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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. Nutrient Cycling. Energy Flow, Carbon & Oxygen Cycling. J. Corney. The Nitrogen Cycle. Elmhurst.

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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


Nutrient Cycling

Energy Flow, Carbon & Oxygen Cycling

J. Corney


The Nitrogen Cycle

Elmhurst

10% of naturally occurring available nitrogen is generated by lightning.

McGraw-Hill


Nutrient Cycling

Nitrogen Cycling Through an Ecosystem

ECOSYSTEM

N

OTHER

SOURCES

CONSUMERS

N-cmpds

N2

&

NOx

1o 2o 3o

PRODUCERS

DECOMPOSERS

N-cmpds

ATMOSPHERE

SOIL “SINK”

NO3- &NH4+

J. Corney


Carbon vs. Nitrogen Cycles

Carbon cycling is mostly atmosphere based.

Nitrogen cycling is mostly soil based.




Roles of CARBON & NITROGEN:

“Life as a House”

If Carbon comprises the framing and roofing (FORM)…

E Patrol

…then Nitrogen comprises the appliances (FUNCTION).


Key Component of Life’s Molecules

Amino Acids & Proteins

Hemoglobin & Chlorophyll

DNA & RNA

Wikipedia

UDEL

NobelPrize.org


Carbon to Nitrogen (C:N) Ratios

Plants ~ 25:1

Animals

~ 6:1

McGraw-Hill


Nitrogen Is Abundant in Atmosphere

Atmospheric N2

U.S. EPA

…but, N2 as a gas is relatively inert to life


Forms of Nitrogen Available for Life

Nitrogen Free

…but, only plants can absorb Nitrogen

directly from the environment



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.



Fixing Nitrogen…

Atmospheric Nitrogen

Nitrogen -Fixing Bacteria

N2

Nitrogen

Ammonifying Bacteria


Getting to Nitrate…

Nitrifying Bacteria

Nitrosomonas

Nitrobacter


Nutrients Need Water to Move

Nutrient ions are mobile while in a solution of water.

?

DK Clipart

So, how do nutrients move in soil?


Composition of Soil

PhysicalGeography.net


Interstitial Spaces

U of Minnesota


Getting Nutrients to the Plants

U of Georgia

River Partners

USDA-NRCS


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.


Mychorrizhal Relationship Up Close

Plant root

Fungal hyphae

USDA-NRCS

Mycorrhizal structure


2 Types of Mychorrizhal Relationships

Plant a Globe

USDA-NRCS

USDA-NRCS

10% of plant families, mostly woody species (e.g. pine, oak, birch)

80% of plant families, mostly herbaceous species (e.g. grasses, forbs)

Nature


Plant-Fungal Cellular Connection

Image Nature

Oxford Journal

Cold Spring Harbor

RHIZOSPHERE

Area of soil immediately adjacent to plant roots and mychorrizhal structures.


Fungi Help Get Nutrients into Roots

H2O

H2O

NO3-

H2O

NO3-

H2O

H2O

NO3-

NO3-

NH4+

H2O

H2O

NO3-

NO3-

H2O

H2O

NH4+

NH4+

H2O

H2O

M. Harrison




Soil Organisms & Decomposition

Organic Garden

Dr. Jeffrey R. Corney, Managing Director

of the University of Minnesota’s Cedar Creek Ecosystem Science Reserve


Formation of Soil

Brooks-Cole


Soil Layers

Surface Litter

Top Soil

Sub-Soil

Rock

DK Clipart

USDA-NRCS


Cross-Section of Soil

Absolute Science


Soil Ecosystem at Micro-level

USDA-NRCS

Rose & Elliot




Soil Food Chain

Landscape for Life


Soil Food Web

Brooks-Cole


Bacteria, Fungi, & Actinomycetes

USDA-NRCS

USDA-NRCS

USDA-NRCS

USDA-NRCS

Decompose material, mineralize nutrients, fix nitrogen, help aggregate soil particles.



Protozoans

USDA-NRCS

BLM

Mauby

Consume bacteria and fungi, releasing nutrients when excrete wastes.


Nematodes & Springtails

TAMU

USDA-NRCS

Rodale

USDA-NRCS

Consume bacteria, fungi, and protozoans, releasing nutrients when excrete wastes.


Mites, Sowbugs, Millipedes

USDA-NRCS

EcoLibrary

USDA-NRCS

Shred plant litter and consume detritus, increasing ability for microbes to decompose material.


Ants, Beetles, Spiders, Centipedes

Discover Life

USDA-NRCS

Predators that eat other consumers, controlling populations and excreting nutrients.


Earthworms: “Soil Aerators”

Cary Institute

Science Daily

WORM

Mix soil layers, redistributing nutrients throughout soil, and aerate the soil.


Gophers & Ants: “Earth Movers”

Move nutrient poor sub-layers of soil to the surface, helping enrich soil layers.


Soil Organisms By-the-Numbers

1 gram of soil

USDA-NRCS




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

The tips of small plant roots move through the soil with a twisting screw-like motion.  Mature trees can have as many as 5 million active root tips.

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.

Although the soil surface appears solid, air moves freely in and out of it. 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 wheat field can have more than 30,000 miles of roots, greater than the circumference of the Earth.

The wonderful "earthy" smell of newly plowed ground is believed to result from chemicals produced by micro-organisms.  One of these chemicals, called geosmin, is produced by actinomycetes, organisms that have some properties of both bacteria and fungi.

