Soil Labs

3/29/2020 Soil Nitrogen and Sulfur (Chapter 13) Notes - AGRI1050R50: Introduction to Soil Science (2020S)

https://gotoclass.tnecampus.org/d2l/le/content/8094442/viewContent/60403422/View 1/14

Soil Nitrogen and Sulfur (Chapter 13) Notes

Soil Nitrogen and Sulfur (Chapter 13) Notes

Did you know .... Did you know that nitrogen is commonly the most limiting nutrient in agronomic settings? Chapter 11 begins our journey through the major plant limiting nutrients and their cycles in soil discussing why nitrogen is most limiting, how nitrogen cycles in soil, and then reviewing similar information for sulfur.

Lecture content notes are accompanied by videos listed below the notes in each submodule (e.g. Soil Nitrogen and Sulfur (Chapter 14) Videos A though E). Print or download lecture notes then view videos in succession alongside lecture content and add additional notes from each video. The start of each video is noted in parenthesis (e.g. Content for Video A) within each lecture note set and contains lecture content through the note for the next video (e.g. Content for Video B).

Figures and tables unless specifically referenced are from the course text, Nature and Property of Soils, 14th Edition, Brady and Weil.

Content Video A

Soil Nitrogen

Nitrogen Generally most limiting macronutrients

Yellow, Chlorotic Tissue

AGRI1050R50: Introduction to Soil Science (2020S) LH

3/29/2020 Soil Nitrogen and Sulfur (Chapter 13) Notes - AGRI1050R50: Introduction to Soil Science (2020S)

https://gotoclass.tnecampus.org/d2l/le/content/8094442/viewContent/60403422/View 2/14

Necessary Requirement for High Productivity

Major Plant Component - Microbial too!

Amino Acids

Nucleic Acids

Proteins

Enzymes

Chlorophyll

Plants utilize cation, anion, and organic forms:

Ammonium – NH4+

Nitrate - NO3- - most plants prefer

Low Molecular Weight Organics – proteins and amino acids

Nitrogen in Soil Atmosphere 78% N2 gas

N≡N – Triple Bond, Inert

Transform into Reactive Species

Lightening

Microbial Fixation

NO3-, NH4+, Organics

Soil N – generally low amounts plant available

SOM – degradation makes available

Fixed in minerals

Inorganics – Very Soluble – Easy to Loose!

Nitrogen Cycle

Nitrogen Cycle

3/29/2020 Soil Nitrogen and Sulfur (Chapter 13) Notes - AGRI1050R50: Introduction to Soil Science (2020S)

https://gotoclass.tnecampus.org/d2l/le/content/8094442/viewContent/60403422/View 3/14

Soil and Environmental Quality, 2nd Edition, Pierzynski, et al.

Components of the Nitrogen Cycle Inputs

3/29/2020 Soil Nitrogen and Sulfur (Chapter 13) Notes - AGRI1050R50: Introduction to Soil Science (2020S)

https://gotoclass.tnecampus.org/d2l/le/content/8094442/viewContent/60403422/View 4/14

Inputs

N Fixation

Atmospheric Deposition

Commercial Fertilizers

Transformations

Mineralization

Immobilization

Nitrification

Denitrification

Losses

Denitrification

Leaching

Erosion

Ammonia Volatilization

Fixation by Clays

Plant Uptake

Content Video B

Nitrogen Inputs Lightening

Breaks apart triple bonds

Gaseous forms of N, then Nitrates

Come back to surface: rain, snow, dust, etc.

Atmospheric Nitrogen Deposition

Industry and CAFO

SOX –NOX gasses

Problem for forests and aquatic life

Industrial Fixation of Nitrogen Gas to Ammonia

Extreme Pressure and Heat

Haber-Bosh – Germans – World War I

Thought to be one of the greatest developments of the 20th century

Move from organic N to synthetic N – Huge boost productivity

Inputs: Biological Nitrogen Fixation Conversion of Atmospheric N2 into Organic N

Symbiotic

3/29/2020 Soil Nitrogen and Sulfur (Chapter 13) Notes - AGRI1050R50: Introduction to Soil Science (2020S)

https://gotoclass.tnecampus.org/d2l/le/content/8094442/viewContent/60403422/View 5/14

