Biogeochemistry of Wetlands

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Institute of Food and Agricultural Sciences (IFAS) Biogeochemistry of Wetlands

Soil and Water Science Department University of Florida Instructor : Patrick

WBL Inglett 1 1 Introduction Nitrogen N Forms, Distribution, Importance Basic

1 Institute of Food and Agricultural Sciences (IFAS) Biogeochemistry of Wetlands Si Science and da Applications NITROGEN Wetland Biogeochemistry Laboratory Soil and Water Science Department University of Florida Instructor : Patrick Inglett pinglett@ufl.edu 6/22/2008 P.W. WBL Inglett 1 1 Introduction Nitrogen N Forms, Distribution, Importance Basic processes of N Cycles Examples of current research Examples of applications Key points learned 6/22/2008 P.W. Inglett 2 1

2 Nitrogen Learning Objectives Identify the forms of N in wetlands Understand the importance of N in wetlands/global processes Define the major N processes/transformations Understand the importance of microbial activity in N transformations Understand the potential regulators of N processes See the application of N cycle principles to understanding natural and manmade ecosystems 6/22/2008 P.W. Inglett 3 Nitrogen Cycling Plant biomass N N 2 N 2 O (g) Nitrogen Fixation N 2 Litterfall NH 3 Volatilization NO 3 Nitrification NH Organic N Mineralization. Water Column NO Plant 3 [ ] s uptake Denitrification N 2, N 2 O (g) Organic N Peat accretion Microbial Biomass N [ ] s AEROBIC ANAEROBIC Adsorbed 6/22/2008 P.W. Inglett 2

3 Forms of Nitrogen Organic Nitrogen Inorganic Nitrogen Proteins Ammonium ( ) Amino Sugars Nitrate N (NO 3 ) Nucleic Acids Nitrite N (NO 2 ) Urea Nitrous oxide (N 2 O) Dinitrogen (N 2 ) 6/22/2008 P.W. Inglett 5 N Transformations Solid Phase: Particulate N Bound: NH NO 3 NO 2 Gaseous Phase: N 2 N 2 O DIN Aqueous Phase: NO 3 NO 2 DON Particulate N 6/22/2008 P.W. Inglett 6 3

4 Reservoirs of Nitrogen Lithosphere 163,600 x g Atmosphere 3,860 x g Hydrosphere 23 x g Biosphere 0.28 x g 6/22/2008 P.W. Inglett 7 Forms of Nitrogen Total Soil N Organic Inorganic Protein Amino sugars Heterocyclic N Clayfixed 6/22/2008 P.W. Inglett 8

5 Nitrogen Transformations 1. Ammonification/Mineralization 2. Immobilization 3. Nitrification. Denitrification 5. Dissimilatory nitrate reduction to ammonia (DNRA) 6. Nitrogen fixation 7. Ammonia volatilization 6/22/2008 P.W. Inglett 9 Transformation of N Species Organic N 2 1 NH 7 3 NH 3 5 8e 3 NO 3 3 NH 2e 2 OH e NO 2e 2 2 e N 2 O 2e 6 3e N 2 1e Oxidation Number 5 6/22/2008 P.W. Inglett 10 5

6 Nitrogen Cycle Plant/Algae OrgN NO 3 NFixers Nitrifiersifi Denitrifiers ifi Microbial Biomass N 2 N 2 /N 2 O 6/22/2008 P.W. Inglett 11 Productivity 6/22/2008 P.W. Inglett 12 6

Porewater (DIN, DON) Exchangeable N Clay fixed N

7 Greenhouse Gas Emissions 6/22/2008 P.W. Inglett 13 Nitrogen Budget Biological N 2 fixation Dry and wet deposition Nonpoint sources Wastewaters Plant biomass Microbial biomass Soil organic N Porewater (DIN, DON) Exchangeable N Clay fixed N Volatilization Outflow Gaseous losses Plant harvest 6/22/2008 P.W. Inglett 1 7

8 1985 Ammonium Ion Wet Deposition /22/2008 P.W. Inglett Nitrate Ion Wet Deposition /22/2008 P.W. Inglett 16 8

Nitrification NH Organic N Mineralization.

