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NUTRIENT CYCLING NITROGEN CYCLING THROUGH ECOSYSTEMS D. Kindersley Nitrogen Free Dr. Jeffrey R. Corney, Managing Director of the University of Minnesota’s Cedar Creek Ecosystem Science Reserve N UTRIENT CYCLING ENERGY FLOW Energy Flow, Carbon & Oxygen Cycling J. Corney NUTRIENT CYCLING Elmhurst The Nitrogen Cycle McGraw-Hill 10% of naturally occurring available nitrogen is generated by lightning. N UTRIENT CYCLING ENERGY FLOW Nitrogen Cycling Through an Ecosystem ECOSYSTEM N OTHER SOURCES CONSUMERS N-cmpds N2 1o 2o 3o PRODUCERS & NOx N-cmpds SOIL “SINK” ATMOSPHERE DECOMPOSERS NO3- & NH4+ J. Corney NUTRIENT CYCLING Carbon vs. Nitrogen Cycles Carbon cycling is mostly atmosphere based. Nitrogen cycling is mostly soil based. NUTRIENT CYCLING Carbon & Nitrogen Cycles Are Linked U.S. Dept of Energy NUTRIENT CYCLING In the “Top Four” Elements for Life Pearson ASU NUTRIENT CYCLING Roles of CARBON & NITROGEN: “Life as a House” E Patrol If Carbon comprises the framing and roofing (FORM)… …then Nitrogen comprises the appliances (FUNCTION). NUTRIENT CYCLING Key Component of Life’s Molecules Amino Acids & Proteins Hemoglobin & Chlorophyll DNA & RNA UDEL Wikipedia NUTRIENT CYCLING Carbon to Nitrogen (C:N) Ratios Plants ~ 25:1 Animals ~ 6:1 McGraw-Hill NUTRIENT CYCLING Nitrogen Is Abundant in Atmosphere Atmospheric N2 U.S. EPA …but, N2 as a gas is relatively inert to life NUTRIENT CYCLING Forms of Nitrogen Available for Life Nitrogen Free …but, only plants can absorb Nitrogen directly from the environment NUTRIENT CYCLING The Nitrogen Cycle NUTRIENT CYCLING Organic vs. Inorganic Nitrogen Organisms consume other organisms and excrete inorganic wastes. Organic (immobile) nutrients are stored in soil organisms and organic matter. Inorganic (mineral) nutrients are usable by plants, and are mobile in soil. USDA-NRCS Organisms take up and retain nutrients as they grow. NUTRIENT CYCLING Nitrogen Cycle (zoomed in) NUTRIENT CYCLING Fixing Nitrogen… Nitrogen -Fixing Bacteria Atmospheric Nitrogen N2 Nitrogen Ammonifying Bacteria NUTRIENT CYCLING Getting to Nitrate… Nitrifying Bacteria Nitrosomonas Nitrobacter NUTRIENT CYCLING Nutrients Need Water to Move ? DK Clipart Nutrient ions are mobile while in a solution of water. So, how do nutrients move in soil? NUTRIENT CYCLING Composition of Soil NUTRIENT CYCLING U of Minnesota Interstitial Spaces NUTRIENT CYCLING Getting Nutrients to the Plants U of Georgia USDA-NRCS NUTRIENT CYCLING Mychorrizhae: Plants & Fungi Together 90% of plant families have mychorrizhal associations. Agro-Genesis A symbiotic, mutualistic association between a fungus and the roots of plants. NUTRIENT CYCLING Mychorrizhal Relationship Up Close Plant root Fungal hyphae USDA-NRCS Mycorrhizal structure NUTRIENT CYCLING 10% of plant families, mostly woody species (e.g. pine, oak, birch) USDA-NRCS USDA-NRCS Plant a Globe 2 Types of Mychorrizhal Relationships Nature 80% of plant families, mostly herbaceous species (e.g. grasses, forbs) NUTRIENT CYCLING RHIZOSPHERE Area of soil immediately adjacent to plant roots and mychorrizhal structures. Oxford Journal Cold Spring Harbor Image Nature Plant-Fungal Cellular Connection NUTRIENT CYCLING Fungi Help Get Nutrients into Roots H2O H2O NO3- NO3H2O H2O H2O NO3H 2O NO3NH4+ NO3- NO3- H 2O NH4+ M. Harrison NH4+ H2 O H 2O H2O H2O NUTRIENT CYCLING Tutor Vista Nutrients Move from Roots to Shoots Helicon J. Corney NUTRIENT CYCLING NUTRIENT CYCLING SOIL ORGANISMS & DECOMPOSITION Dr. Jeffrey R. Corney, Managing Director of the University of Minnesota’s Cedar Creek Ecosystem Science Reserve NUTRIENT CYCLING Formation of Soil Brooks-Cole NUTRIENT CYCLING Soil Layers Surface Litter Top Soil Rock DK Clipart Sub-Soil NUTRIENT CYCLING Cross-Section of Soil NUTRIENT CYCLING USDA-NRCS Soil Ecosystem at Micro-level Rose & Elliot NUTRIENT CYCLING McGraw-Hill Process of Decomposition of Animals NUTRIENT CYCLING