Symbiotic

Legumes – Bacteria

Non-Legumes – Actinomycetes

Independent – Cyanobacteria and Heterotrophic Bacteria

Catalyst – Nitrogenase Enzyme

Requires LOTS of Energy – Plant association plus

Destroyed by oxygen – Protect in nodule – Leghemoglobin

Soybean Root Nodules – Bradyrhizobium

3/29/2020 Soil Nitrogen and Sulfur (Chapter 13) Notes - AGRI1050R50: Introduction to Soil Science (2020S)

https://gotoclass.tnecampus.org/d2l/le/content/8094442/viewContent/60403422/View 6/14

https://www.pioneer.com/home/site/about/template.CONTENT/guid.F3A614D9-9AF1-AC5A-B4FC- E064EBF7BB38/

http://www.agweb.com/article/bacteria_give_beans_a_boost/

Nitrogen Cycle

3/29/2020 Soil Nitrogen and Sulfur (Chapter 13) Notes - AGRI1050R50: Introduction to Soil Science (2020S)

https://gotoclass.tnecampus.org/d2l/le/content/8094442/viewContent/60403422/View 7/14

Content Video C

Mineralization and Immobilization Mineralization – Conversion of Organic to Inorganic Forms

Immobilization – Conversion of Inorganic to Organic Forms

Transformations: Mineralization Conversion of Organic N to Inorganic N

Organic N – “Bioparticles” and SOM

Proteins, Amino Acids, Ammine (Organic w/ NH2)

Indigenous N sources (SOM), crop residues, or manure

Microbial community yield energy w/ change of oxidation state N

N for growth and provide plant available N

SOM ~5% N – 1 to 3 % SOM degraded/yr

Soil with 2% SOM – 2,000 kg N/ha (1780 lbs/acre)

2% Mineralized/year – 40 kg N/ha (36 lbs/acre) <Generous>

Much lower than high value crop needs – Add commercial N fertilizer

Transformations: Immobilization Conversion of Inorganic N to Organic N

Opposite of Mineralization

3/29/2020 Soil Nitrogen and Sulfur (Chapter 13) Notes - AGRI1050R50: Introduction to Soil Science (2020S)

https://gotoclass.tnecampus.org/d2l/le/content/8094442/viewContent/60403422/View 8/14

Microbial Assimilation

Microbial community then goes to work on organic C

Mineralization – Immobilization Simultaneous

Nutritional Balance and Soil Conditions Dictate

Transformations: C:N Ratios C:N Ratio > 30 – Net Immobilization

Microbes using N for own use; not adding to system

C:N Ratio < 20 – Net Mineralization

Microbes able to use C and N, cycle, build SOM, add N back to system

Implications

Composing with High C:N

Mulches

Wheat Straw Degradation

Transformations: Nitrification Nitrification: Bacterial Oxidation of NH4+ to NO3-

Conditions right and bacteria available – RAPID – Chemoautotrophs

Warm, Moist soil

Ammonium

Oxygen

Nitrite is toxic to plants

Reaction same – No matter what N source - mineralization, manure, commercial fertilizer

Source of acidity – H+

Content Video D

Transformation/Loss: Denitrification Denitrification: Reduction of NO3- to Gaseous Forms N

Anaerobic Conditions

Wet conditions – Saturated soils after big rain can have anaerobic zones in hours

Microsites in colloids

Heterotrophic – Facultative Anaerobes

NO3- Terminal Electron Acceptor

Many soil genera: Pseudomonas, Bacillus, Micrococcus, etc.

Organic C for the microbial community

3/29/2020 Soil Nitrogen and Sulfur (Chapter 13) Notes - AGRI1050R50: Introduction to Soil Science (2020S)

https://gotoclass.tnecampus.org/d2l/le/content/8094442/viewContent/60403422/View 9/14

Organic C for the microbial community

Warm/Moist temperatures

Significant – Important LOSS of N

Con: GHC Source Pro: Wetlands, Decrease Nitrate

Loss: Ammonia Volatilization Ammonia Volatilization – Gaseous Loss NH3↑

High pH – Alkaline soils – Force equation to the right – Greater Loss

Urea - N Fertilizer – NH2-CO-NH2 – Surface Applied

Warm and Moist – Urea absorbs moisture – Forms Ammonia Gas – LOSS

Problematic only for ~2 week period after application

Urea levels high in animal manure – Manage – Can inject/incorporate

Management Issue

Loss: Nitrate via Leaching, Runoff, Erosion Nitrate - NO3- - Anion

Mechanisms of Loss

Plant uptake (Ideal)