9 1985 Inorganic N Wet Deposition /22/2008 P.W. Inglett 17 Biological Nitrogen Fixation Plant biomass N N 2 N 2 O (g) Nitrogen Fixation N 2 Litterfall NH 3 Volatilization NO 3 Nitrification NH Organic N Mineralization. Water Column NO Plant 3 [ ] s uptake Denitrification N 2, N 2 O (g) Organic N Peat accretion Microbial Biomass N [ ] s AEROBIC ANAEROBIC Adsorbed 6/22/2008 P.W. Inglett 18 9

Nitrogen Fixation Type of fixation N 2 fixed (10 12 g yr 1 ) Nonbiological Industrial about 50 Combustion about 20 Lightning about 10 Total about 80 Biological Agricultural land about 90

10 Nitrogen Fixation Type of fixation N 2 fixed (10 12 g yr 1 ) Nonbiological Industrial about 50 Combustion about 20 Lightning about 10 Total about 80 Biological Agricultural land about 90 Forest and nonagricultural land about 50 Sea about 35 Total about 175 6/22/2008 P.W. Inglett 19 Biological N 2 Fixation N N 8H 8e 16ATP 2NH 3 H 2 16ADP 16P i Nitrogenase 6/22/2008 P.W. Inglett 20 10

Biological N 2 Fixation Prokaryotes Aerobic Azotobacter Beijerinckia Klebsiella Cyanobacteria Anaerobic Clostridium Desulfovibrio Cyanobacteria Associated w/ Plants Rhizobium Frankia Azospirillum

11 Biological N 2 Fixation Prokaryotes Aerobic Azotobacter Beijerinckia Klebsiella Cyanobacteria Anaerobic Clostridium Desulfovibrio Cyanobacteria Associated w/ Plants Rhizobium Frankia Azospirillum 6/22/2008 P.W. Inglett 21 Biological N 2 Fixation Heterocysts (cyanobacteria) Leghaemoglobin (rhizobium) Exopolysaccharides Temporal isolation images/book_/chapter_2/253.jpg 6/22/2008 P.W. Inglett 22 11

12 Temporal Isolation Nitrogenase activity Heterocystous Nonheterocystous 12:00 2:00 12:00 Time (h) 6/22/2008 P.W. Inglett 23 Biological N 2 Fixation Regulators? Light Concentration of Oxygen Growth limitation Macro nutrients (C, P) Cofactors (Fe, Mo) Inc. Growth Inc. N Demand Species shift Inc. N 2 Fixation 6/22/2008 P.W. Inglett 2 12

13 Nitrogen Mineralization Plant biomass N N 2 N 2 O (g) Nitrogen Fixation N 2 Litterfall NH 3 Volatilization NO 3 Nitrification NH Organic N Mineralization. Water Column NO Plant 3 [ ] s uptake Denitrification N 2, N 2 O (g) Organic N Peat accretion Microbial Biomass N [ ] s AEROBIC ANAEROBIC Adsorbed 6/22/2008 P.W. Inglett 25 Organic Nitrogen Proteins Amino acids (3050% of total organic N) Nucleic Acids 25 % of total organic N Amino Sugars 313% of total organic N Urea 6/22/2008 P.W. Inglett 26 13

14 Protein Decomposition Proteins Peptides Amino acids Proteases Arg Pro Ala Peptidases Arg Pro Ala Asp Phe Asp Lys Phe Pro Lys Pro 6/22/2008 P.W. Inglett 27 H H R 1 O N C COH H H H R 2 O N C COH H H H R 3 O N C COH H 2H 2 O H H R 1 O R 2 O R 3 N C C N C C N C C OH H H H H H O Peptide Bonds 6/22/2008 P.W. Inglett 28 1

15 H H R 1 O N C COH H H H R 2 O N C COH H H H R 3 O N C COH H 2H 2 O H H R 1 O R 2 O R 3 N C C N C C N C C OH H H H H H O Peptide Bonds 6/22/2008 P.W. Inglett 29 Detrital Matter Complex Polymers Cellulose, Hemicellulose, Proteins, Lipids, Waxes, Lignin Enzyme Hydrolysis Monomers Sugars, Amino Acids Fatty Acids Leaching Uptake Bacterial Cell Electron Acceptors: O 2, NO 3, Mn, Fe 3, SO 2, CO 2 Amino acids Products: CO 2, H 2 O,, Mn 2, Fe 2,S 2,CH Energy ATP 6/22/2008 P.W. Inglett 30 15

16 Urea Decomposition NH 2 Urease C = O H 2 O CO 2 2NH 3 NH 2 6/22/2008 P.W. Inglett 31 Urea Decomposition Urease activity ( 1 C Tracer) [Thorén (2007)] 6/22/2008 P.W. Inglett 32 16