Soil can act as either a sink or a source of greenhouse gases.  An estimated 30 percent of the carbon dioxide, 70 percent of the methane, and 90 percent of the nitrous oxide released to the atmosphere each year pass through the soil.

It takes about 4,000 to 6,000 pounds of crop residue per year to maintain the content of organic matter in a soil.

Modern farming practices that minimize soil disturbance (plowing) and return plant residues to the soil, such as no-till farming and crop rotations, are slowly rebuilding the Nation's stock of soil organic matter.

Of the carbon returned to the soil as plant residue, about 5 to 15 percent become tied up in the bodies of organisms and 60 to 75 percent is respired as carbon dioxide back to the atmosphere. Only 10 to 25 percent is converted to humus in the soil.

“We know more about the movement of celestial bodies than about the soil underfoot.”---Leonardo Da Vinci, circa 1500's

“Every time you take a step in a mature Oregon forest, your foot is being supported on the backs of 16,000 invertebrates held up by an average total of 120,000 legs.” –Dr. Andrew Moldenke, Oregon State University.

Even in agricultural soils, more than a thousand arthropod legs support your every step.

One cup of soil may hold as many bacteria as there are people on Earth.

Bacteria and actinomycetes are exceedingly tiny. Yet, because of their tremendous numbers, they make up half the living biomass in some soils. 

The weight of all the bacteria in one acre of soil can equal the weight of a cow or two. 

Actinomycetes have cells like bacteria, but grow as long filaments like fungi. Like fungi, they help degrade tough materials, but unlike fungi, they prefer high pH (over 7.0). 

A teaspoon of farm soil may contain tens of yards of fungi. The same amount of soil from a coniferous forest may hold tens of miles of fungi.

Nematodes are amazingly diverse. Twenty thousand species have been described, but it is thought that 500,000 species may exist. Five thousand soil species have been described.

Earthworms move from lower strata up to the surface and move organic matter from the soil surface to lower layers. Where earthworms are active, they can turn over the top 6 inches of soil in 10 to 20 years.


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

The tips of small plant roots move through the soil with a twisting screw-like motion.  Mature trees can have as many as 5 million active root tips.

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.

Although the soil surface appears solid, air moves freely in and out of it. 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 wheat field can have more than 30,000 miles of roots, greater than the circumference of the Earth.

The wonderful "earthy" smell of newly plowed ground is believed to result from chemicals produced by micro-organisms.  One of these chemicals, called geosmin, is produced by actinomycetes, organisms that have some properties of both bacteria and fungi.

Soil can act as either a sink or a source of greenhouse gases.  An estimated 30 percent of the carbon dioxide, 70 percent of the methane, and 90 percent of the nitrous oxide released to the atmosphere each year pass through the soil.

It takes about 4,000 to 6,000 pounds of crop residue per year to maintain the content of organic matter in a soil.

Modern farming practices that minimize soil disturbance (plowing) and return plant residues to the soil, such as no-till farming and crop rotations, are slowly rebuilding the Nation's stock of soil organic matter.

Of the carbon returned to the soil as plant residue, about 5 to 15 percent become tied up in the bodies of organisms and 60 to 75 percent is respired as carbon dioxide back to the atmosphere. Only 10 to 25 percent is converted to humus in the soil.

“We know more about the movement of celestial bodies than about the soil underfoot.”---Leonardo Da Vinci, circa 1500's

“Every time you take a step in a mature Oregon forest, your foot is being supported on the backs of 16,000 invertebrates held up by an average total of 120,000 legs.” –Dr. Andrew Moldenke, Oregon State University.

Even in agricultural soils, more than a thousand arthropod legs support your every step.

One cup of soil may hold as many bacteria as there are people on Earth.

Bacteria and actinomycetes are exceedingly tiny. Yet, because of their tremendous numbers, they make up half the living biomass in some soils. 

The weight of all the bacteria in one acre of soil can equal the weight of a cow or two. 

Actinomycetes have cells like bacteria, but grow as long filaments like fungi. Like fungi, they help degrade tough materials, but unlike fungi, they prefer high pH (over 7.0). 

A teaspoon of farm soil may contain tens of yards of fungi. The same amount of soil from a coniferous forest may hold tens of miles of fungi.

Nematodes are amazingly diverse. Twenty thousand species have been described, but it is thought that 500,000 species may exist. Five thousand soil species have been described.

Earthworms move from lower strata up to the surface and move organic matter from the soil surface to lower layers. Where earthworms are active, they can turn over the top 6 inches of soil in 10 to 20 years.


Sustainability Issues

THE CONCERN:

Nitrogen Deposition & Eutrophication

“Too Much of

a Good Thing”


Sustainability Issues

Global Sources of Nitrogen Today

Scientific American

Vitousek & Matson


Sustainability Issues

Haber-Bosch “Synthetic” Nitrogen

Fertilizer 101

Fritz Haber Carl Bosch

Menlo School

Invented process in early 1900s


Sustainability Issues

Nitrogen Use, Agricultural Revolution,

and Human Population Growth

Tilman


Sustainability Issues

Soil Nitrogen Runoff from Fertilizer


Sustainability Issues

Atmospheric Nitrogen Deposition


Sustainability Issues

Excessive Nitrogen

in Mississippi Watershed

USGS


Sustainability Issues

Process of Eutrophication


Sustainability Issues

Eutrophication of Coastal Gulf Waters


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]


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