Leaches thru profile with water (Organic N too)

Transported in runoff water (NH4+ too)

Transported in soil with erosion (NH4+ too)

Environmental and Health Issue

Eutrophication – Excess nutrients in water

Drinking water - Nitrate metabolism products harmful

Chesapeake Bay

Dead Zone in the Gulf

N Loss: Fixation in Clays NH4+ - Cation

Attracted to negative charges in soil colloids

Fixation

Similar in size to K

2:1 Expanding clays – Vermiculite

Fixed in Interlayers – Unavailable

More Clay with depth – More fixation

Content Video E

Nitrogen Cycle

3/29/2020 Soil Nitrogen and Sulfur (Chapter 13) Notes - AGRI1050R50: Introduction to Soil Science (2020S)

https://gotoclass.tnecampus.org/d2l/le/content/8094442/viewContent/60403422/View 10/14

Soil and Environmental Quality, 2nd Edition, Pierzynski, et al.

Management of N Commercial Fertilizer Industry

“Insurance Fertilizer”

Paradigm Shift

N Fertilizer Cost HIGH

Severe Environmental Ramifications

Precision Agriculture

Urban Issues

Golf Courses

Small Yards

Nitrogen Cycle

3/29/2020 Soil Nitrogen and Sulfur (Chapter 13) Notes - AGRI1050R50: Introduction to Soil Science (2020S)

https://gotoclass.tnecampus.org/d2l/le/content/8094442/viewContent/60403422/View 11/14

Nitrogen Cycle 4 Major Transformations

Mineralization / Immobilization

Nitrification

Denitrification

Nitrogen (N2) Fixation

What is happening to the N itself?

Why is it happening?

When does it occur?

How does it occur?

Where/when might you expect this to occur?

And who is doing the transformation?

Content Video F

Soil Sulfur

https://www.pioneer.com/home/site/us/agronomy/library/template.CONTENT/guid.7786411D-9BC0-C084-8A66- CC7BE3A9C8E9

Sulfur Secondary Macronutrient

3/29/2020 Soil Nitrogen and Sulfur (Chapter 13) Notes - AGRI1050R50: Introduction to Soil Science (2020S)

https://gotoclass.tnecampus.org/d2l/le/content/8094442/viewContent/60403422/View 12/14

Decrease in sulfur containing compounds – fertilizers, pesticides, emissions, etc.

Somewhat limited in agronomic soils

Essential nutrient – biological systems

Amino Acids

Vitamins

Enzymes

Hormones

Cabbage and onions – Aromatics w/ Sulfur – Smell and Taste

Sulfur in Soil Sulfur Availability:

Majority in SOM

Parent Materials – Weather – Gypsum

Adsorption Sulfur Dioxide Gas – Atmosphere

Plant Uptake:

Sulfate – SO4-

Sorption – Rain/Dust – Various Forms - H2S, SO2, H2SO4

Sulfur Cycle – Similar to N

Plant Sulfur Uptake

Sulfur Cycle

3/29/2020 Soil Nitrogen and Sulfur (Chapter 13) Notes - AGRI1050R50: Introduction to Soil Science (2020S)

https://gotoclass.tnecampus.org/d2l/le/content/8094442/viewContent/60403422/View 13/14

Soil and Environmental Quality, 2nd Edition, Pierzynski, et al.

Acid Mine Drainage

3/29/2020 Soil Nitrogen and Sulfur (Chapter 13) Notes - AGRI1050R50: Introduction to Soil Science (2020S)

https://gotoclass.tnecampus.org/d2l/le/content/8094442/viewContent/60403422/View 14/14

Reflect in ePortfolio Download Print

Acid Mine Drainage Appalachian Coal Mining – Pyrite (FeS2) Overburden

Oxygenation of metal sulfites (Pyrite and others) yields tremendous amounts of acid

Thiobacillus sp. mediate process

Mining companies tasked with remediation:

Rock overburden dumped on top of the ground

Build soil structure – add organic materials

Remediate acidity – Liming materials

Re-vegetate

West Virginia - Acid Mine Drainage

http://www.dep.wv.gov/WWE/getinvolved/sos/Pages/AMD.aspx

Review Sulfur Why is sulfur an important nutrient?

Task: View this topic

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