17 Organic N Ammonification [Mineralization] Ammonium N [Breakdown of Organic Matter] Inorganic N ( N and NO 3 N) Immobilization [Buildup of Organic Matter] Organic N 6/22/2008 P.W. Inglett 33 Ammonification/NMineralization Organic N R HOOC C NH 2 H Ammonium Inorganic N NO 3 NImmobilization Organic N R HOOC C NH 2 H 6/22/2008 P.W. Inglett 3 17

18 Microbial Biomass C & N [Everglades WCA2A] Mic crobial biomass C (g C kg 1 ) y = 10.7 x 2.2 R 2 = Microbial biomass N (g N kg 1 ) White and Reddy, /22/2008 P.W. Inglett 35 Decomposition Microbial Biomass C/N ratio = 10 Efficiency i of carbon assimilation il Aerobic = 2060% Anaerobic = 10% Plant Detritus [100 units] 0% carbon (dry weight basis) = 0 units C Amount of C assimilated during decomposition Aerobic = 16 units [0% efficiency] Anaerobic = units [10% efficiency] 6/22/2008 P.W. Inglett 36 18

19 Carbon/Nitrogen Ratio Nitrogen Demand? Microbial Biomass C/N ratio = 10 Aerobic = 1.6 units Anaerobic = 0. units Critical Plant Detritus Nitrogen? Aerobic = 1.6 % Anaerobic = 0.% Critical Carbon/Nitrogen Ratio? Aerobic = [0% C]/[1.6% N] = 25 Anaerobic = [0% C]/[0.% N] = 100 6/22/2008 P.W. Inglett 37 Carbon/Nitrogen Ratio Mineralization [M] vs. Immobilization [I] Aerobic I > M = C/N ratio > 25 M > I = C/N ratio < 25 Anaerobic I > M = C/N ratio > 100 M > I = C/N ratio < 100 6/22/2008 P.W. Inglett 38 19

20 N Mineralization/Immobilization [Aerobic] In norganic N Rele ease C/N = 15 C/N = 35 C/N = 100 Decomposition (days) 6/22/2008 P.W. Inglett 39 Ca arbon/nitrogen n Ratio N Mineralization/Immobilization [Aerobic] Immobilization Mineralization C/N ratio of soil humus/ microbial biomass Decomposition Period [days] 6/22/2008 P.W. Inglett 0 20

21 Regulators of Ammonification Substrate quality C/N ratio of the substrate Secondary compounds N forms (soluble vs. structural compounds) Microbial Activity Extracellular enzyme activity Supply of electron acceptors (Redox) Temperature ph 6/22/2008 P.W. Inglett 1 Mineralizable Nitrogen [EvergladesWCA2A] Mineralization Rate (mg N kg 1 d 1 ) y = x 52. R 2 = Extractable (mg N kg 1 ) 6/22/2008 P.W. Inglett 2 21

22 Fate of Ammonium Plant biomass N N 2 N 2 O (g) Nitrogen Fixation N 2 Litterfall NH 3 Volatilization NO 3 Nitrification NH Organic N Mineralization. Water Column NO Plant 3 [ ] s uptake Denitrification N 2, N 2 O (g) Organic N Peat accretion Microbial Biomass N [ ] s AEROBIC ANAEROBIC Adsorbed 6/22/2008 P.W. Inglett 3 Nitrogen Uptake by Rice ( 15 N) TtlN Total uptake tk Nitrogen uptake Added 15 N uptake Nuptake from Soil organic N Growing season 6/22/2008 P.W. Inglett 22

23 Ammonium Adsorption Aerobic NH Mg 2 K Ca 2 K Ca 2 K Ca 2 Mg 2 Mg 2 K K Ca 2 Adsorbed [Solids] K Ca 2 NH Mg 2 K Dissolved [Pore water] Ca 2 6/22/2008 P.W. Inglett 5 Ammonium Adsorption Anaerobic Fe 2 Ca 2 K Ca 2 Mg 2 Fe 2 Mn 2 K Mn 2 Mg 2 Mg 2 K Fe 2 Mn 2 Adsorbed [Solids] NH Ca 2 K Mg 2 Ca 2 Mn 2 Fe 2 K Dissolved [Pore water] Fe 2 6/22/2008 P.W. Inglett 6 23

NH Mg 2 NH K NH NH NH NH Mg 2 NH K NH NH

24 6/22/2008 P.W. Inglett 7 Ammonium Fixation Illite Clay Mineral Fixed Ammonium K Ca 2 Mg 2 NH K Mg 2 SiO layer NH Ca2 AlOOH layer K SiO layer NH Mg 2 NH K NH NH NH NH Mg 2 NH K NH NH Interlayer Space Interlayer Space Mg 2 Mg 2 K K Ca 2 6/22/2008 P.W. Inglett 8 2

