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N-CycleCore Training
Feb 9th In-Service
N-Cycle
OM 2 OM
Processes 2 N
Processes 3 Sinks 4 losses 5 additions
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.
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
Nitrogen Processes
Amminization and Ammonification› OM converted to NH4
Nitrification› NH4 converter to NO3
Ammonium + charge and Immobile Nitrate – charge and mobile
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
4 Losses
Leaching› 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.
pH and Temp are Drivers
Additions
Lightning and Rainfall Biological N Fixation Decomposition Industrial Fixation Fertilization
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
Applications within The N-Cycle
Understanding Inhibitors› Urease and Nitrification
Fields had High N in October and N deficient by Dec.
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.
Thank you!!!
Brian Arnall373 Ag Hall405-744-1722b.arnall@okstate.eduPresentation available @
www.npk.okstate.eduTwitter: @OSU_NPKYouTube Channel: OSUNPK
www.extensionnews.okstate.edu
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