THE NITROGEN CYCLE THE NITROGEN CYCLE All living

THE NITROGEN CYCLE

THE NITROGEN CYCLE § All living things need nitrogen to make proteins. § Almost 80% of the atmosphere is nitrogen, however, nitrogen cannot be used directly by living things. § Nitrogen must be converted or “fixed” into a form that plants and animals can use.

NITROGEN FIXATION § Defn: The production of soluble nitrogenous compounds. § Nitrogen is fixed in 3 ways: 1. By nitrogen-fixing bacteria in soil or water 2. By By nitrogen-fixing bacteria living in plant/legume roots (Fertilizers) 3. By lightening (Nitrogen + Hydrogen + Oxygen)

Nitrogen Fixation § Nitrogen (N 2) is converted into 3 forms that can be used by plants and animals: 1. Ammonium - NH 4+ 2. Nitrite - NO 23. Nitrate - NO 3 -

Where To Find Each Form of Nitrogen § Nitrogen gas - atmosphere § Ammonium - soil or water § Nitrates and Nitrites - soil, sometimes water

THE NITROGEN CYCLE § The nitrogen cycle has three main components: § Ammonification- produces ammonium § Nitrification- produces nitrates § Denitrification- produces gaseous nitrogen

Ammonification § Ammonium is produced when nitrogen in animal waste and dead organisms decompose. § This is done by special ammonifying bacteria in soil and water. Organic Nitrogen (proteins) --> Ammonia --> Ammonium (Toxic)

Ammonification B a c t e r i a Excretions (contain Nitrogen) Proteins in Animal Contain Nitrogen Converted to Ammonium (NH 4+) Protein in Plants Death & Decomposition Bacteria

Ammonification § Plants (producers) can absorb ammonium from soil and use it in plant proteins. § Animals (consumers) can then eat ammonium in plant proteins and use it in their bodies.

Nitrification § Nitrate is produced when: § 1. Ammonium is converted to nitrite and then to nitrate. § 2. nitrogen gas is converted to nitrate. § This is done by nitrifying soil or water bacteria. § Nitrate is the form of nitrogen that is easiest for plants to use. § Plants absorb it from the soil.

Nitrification 1 Nitrate (NO 3 -) Ammonium (NH 4+) Nitrite (NO 2 -) Nitrogen Fixing Bacteria Nitrite Lost from Soil Leaching

Nitrification 2 Nitrogen Gas in Atmosphere Nitrate (NO 3 -)

Nitrification § Nitrite and Nitrate can also be used by producers to make proteins. § The producers are then eaten by consumers and the nitrogen in their proteins is transferred to the consumer.

�Denitrification § Occurs when denitrifying soil or water bacteria convert ammonia, nitrite, or nitrate back to nitrogen gas. § Nitrogen gas is release into the atmosphere.

Denitrification Nitrogen Gas in Atmosphere Nitrate (NO 3 -)

ASSIGNMENT………

assignment § Page 45 #1 -5 § Chart on page 51 - get two comparisons and two contrasting features.