25 Adsorption/Desorption Equilibrium NH NH Soil NH NH NH 6/22/2008 P.W. Inglett 9 Adsorption/Desorption Equilibrium Fixed Exchangeable Solution 6/22/2008 P.W. Inglett 50 25

26 S = K C S 0 ads = K [ ] fixed Am mmonium Adsorbed (mg N kg 1 ) () () K, Partition Coefficient E C 0 S 0 Porewater ammonium (mg N l 1 ) 6/22/2008 P.W. Inglett 51 Ammonium Adsorption Salinity 6/22/2008 P.W. Inglett 52 26

27 Increasing salinity 6/22/2008 P.W. Inglett 53 Ammonia Flux NH 3(g) (Volatilization) NH 3(g) Photosynthesis O 2 CH 2 O CO 2 H 2 O Respiration 2H CO 2 3 CO 2 H 2 O NH 3(aq) H (adsorbed) Water Soil 6/22/2008 P.W. Inglett 5 27

28 Diel ph changes in the Water Column ph System with low photosynthesis System with high photosynthesis :00 2:00 12:00 Time (h) 6/22/2008 P.W. Inglett 55 Ammonia Volatilization (assuming high ph) Floodwater depth Plant density SAV/Periphyton Density Temperature Wind speed Soil CEC 6/22/2008 P.W. Inglett 56 28

29 Ammonia Volatilization NH = NH H 3 Temperature High floodwater ph High soil ph High algal activity Plant density Cation exchange capacity of soil Wind speed Floodwater depth 6/22/2008 P.W. Inglett 57 Nitrification Plant biomass N N 2 N 2 O (g) Nitrogen Fixation N 2 Litterfall NH 3 Volatilization NO 3 Nitrification NH Organic N Mineralization. Water Column NO Plant 3 [ ] s uptake Denitrification N 2, N 2 O (g) Organic N Peat accretion Microbial Biomass N [ ] s AEROBIC ANAEROBIC Adsorbed 6/22/2008 P.W. Inglett 58 29

30 Nitrification NO NH NO2 NO3 Obligate aerobes (O 2 e acceptor) Common nitrifiers (autotrophs) Methanotrophs Heterotrophs t 6/22/2008 P.W. Inglett 59 Sites of Nitrification Aerobic Water column Aerobic Soil/Floodwater Interface O 2 O 2 bic Soil Aerob Anaerobic Soil Aerobic Root Zone O 2 6/22/2008 P.W. Inglett 60 30

31 Nitrification NO 2 Nitrosomonas ( Nitroso spp.) NO 2 NO 3 Nitrobacter ( Nitro spp.) Obligate aerobes (O 2 e acceptor) Energy/e source: NH Carbon source: CO 2 6/22/2008 P.W. Inglett 61 Nitrification Step I: Nitrosomonas ΔG o = 65 kcal/mole 2H 2 O NO 2 6e 8H 1½ O 2 6e 6H 3H 2 O 1 1 / 2 O 2 NO 2 3H 2 O H Step II: Nitrobacter ΔG o = 18 kcal/mole 2NO 2 2H 2 O 2NO 3 e H O 2 e H 2H 2 O 2NO 2 O 2 2NO 3 6/22/2008 P.W. Inglett 62 31

32 Heterotrophic Nitrification Bacteria and fungi Poorly studied Only dominant under high C/low N conditions Many facultative (reduce oxidized N to N 2) Nitrifier denitrification 6/22/2008 P.W. Inglett 63 Nitrification Ammonia NH 3 toxic to nitrifying bacteria ph optimum Sulfide S 2 toxic to nitrifying bacteria 6/22/2008 P.W. Inglett 6 32

33 Nitrification Ideal Conditions Inhibited NO 3 NO 2 C NO 2 NO 3 Time Time 6/22/2008 P.W. Inglett 65 Nitrification Hydroxylamine Oxygenases oxidoreductase d 2 e 2 e NH 2 OH [NOH] Chemical Oxygen stress 2 e 2 e N NO 2 O 2 NO 3 N 2 O NO 2 NO 3 Nitrite reductase Nitrite reductase 6/22/2008 P.W. Inglett 66 33