Brooks-Cole Process of Decomposition of Plants NUTRIENT CYCLING Soil Food Chain Landscape for Life NUTRIENT CYCLING Soil Food Web Brooks-Cole NUTRIENT CYCLING USDA-NRCS USDA-NRCS USDA-NRCS USDA-NRCS Bacteria, Fungi, & Actinomycetes Decompose material, mineralize nutrients, fix nitrogen, help aggregate soil particles. NUTRIENT CYCLING Annual Microbial Activity by Season USDA-NRCS NUTRIENT CYCLING Mauby BLM USDA-NRCS Protozoans Consume bacteria and fungi, releasing nutrients when excrete wastes. NUTRIENT CYCLING Rodale USDA-NRCS TAMU USDA-NRCS Nematodes & Springtails Consume bacteria, fungi, and protozoans, releasing nutrients when excrete wastes. NUTRIENT CYCLING Shred plant litter and consume detritus, increasing ability for microbes to decompose material. EcoLibrary USDA-NRCS USDA-NRCS Mites, Sowbugs, Millipedes NUTRIENT CYCLING USDA-NRCS Discover Life Ants, Beetles, Spiders, Centipedes Predators that eat other consumers, controlling populations and excreting nutrients. NUTRIENT CYCLING Cary Institute WORM Science Daily Earthworms: “Soil Aerators” Mix soil layers, redistributing nutrients throughout soil, and aerate the soil. NUTRIENT CYCLING Gophers & Ants: “Earth Movers” Move nutrient poor sub-layers of soil to the surface, helping enrich soil layers. NUTRIENT CYCLING Soil Organisms By-the-Numbers 1 gram of soil USDA-NRCS NUTRIENT CYCLING Soil Organisms By Type of Ecosystem USDA-NRCS NUTRIENT CYCLING Soil Biodiversity by Ecosystem USDA-NRCS NUTRIENT CYCLING Fun Facts About Soil A single spade full of rich garden soil contains more species of organisms than can be found above ground in the entire Amazon rain forest. One cup of soil may hold as many bacteria as there are people on Earth. The weight of all the bacteria in one acre of soil can equal the weight of a cow. A teaspoon of soil from a coniferous forest may hold tens of miles of fungi. The air in the upper 8 inches of a well-drained soil is completely renewed about every hour. The plants growing in a 2-acre field can have more than 30,000 miles of roots, greater than the circumference of the Earth. Mature trees can have as many as 5 million active root tips. SOURCE: USDA-NRCS NUTRIENT CYCLING More Fun Facts About Soil Twenty thousand species of nematodes have been described, but it is thought that 500,000 species may exist. Every time you take a step in a mature forest, your foot is being supported on the backs of 16,000 invertebrates held up by an average total of 120,000 legs. There is an estimated one quadrillion individual ants on the planet; that’s approximately 150,000 ants for every one human being. Where earthworms are active, they can turn over the entire top 6 inches of soil in 10 to 20 years. Pocket gopher mounds can cover as much as 25% of a grassland’s ground surface, depositing on average 20 tons of soil per acre per year. SOURCE: USDA-NRCS N UTRIENT CYCLING SUSTAINABILITY ISSUES THE CONCERN: Nitrogen Deposition & Eutrophication “Too Much of a Good Thing” N UTRIENT CYCLING SUSTAINABILITY ISSUES Global Sources of Nitrogen Today Vitousek & Matson N UTRIENT CYCLING SUSTAINABILITY ISSUES Haber-Bosch “Synthetic” Nitrogen Fritz Haber Carl Bosch Invented process in early 1900s Menlo School Fertilizer 101 N UTRIENT CYCLING SUSTAINABILITY ISSUES Nitrogen Use, Agricultural Revolution, and Human Population Growth Tilman N UTRIENT CYCLING SUSTAINABILITY ISSUES Soil Nitrogen Runoff from Fertilizer N UTRIENT CYCLING SUSTAINABILITY ISSUES Atmospheric Nitrogen Deposition N UTRIENT CYCLING SUSTAINABILITY ISSUES Excessive Nitrogen in Mississippi Watershed USGS N UTRIENT CYCLING SUSTAINABILITY ISSUES Process of Eutrophication N UTRIENT CYCLING SUSTAINABILITY ISSUES Eutrophication of Coastal Gulf Waters NUTRIENT CYCLING Dr. Jeffrey R. Corney, Managing Director University of Minnesota Cedar Creek Ecosystem Science Reserve 2660 Fawn Lake Dr NE East Bethel, MN 55005 (763) 434-5131 www.cedarcreek.umn.edu [email protected]