1. Core Training Feb 9th In-Service
N-Cycle
Core Training
Feb 9th In-Service

2. N-Cycle OM
2 OM Processes
2 N Processes
3 Sinks
4 losses
5 additions

3. Organic Matter Central point of the Nitrogen Cycle
In an acre furrow slice 1000 lbs N per 1% OM
A continuous flow of N into and out of OM.

5. Organic Matter Processes
Immobilization
NO3 and NH4 tied up into OM
Mineralization
OM decomposed into NO3 and NH4
High Carbon (straw)= Immobilization
Low Nitrogen (alfalfa) = Mineralization

7. Nitrogen Processes Amminization and Ammonification Nitrification
OM converted to NH4
Nitrification
NH4 converter to NO3
Ammonium + charge and Immobile
Nitrate – charge and mobile

9. Nitrogen Sinks Large Amounts of Nitrogen located in these pools.
Atmosphere : 78% N in the form of the diatomic gas N2
Nitrate Pool
Microbial Sink

11. 4 Losses Leaching Ammonia Volatilization Denitrification Plant Loss
NO3 – follows water flow.
Ammonia Volatilization
NH4 at a pH >7 H is stripped off and NH3 (gas) formed.
Denitrification
NO3 in waterlogged soil. Microbes strip O off
Plant Loss
NO3 and NH4 converted to NH3 in plant, in stress NH3 gassed off.

13. pH and Temp are Drivers

14. Additions Lightning and Rainfall Biological N Fixation Decomposition
Industrial Fixation
Fertilization

16. Remember Organic Matter
Organic Matter is the Driver
Annual N need is determined by Mineralization and Immobilization
Environment, temp and rainfall, drives Mineralization and Immobilization

17. Applications within The N-Cycle
Understanding Inhibitors
Urease and Nitrification
Fields had High N in October and N deficient by Dec.

18. Definitions
Organic-N: N that is bound in organic material in the form of amino acids and proteins.
Mineral-N: N that is not bound in organic material, examples are ammonium and nitrate-N
Ammonia: A gaseous form of N (NH3).
Ammonium: A positively charged ion of N (NH4+).
Diatomical-N: N in the atmosphere (N2)
Nitrate-N: A negatively charged ion of N (NO3-).
Mineralization : The release of N in the inorganic form (ammonia) from organic bound N. As organic matter is decayed ammonia quickly reacts with soil water to form ammonium, thus the first measurable product of mineralization is
usually ammonium-N.
Immobilization: Assimilation of inorganic N (NH4+and NO3- ) by microorganisms.
Nitrification: Oxidation of ammonium N to nitrate N by autotrophic microorganisms in an aerobic environment.
Denitrification: Reduction of nitrate N to nitrous oxide (N2O) or diatomical N gases by heterotrophic microorganisms in an anaerobic environment.
Autotrophic: A broad class of microorganisms that obtains its energy from the oxidation of inorganic compounds (or sunlight) and carbon from carbon dioxide.
Heterotrophic: A broad class of microorganisms that obtains its energy and carbon from preformed organic nutrients.
Volatilization: Loss of gaseous N from soil, usually after N has been transformed from ionic or non-gaseous chemical forms.

19. Thank you!!! Brian Arnall 373 Ag Hall b.arnall@okstate.edu
Brian Arnall
373 Ag Hall
Presentation
YouTube Channel: OSUNPK