__response" id="response-6651-1"> <strong>Correct!</strong> </span> </div> </div> </div> </div> </form> </div> </section> <section id="toc_6"> <h2>Human impacts on the phosphorus cycle</h2><p>Since humans began to walk the Earth, we have interacted with – and influenced – many natural processes, and the phosphorus cycle is no exception. Because phosphates are quite limited in <mark class="term" data-term="soil" data-term-def="The loose top layer of Earth’s surface where plants grow, made up of particles of rocks, minerals, and organic material." data-term-url="/en/glossary/view/soil/8563">soil</mark> naturally, modern agricultural practices frequently involve the application of fertilizers heavy in <mark class="term" data-term="inorganic" data-term-def="Not originating from a living organism; not a compound that contains hydrocarbons." data-term-url="/en/glossary/view/inorganic/8521">inorganic</mark> phosphates. When phosphorus is added to an <mark class="term" data-term="ecosystem" data-term-def="The complex of a community of organisms and its environment, functioning as a unit." data-term-url="/en/glossary/view/ecosystem/2174">ecosystem</mark> through non-natural or excessive means – run-off from farms (both fertilizers and animal excrement), sewerage, or phosphate-containing detergents – the sudden increase in <mark class="term" data-term="nutrient" data-term-def="A chemical substance (e.g., minerals, vitamins, proteins) that is needed by an organism to survive and grow. See also: macronutrient and micronutrient." data-term-url="/en/glossary/view/nutrient/7058">nutrient</mark> availability can have a dramatic effect on plant growth.</p><p>Soil has a <mark class="term" data-term="saturation" data-term-def="the state at which a body or parcel of air has reached its maximum capacity for holding dissolved moisture as water vapor." data-term-url="/en/glossary/view/saturation/12936">saturation</mark> point with respect to how much phosphate it can hold, and plants have a limit as to how fast they can take it up, so the application of too much phosphate results in both <mark class="term" data-term="leaching" data-term-def="Dissolving out by the action of a percolating liquid." data-term-url="/en/glossary/view/leaching/2187">leaching</mark> into the water supply and run-off into lakes, streams, and oceans. Since <mark class="term" data-term="aquatic" data-term-def="Related to, located in, or living in or on a body of water. Not terrestrial. Aquatic includes both freshwater and saltwater&hellip;" data-term-url="/en/glossary/view/aquatic/5619">aquatic</mark> <mark class="term" data-term="ecosystem" data-term-def="The complex of a community of organisms and its environment, functioning as a unit." data-term-url="/en/glossary/view/ecosystem/2174">ecosystems</mark> have very low phosphate <mark class="term" data-term="concentration" data-term-def="The amount of one substance in relation to other components within a given area." data-term-url="/en/glossary/view/concentration/8733">concentrations</mark> naturally, whenever phosphate enters the water column, <mark class="term" data-term="phytoplankton" data-term-def="Microscopic plants, such as algae, that float freely in the water column of an aquatic system (e.g., lake, ocean)." data-term-url="/en/glossary/view/phytoplankton/7074">phytoplankton</mark> like <mark class="term" data-term="algae" data-term-def="(plural form of <b>alga</b>) Mostly aquatic plantlike organisms that range in size from one cell to large multi-celled seaweed and are photosynthetic." data-term-url="/en/glossary/view/algae/8678">algae</mark> quickly consume it.</p><p>As Schindler and his team showed with the ELA, if the influx of phosphate steadily continues for a period of time, the <mark class="term" data-term="algae" data-term-def="(plural form of <b>alga</b>) Mostly aquatic plantlike organisms that range in size from one cell to large multi-celled seaweed and are photosynthetic." data-term-url="/en/glossary/view/algae/8678">algae</mark> and other <mark class="term" data-term="aquatic" data-term-def="Related to, located in, or living in or on a body of water. Not terrestrial. Aquatic includes both freshwater and saltwater&hellip;" data-term-url="/en/glossary/view/aquatic/5619">aquatic</mark> <mark class="term" data-term="phytoplankton" data-term-def="Microscopic plants, such as algae, that float freely in the water column of an aquatic system (e.g., lake, ocean)." data-term-url="/en/glossary/view/phytoplankton/7074">phytoplankton</mark> are able to reproduce so quickly and efficiently that they literally form a mat on the <mark class="term" data-term="surface" data-term-def="The outside or external part; the topside face of something." data-term-url="/en/glossary/view/surface/8275">surface</mark> of the water, blocking out <mark class="term" data-term="light" data-term-def="A form of electromagnetic radiation. Visible light is that associated with stimulating the organs of sight, which for normal human&hellip;" data-term-url="/en/glossary/view/light/1498">light</mark> for other plants and <mark class="term" data-term="organism" data-term-def="Any connected living system, such as an animal, plant, fungus, or bacterium. Organisms may be composed of a single cell or&hellip;" data-term-url="/en/glossary/view/organism/2171">organisms</mark> living below (Figure 8). This reduces the ability of bottom-dwelling plants to <mark class="term" data-term="photosynthesize" data-term-def="The act of performing photosynthesis." data-term-url="/en/glossary/view/photosynthesize/7077">photosynthesize</mark>, reducing the amount of oxygen being released into the water.</p>  <div class="figure"> <figure> <button class="lightbox-button" data-lightbox-src="/img/library/large_images/image_6723.jpg" data-lightbox="image"> <img src="/img/library/modules/mid197/Image/VLObject-6723-140520120510.jpg" alt="Figure 8: Myvatn Lake - a shallow eutrophic lake in northern Iceland." /> </button> <figcaption> <p><strong>Figure 8:</strong> Myvatn Lake - a shallow eutrophic lake in northern Iceland.</p> <span class="credit">image ©Israel Hervas Bengochea/Shutterstock</span> </figcaption> </figure> </div> <p>As the <mark class="term" data-term="algae" data-term-def="(plural form of <b>alga</b>) Mostly aquatic plantlike organisms that range in size from one cell to large multi-celled seaweed and are photosynthetic." data-term-url="/en/glossary/view/algae/8678">algae</mark> die, they fall to the bottom where they are decomposed by <mark class="term" data-term="bacteria" data-term-def="(plural of bacterium) A large group of one-celled organisms that are found almost everywhere." data-term-url="/en/glossary/view/bacteria/8679">bacteria</mark> – a <mark class="term" data-term="process" data-term-def="Method, procedure; series of actions or steps." data-term-url="/en/glossary/view/process/8256">process</mark> that uses a large amount of dissolved oxygen. As this dissolved oxygen is depleted, fish and other <mark class="term" data-term="organism" data-term-def="Any connected living system, such as an animal, plant, fungus, or bacterium. Organisms may be composed of a single cell or&hellip;" data-term-url="/en/glossary/view/organism/2171">organisms</mark> living in the water body slowly suffocate and die.</p><p>Though we have learned better and made many efforts to change, the effects of these practices still linger. The over-application of fertilizers with high <mark class="term" data-term="concentration" data-term-def="The amount of one substance in relation to other components within a given area." data-term-url="/en/glossary/view/concentration/8733">concentrations</mark> of phosphate is still a problem, and bodies of water in places with heavy agricultural communities suffer the greatest. Fortunately, as we learn more about the impacts our actions have on our <mark class="term" data-term="environment" data-term-def="The conditions that surround and affect an organism." data-term-url="/en/glossary/view/environment/8270">environment</mark>, we can consciously make choices that will benefit rather than harm our surroundings.</p><p>The body of <mark class="term" data-term="research" data-term-def="A study or an investigation." data-term-url="/en/glossary/view/research/8257">research</mark> on phosphorus conducted at the Experimental Lakes Area was a seminal contribution to environmental science. While the phosphorous cycle can be simplified, as we did above, to a cycle that includes a geological component and a biological component, the cycle is actually far more detailed than this.</p></section> <footer class="module__main__footer"> <hr class="border-color-dark"> <p class="citation"> <em> Heather MacNeill Falconer, M.A./M.S. “The Phosphorus Cycle” Visionlearning Vol. EAS-3 (1), 2014. </em> </p>  <div class="title-list" id="refs" name="refs"> <p class="h6 title-list__title"> References </p> <ul class="title-list__list"> <li>Cleugh, T. R., & Hauser, B. W. (1971). Results of the initial survey of the Experimental Lakes Area, northwestern Ontario. <em>J. Fish. Res. Board Can., 28</em>, 129-137.