34 Inhibited Nitrification Leaky Pipe Model: NO NO NO 3 N 2 Nitrifiers N 2 O 2 Denitrifiers N 2 O 2 6/22/2008 P.W. Inglett 67 Nitrification Regulators: Ammonia concentration Oxygen availability Alkalinity and CO 2 Temperature Nitrifying population ph CEC 6/22/2008 P.W. Inglett 68 3

35 Organic N Volatilization (to atmosphere) Ammonification [NH 3 ] (g) NH Soluble ant/microbial Uptake NH Adsorbed [NO 3 ] Soil Particle Pl Live Organic N 6/22/2008 P.W. Inglett 69 Anaerobic Ammonium Oxidation: Anammox 6/22/2008 P.W. Inglett 70 Kuypers et al Nature 22:

36 Anaerobic Ammonium Oxidation (ANAMMOX) 5 3NO 3 N 2 9H 2 O 2H NH NO 2 N 2 2HO 2 6/22/2008 P.W. Inglett 71 ANAMMOX 6/22/2008 P.W. Inglett 72 36

37 Denitrification Plant biomass N N 2 N 2 O (g) Nitrogen Fixation N 2 Litterfall NH 3 Volatilization NO 3 Nitrification NH Organic N Mineralization. Water Column NO Plant 3 [ ] s uptake Denitrification N 2, N 2 O (g) Organic N Peat accretion Microbial Biomass N [ ] s AEROBIC ANAEROBIC Adsorbed 6/22/2008 P.W. Inglett 73 Pasteur, L Sur la fermentation nitreuse. Bull. Sot. Chim. Fr. 1:21. Nitrates, which the juice of beetroot naturally includes, decompose, and great quantities of nitrous vapor form at the surface of the vats 6/22/2008 P.W. Inglett 7 37

38 Dehérain and Maquenne, Sur la reduction des nitrates dans la terre arable. C. R. Acad. Sci. 95: From experience : Nitrate is reduced under certain conditions in arable land releasing nitrogen gas Nitrate reduction occurs in arable soil which contains a high organic matter We have observed that this reduction occurs when the soil atmosphere is completely stripped of oxygen 6/22/2008 P.W. Inglett 75 Nitrate Reduction Denitrification 5 e NO 3 N 2 Dissimilatory nitrate reduction to ammonia (DNRA) 8 e NO 3 NH Assimilatory nitrate reduction to ammonia NO 3 Proteins 6/22/2008 P.W. Inglett 76 38

39 Nitrate Reduction Assimilatory NH uptake for growth biosynthesis concentrationmain regulator Growth linked Occurs mainly in aerobic soils Insensitive to O 2 Dissimilatory Functions as an electron acceptor Oxygen concentration main regulator Linked to catabolic reactions Occurs in anaerobic soils Sensitive to O 2 6/22/2008 P.W. Inglett 77 Nitrate Reduction Denitrification NO 3 /NO 2 N 2 5 e transferred Low electron pressure Eh = mv O 2 transient conditions Facultative anaerobes DNRA NO 3 8 e transferred High electron pressure Eh = < 0 mv Lake sediments or permanent wetlands Obligate anaerobes 6/22/2008 P.W. Inglett 78 39

40 Regulators of Denitrification Low O 2 content Low Eh Presence of Electron Acceptor N Oxides Facultative Anaerobes Enzymes Electron Donor Carbon Source Organic carbon compounds Reduced sulfur compounds Temperature Nitrate diffusion/flux to anaerobic zones Plant root density 6/22/2008 P.W. Inglett 79 Sites of Nitrification/Denitrification Aerobic Water column Aerobic Soil/Floodwater Interface O 2 O 2 bic Soil Aerob Anaerobic Soil Aerobic Root Zone O 2 6/22/2008 P.W. Inglett 80 0

41 Dissimilatory Nitrate Reduction NO 3 NO 2 [HNO] [H 2N 2O 2 2] Biological NH 2 OH N 2 O [HNO] = Nitroxyl [H 2N 2O 2 2] = Hyponitrite NH 2 OH = Hydroxylamine N 2 DNRA Denitrification 6/22/2008 P.W. Inglett 81 Abiotic Nitrate Reduction ( Chemodenitrification ) 6/22/2008 P.W. Inglett 82 1

42 Abiotic Nitrate Reduction 6/22/2008 P.W. Inglett 83 Lithotrophic Nitrate Reduction Other potential e donors: S 2, H 2 6/22/2008 P.W. Inglett 8 2

