10 21 nitrogen cycle2
DESCRIPTION
TRANSCRIPT
![Page 1: 10 21 Nitrogen Cycle2](https://reader035.vdocuments.us/reader035/viewer/2022081413/54625c01b4af9f531c8b4745/html5/thumbnails/1.jpg)
Nitrogen Cycle
Term: Legume
![Page 2: 10 21 Nitrogen Cycle2](https://reader035.vdocuments.us/reader035/viewer/2022081413/54625c01b4af9f531c8b4745/html5/thumbnails/2.jpg)
www.sciencedaily.com/releases/2009/04/090414110818.htm
• Go to sciencedaily.com & search for soybeans & aphids
• Read the Article from April 20th
• Are rhizobia specific to legume species• Do naturally occurring rhizobia or
commercially inoculated rhizobia provide better resistance?
• Does the source of the rhizobia influence the effectiveness of nitrogen fixation?
![Page 3: 10 21 Nitrogen Cycle2](https://reader035.vdocuments.us/reader035/viewer/2022081413/54625c01b4af9f531c8b4745/html5/thumbnails/3.jpg)
Legumes
• Plants that have a symbiotic relationship with bacteria that grow in nodules on their roots.
• Soybeans – widely rotated with corn crops to revitalize soil
• Vetch & Clovers – Cover crops – green manure
• Clovers & Alfalfa - grown to improve hay crops & pasture.
![Page 4: 10 21 Nitrogen Cycle2](https://reader035.vdocuments.us/reader035/viewer/2022081413/54625c01b4af9f531c8b4745/html5/thumbnails/4.jpg)
Other Legumes
• Red bud trees• Locust Trees• Beans• Peas• Most plants that form Pods
![Page 5: 10 21 Nitrogen Cycle2](https://reader035.vdocuments.us/reader035/viewer/2022081413/54625c01b4af9f531c8b4745/html5/thumbnails/5.jpg)
Rhizobia• Rhizobia are specific to legume
species• The naturally occurring bacteria
were more effective at creating resistance against the aphid than the imported bacteria.
• Older generations of rhizobia are more effective than the new ones
• The rhizobia compete for space to grow on the roots
• Naturalized rhizobia are as effective in nitrogen fixation as the commercial ones.
![Page 6: 10 21 Nitrogen Cycle2](https://reader035.vdocuments.us/reader035/viewer/2022081413/54625c01b4af9f531c8b4745/html5/thumbnails/6.jpg)
Nitrogen & Fertilizer• Industrialized countries began producing
chemical fertilizers after WWI– Haber Process
• Manufactured nitrogen begins with the production of ammonia (NH3).
• Ammonia is a gas that is produced when atmospheric N2 is combined with hydrogen from fossil fuels - also called anhydrous ammonia
• Stored under pressure• When fuel prices ↑, fertilizer prices ↑
![Page 7: 10 21 Nitrogen Cycle2](https://reader035.vdocuments.us/reader035/viewer/2022081413/54625c01b4af9f531c8b4745/html5/thumbnails/7.jpg)
Ammonia Fertilizers
NH3
Nitric Acid
Sulfuric Acid
Phosphoric Acid
Carbon Dioxide
Anhydrous Ammonia
Ammonium Nitrate
Ammonium Sulfate
Ammonium Phosphate
Urea
![Page 8: 10 21 Nitrogen Cycle2](https://reader035.vdocuments.us/reader035/viewer/2022081413/54625c01b4af9f531c8b4745/html5/thumbnails/8.jpg)
Nitrogen Fixation
• Conversion of Inert N2 into bio-usable forms
• atmospheric fixation by lightning • biological fixation by certain microbes
– alone– symbiotic relationship with some plants and
animals • industrial fixation – Haber Process
![Page 9: 10 21 Nitrogen Cycle2](https://reader035.vdocuments.us/reader035/viewer/2022081413/54625c01b4af9f531c8b4745/html5/thumbnails/9.jpg)
Nitrification
• Nitrification – whatever form of ammonia is applied to the soil, it must be converted to be used by plants– NH3 + Nitrosomonas → NO2
– NO2 + Nitrobacter → NO3
• NO3 Very soluble form– Only held loosely by soil colloids (clay & humus)– ~ 5% of NO3 dissolves in water and is lost by leaching
![Page 10: 10 21 Nitrogen Cycle2](https://reader035.vdocuments.us/reader035/viewer/2022081413/54625c01b4af9f531c8b4745/html5/thumbnails/10.jpg)
Denitrification
• In saturated soils• Anaerobic Conditions (No oxygen)• Bacteria convert NO3 to elemental
Nitrogen (N2) which is a gas and returns to atmosphere
• 30 -40% of applied Nitrogen if area has been flooded for 3-5 days
![Page 11: 10 21 Nitrogen Cycle2](https://reader035.vdocuments.us/reader035/viewer/2022081413/54625c01b4af9f531c8b4745/html5/thumbnails/11.jpg)
Volatilization
• Occurs when urea is converted to ammonium carbonate
• Ammonium carbonate breaks down in warm moist soils to ammonia gas and carbon dioxide
• Ammonia gas evaporates into the atmosphere.
![Page 12: 10 21 Nitrogen Cycle2](https://reader035.vdocuments.us/reader035/viewer/2022081413/54625c01b4af9f531c8b4745/html5/thumbnails/12.jpg)
Decay• The proteins made by plants enter and pass
through food webs just as carbohydrates do. • At each trophic level, their metabolism produces
organic nitrogen compounds that return to the environment, chiefly in excretions.
• The final beneficiaries of these materials are microorganisms of decay.
• They break down the molecules in excretions and dead organisms into ammonia.
![Page 13: 10 21 Nitrogen Cycle2](https://reader035.vdocuments.us/reader035/viewer/2022081413/54625c01b4af9f531c8b4745/html5/thumbnails/13.jpg)
Carbon – Nitrogen Ratio• The rate of decomposition of decaying plants
depends on the C:N ratio• C:N ratios of 25:1 or less decompose quickly
and make Nitrogen available to plants (mineralization)
• C:N ratios of 25:1 or more cannot decompose with out drawing nitrogen out of the soil (immobilization)
• Humus has a C:N ratio of 12:1 and has completely decomposed
• Implications for mulch and composting
![Page 14: 10 21 Nitrogen Cycle2](https://reader035.vdocuments.us/reader035/viewer/2022081413/54625c01b4af9f531c8b4745/html5/thumbnails/14.jpg)
The Nitrogen Cycle
• N2 - Nitrogen Gas 78% of air - Inert
• NH4 – Ammonium ion – Made by bacteria
• NH3 – Ammonia - Made by Haber-Bosch process. Industrial N fixation
• NO2 – Nitrite ion – Very toxic to plants – Bacteria convert it to Nitrate
• NO3 – Nitrate ion – Form used by plants Very soluble – quickly leaches out of soil
![Page 15: 10 21 Nitrogen Cycle2](https://reader035.vdocuments.us/reader035/viewer/2022081413/54625c01b4af9f531c8b4745/html5/thumbnails/15.jpg)