</li> <li>Hershey, D. (2003). Misconceptions about Helmont’s Willow Experiment. <em>Plant Science Bulletin</em>, Fall (49.3).</li> <li>Morton, A. G. (1981). <em>History of Botanical Science</em>, Academic Press, London, ISBN 0-12-508480-3, 474.</li> <li>Schindler, D. W., Hecky, R. E., Findlay, D. L., Stainton, M. P., Parker B. R., Paterson, M. J.,...& Kasian, S. E. (2008). Eutrophication of lakes cannot be controlled by reducing nitrogen input: Results of a 37-year whole-ecosystem experiment. <em>PNAS, 105</em>(32), 11254–11258.</li> <li>Schindler, D. W. (1977). Evolution of phosphorus limitation in lakes: Natural mechanisms compensate for deficiencies of nitrogen and carbon in eutrophied lakes. <em>Science, 195</em>, 260–262.</li> <li>Schindler, D. W. (2009). A personal history of the Experimental Lakes Project. <em>Can. J. Fish. Aquatic Sci.</em> (66), 1837-1847.</li> <li>Tindall, J. A., & Krunkel, J. R. (1998). <em>Unsaturated Zone Hydrology for Scientists and Engineers.</em> New York: Pearson.</li> <li>van Helmont, J. B. (1662). <em>Oriatrike or Physick Refined. </em>London: Lodowick Loyd. (translated by John Chandler).</li> <li>von Liebig, Justus. (1840). <em>Organic Chemistry and its Applications to Agriculture and Physiology</em>. London: Taylor and Watson.</li> </ul> </div>  <div class="title-list" name="further"> <p class="h6 title-list__title"> Further Reading </p> <ul class="grid grid--column-2--md grid--column-3--md gap-1"> <li> <a class="no-hover-focus height-100" href="/en/library/Earth-Science/6/The-Nitrogen-Cycle/98"> <article class="flex-row align-items-center flex-column--md align-items-start--md height-100 theme-light padding-2 gap-2"> <div class="width-30 width-auto--md"> <img class="border-radius box-shadow-1" src="/img/library/moduleImages/featured_image_98-23061209065638.jpeg" alt="The Nitrogen Cycle"> </div> <div class="flex-grow-shrink"> <h2 class="h6 font-weight-normal"> The Nitrogen Cycle: <em>Of microbes and men</em> </h2> </div> </article> </a> </li> <li> <a class="no-hover-focus height-100" href="/en/library/Earth-Science/6/The-Carbon-Cycle/95"> <article class="flex-row align-items-center flex-column--md align-items-start--md height-100 theme-light padding-2 gap-2"> <div class="width-30 width-auto--md"> <img class="border-radius box-shadow-1" src="/img/library/moduleImages/featured_image_95-23061209065627.jpg" alt="The Carbon Cycle"> </div> <div class="flex-grow-shrink"> <h2 class="h6 font-weight-normal"> The Carbon Cycle: <em>Geology, biology, and the impact of human activities</em> </h2> </div> </article> </a> </li> </ul> </div> </footer> </div>    </article> </div> </div> </main>   <footer class="position-relative box-shadow-1 font-size-md" id="global-footer"> <h2 class="screen-reader-only">Page Footer</h2> <div class="back-to-top"> <div class="container wide"> <button class="button button--has-icon font-size-sm"> <span class="icon icon-arrow-up"></span> <span class="button__text">Back to top</span> </button> </div> </div> <div class="container wide padding-y-2"> <div class="grid grid--column-2--md grid--column-4--lg gap-4 grid--divider--fill-x"> <nav> <ul class="nav font-weight-bold"> <li> <a href="/en/library" title="Readings & quizzes"> Library </a> </li> <li> <a href="/en/glossary" title="Science terms"> Glossary </a> </li> <li> <a href="/en/classroom" title="Courses & bookmarks"> Classroom </a> </li> </ul> </nav> <nav> <ul class="nav"> <li><a href="/en/about">About</a></li> <li><a href="/en/help">Contact</a></li> <li><a href="/en/about/jobs">Jobs</a></li> <li><a href="/en/help/faq">FAQ</a></li> </ul> </nav> <div> <ul class="nav nav--horizontal margin-bottom-2"> <li> <a class="display-flex" href="https://www.nsf.gov" target="_blank" rel="noopener"> <img src="/images/sponsor-nsf.png" width="60" height="60" alt="US Education Department Logo" /> </a> </li> <li> <a class="display-flex" href="https://www.ed.gov/" target="_blank" rel="noopener"> <img src="/images/sponsor-doe.png" width="60" height="60" alt="US Education Department Logo" /> </a> </li> </ul> <p>Visionlearning is supported by the The National Science Foundation and the U.S. Department of Education. 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