Vocabulary Nitrification- Chem rxn that converts Ammonium (NH 4 + ) to Nitrate (NO 3 - ) and Nitrite (NO 2 - ) Denitrification- Chem rxn that converts Nitrate and Nitrite ions into Nitrogen gas (N 2 ) and Nitrous Oxide (N 2 O) Nitrogen fixation- Conversion of N 2 from atmosphere into ammonia and ammonium ions for plants and animals Decomposition- Plants and animals decompose and break down supplying the soil with Nitrogen Absorption- Plants absorb nitrogen from the soil Consumption- Animals eat plants that have nitrogen in them
Figure 36.16 Nitrogen (N 2 ) in atmosphere Amino acids and proteins in plants and animals Consumption Absorption by plants Denitrifying bacteria Denitrification Nitrates (NO 3 – ) Nitrifying bacteria Nitrifcation Detritus Detritivores Decomposition Ammonium (NH 4 + ) Nitrogen fixation Nitrogen-fixing bacteria in soil Nitrogen-fixing bacteria in root nodules of legumes Nitrogen fixation
Nitrogen Fixation Convert N 2 from atmosphere to a usable form: NH 4 +1 or NO 3 -1 Ammonia or Nitrate Three methods of Nitrogen Fixation: 1.atmospheric fixation by lightning 2.biological fixation by certain microbes - alone or in a symbiotic relationship with plants
The nitrogen cycle relies heavily on bacteria Nitrogen is plentiful in the atmosphere as N 2 –But plants cannot use N 2 Various bacteria in soil (and legume root nodules) convert N 2 to nitrogen compounds that plants can use –Ammonium (NH 4 + ) and nitrate (NO 3 – ) Nitrogen Fixation continued…
Nitrogen fixation by lightning Nitrates are produced by forest fires and lightning.
Nitrogen fixation by bacteria Atmospheric nitrogen (78% of atmosphere) is chemically fixed by bacteria to ammonium (NH 4 +1 ), which is used by plants as a fertilizer.
A single atom of nitrogen can have sequential effects in various parts of the environment after it has been converted from non-reactive N2 to a reactive form during energy or food production. N Cascade