1. Nitrogen Cycle Topic 1016 D Matt Jakubik

2. Facts Earth’s Atmosphere is almost 80 % nitrogen (N2) Earth’s Atmosphere is almost 80 % nitrogen (N2) Most nitrogen is added to soil by rain or dust particles Most nitrogen is added to soil by rain or dust particles Some plants have bacteria help with nitrogen uptake Some plants have bacteria help with nitrogen uptake Others have aerial roots that can absorb from the air Others have aerial roots that can absorb from the air

5. Processes 1. Nitrogen Fixation 2. Mineralization 3. Nitrification 4. Immobilization 5. Denitrification

6. Nitrogen Fixation N2 taken from the atmosphere to the plant N2 taken from the atmosphere to the plant Nodules on legumes Nodules on legumes Bacteria-Rhizobium Bacteria-Rhizobium Ammonia applied to soil Ammonia applied to soil Soil picks up H+ Soil picks up H+

7. http://biology.kenyon.edu/courses/biol272/agriculture/nodulation2.jpg

8. Mineralization Also called ammonification Also called ammonification 99 % of soil nitrogen is organic nitrogen in organic matter 99 % of soil nitrogen is organic nitrogen in organic matter 1-2% is mineralized each year 1-2% is mineralized each year Nitrogen from manure Nitrogen from manure

9. Nitrification Oxidation of ammonium (NH4+) to nitrite (NO2-) to nitrate (NO3-) Oxidation of ammonium (NH4+) to nitrite (NO2-) to nitrate (NO3-) Two step process Two step process Process will not take place in saturated soils Process will not take place in saturated soils

10. Immobilization Conversion of Inorganic (minerals) Nitrogen to organic nitrogen Conversion of Inorganic (minerals) Nitrogen to organic nitrogen Stable in the soil Stable in the soil

11. Denitrification Reduction of nitrate or nitrite by microbial activity Reduction of nitrate or nitrite by microbial activity Gaseous process Gaseous process Escapes the soil Escapes the soil Prevents nitrogen in groundwater as overabundance occurs Prevents nitrogen in groundwater as overabundance occurs

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