43 N.R. Coupled to Fe(II) Oxidation: Paddy Soils w/ added NO 3 w/o added NO 3 w/ added NO 3 w/o added NO 3 Fe(II) Fe(III) Ratering and Schnell Env. Microbiol. 3(2), /22/2008 P.W. Inglett 85 N.R. Coupled to Fe(II) Oxidation NO 3 Fe(II) NO 2 Fe(III) N 2 NO 3 control Fe(III)culture NO 3 culture Fe(III)control Straub, et al Appl. Env. Microbiol. 62: /22/2008 P.W. Inglett 86 3

44 N 2 NH O 2 /Fe 3 NO 2 NO 3 CH? 6/22/2008 P.W. Inglett 87 6/22/2008 P.W. Inglett 88

45 Regulators of Denitrification Low O 2 content Low Eh Presence of Nitrogenous Oxides Heterotrophs: Carbon Source Organic carbon compounds, DOC Lithotrophs: Electron Source Reduced Fe, Mn, S compounds, H 2 Temperature Nitrate diffusion/flux to anaerobic zones Plant root density Nitrate uptake, O 2 loss 6/22/2008 P.W. Inglett 89 Denitrification Wetland Houghton Lake Wetland Inflow Zone Interior Zone Orange County ESAWT Inflow Zone Interior Zone EvergladesWCA2a Inflow Zone Interior Zone Denitrification Rate (mg N kg 1 day 1 ) /22/2008 P.W. Inglett 90 5

46 Coupled Nitrification Denitrification Nitrification rate depends on: Ammonification rate Ammonium flux into aerobic zone Denitrification rate depends on: Nitrification rate Nitrate flux into anaerobic zones Nitrificationdenitrification occurs in: Flooded soilwater column with aerobicanaerobic interfaces Aerobicanaerobic interfaces in the root zone Watertable fluctuations/ alternate flooding and draining 6/22/2008 P.W. Inglett 91 Coupled NitrificationDenitrification 6/22/2008 P.W. Inglett 92 From: Reddy (1989) 6

) 6 With Glucose Without Glucose Deni (mg 2 0 0 2 6 8 10 Distance (km)

47 Everglades WCA2A Nitrate source/ High C/Low Eh 10 Nitrate depleted/ High C/Low Eh Nitrate source/ Low C,P/Low Eh 8 trification Rate g N kg 1 hr 1 ) 6 With Glucose Without Glucose Deni (mg Distance (km) 6/22/2008 P.W. Inglett 93 Denitrification Walls: (Schipper et al. 2003) 7

48 ANAMMOX vs. Denitrification Supply of NO 2 Low NO 2 favors Denitrification, High NO 2 (>10mM) inhibits ANNAMOX Organic matter availability Higher DOC favors Denitrification Temperature ANNAMOX low Temp. 6/22/2008 P.W. Inglett 95 6/22/2008 P.W. Inglett 96 8

49 Denitrification vs. DNRA Supply of NO 3 Low NO 3 favors DNRA Organic matter availability High DOC favors DNRA Hydropattern Denitrifiers are largely facultative 6/22/2008 P.W. Inglett 97 (Of added 15 NO 3 ) ON 6/22/2008 P.W. Inglett 98 9

50 6/22/2008 P.W. Inglett 99 6/22/2008 P.W. Inglett

51 Potential Fate NO 3 Low Organic Matter (Low C:EA) Dissimila atory N N 2 2 N 2 N 2 NO 2 N 2 O H NO N 2 O High Organic Matter (High C:EA) Permanently Anaerobic Aerobic Anaerobic 6/22/2008 P.W. Inglett 101 Potential Fate Burgin and Hamilton Front Ecol Environ 5(2): /22/2008 P.W. Inglett

52 Nitrogen Cycling Plant biomass N N 2 N 2 O (g) Nitrogen Fixation N 2 Litterfall NH 3 Volatilization NO 3 Nitrification NH Organic N Mineralization. Water Column NO Plant 3 [ ] s uptake Denitrification N 2, N 2 O (g) Organic N Peat accretion Microbial Biomass N [ ] s AEROBIC ANAEROBIC Adsorbed 6/22/2008 P.W. Inglett

Amino sugars 5-10% Purine and Pyrimidine Bases trace amounts. Undescribed Lots - non-protein N Crude proteins Lignin - N

Amino sugars 5-10% Purine and Pyrimidine Bases trace amounts. Undescribed Lots - non-protein N Crude proteins Lignin - N N in Soil Note: soil concentrations can be anywhere, depending on vegetation, land use, etc. But a substantial amount indeed most (ca. 99%) soil nitrogen is organic Free amino acids trace amounts Amino