6 - Impacts of Agriculture on the Atmosphere Flashcards
What are the two main positive impacts of agriculture on the atmosphere?
- Carbon Sequestration
- Carbon Storage
Define the atmosphere:
Layers of gases that envelope a planet, and is held in place by gravity
What are the four layers of the atmosphere? (Lowest to highest)
- Troposphere
- Stratosphere
- Mesosphere
- Thermosphere
Which is the innermost layer of the atmosphere?
Troposphere
In which layer of the atmosphere do convention currents redistribute heat and moisture around the globe?
Troposphere
How far up from the tropopause is the stratosphere?
~50km
True or False: The stratosphere has almost no water.
True
The stratosphere has 1,000x more _________ than the troposphere.
ozone
Why is ozone important for the stratosphere?
It absorbs UV light, which warms the upper part of the stratosphere.
Define Carbon Sequestration:
The process of capturing and storing atmospheric carbon dioxide
Why is carbon sequestration a positive influence of agriculture on the atmosphere?
Because it reduces the amount of carbon dioxide in the atmosphere and mitigates global climate change.
A Carbon ________ takes CO2 out of the atmosphere.
sink
A Carbon _________ reemits the carbon from the carbon sink.
source
What is an example of a carbon sink?
Forests, wetlands
What is an example of a carbon source?
Humans, burning fossil fuels, etc.
The Global Soil Carbon Pool = _______ Gt
2,500
The Atmospheric Carbon Pool = ____ Gt
760
The Biotic Carbon Pool = _______ Gt
560
Which, Organic or Inorganic, dominates the percentage in the Global Soil Carbon Pool?
Organic with 1,550 Gt
The Soil Carbon pool is ______x the size of the Atmospheric pool and _____x the size of the Biotic pool.
3.3x and 4.5x
Provide the main strategies to increase the Soil Carbon Pool:
- Agroforestry
- Cover Crops
- Efficient Irrigation
- Growing Energy Crops
- Improved Grazing
- Nutrient Management
- No-till Farming
- Mulching
- Soil Restoration
- Woodland Regeneration
- Water Conservation
Define Carbon Sequestration:
The capacity of agricultural lands and forests to remove carbon dioxide from the atmosphere.
Soils are the largest terrestrial _______________ on the planet.
carbon sink
Forests and stable grasslands are ______________.
carbon sinks
True or False: Carbon Sinks can store large amounts of carbon in their vegetation and root systems for long periods of time.
True
The Paris Climate Change Conference proposed the increase of the existing carbon in the topsoil by increased _____% per year.
0.4%
What are the two main negative impacts of agriculture on the atmosphere?
- GHG Emissions with Crop Production and Livestock
- Ozone Depleting Gases
In 2010, _____% of GHG emissions came from land use changes.
24%
Agricultural ecosystems remove carbon dioxide from the atmosphere by sequestering carbon in _______, __________________, and ________.
- biomass
- dead organic matter
- soils
True or False: The estimates of contribution from agriculture and land use changes to GHG emissions does not consider the CO2 removed.
True
Define the Greenhouse Effect:
GHGs (including water vapour) absorb the outgoing infrared energy and trap heat close to the Earth’s surface
Earth’s surface radiate __________ energy back toward space.
infrared
What are the three key gasses emitted by human activities?
- Carbon Dioxide
- Methane
- Nitrous Oxide
Which atmospheric gas is the most important cause of global warming?
Carbon Dioxide
_________ absorbs more infrared rays than Carbon Dioxide.
Methane
_______________ absorbs more infrared rays than both Carbon Dioxide and Methane.
Nitrous Oxide
The current level of Carbon Dioxide in the atmosphere is ________ppm.
412
Agriculture plays a __________ role in contributing to GHG emissions.
complex
What are the two principal sources of emission from the agriculture sector?
- Nitrous Oxide
- Methane
Where does nitrous oxide come from in agriculture?
fertilizers and manures
Where does methane come from in agriculture?
Livestock (ruminants and manure management) and rice cultivation
Net emissions of carbon dioxide from agricultural practices are _________________.
relatively small
What is the main activity in agriculture that causes carbon dioxide?
land use change (conversion of forested land to cropland)
Provide the three carbon dioxide source in agriculture:
- Fossil Fuel usage
- Land Use change
- Soil Tillage
Why is soil tillage considered a carbon source?
when you till the land, you are exposing the soil and encouraging decomposition, which releases more carbon dioxide.
Provide three types of carbon dioxide sinks in agriculture:
- Afforestation
- Reforestation
- Soil Improvement
Methane concentrations in the atmosphere have __________________ from preindustrial concentrations
risen steeply
What is one of the main methane sources in agriculture?
Enhanced livestock production
What livestock production practices produce the greatest amounts of methane?
- Raising ruminants
- Manure
- Rice Paddies
- Waste management
- Biomass burning
What is Enteric Fermentation?
The process of digestion within ruminants.
______________ are the main natural source of methane.
Wetlands
Define Ruminants:
Ruminants are large hoofed herbivorous grazing or browsing mammals that are able to acquire nutrients from plant-based food by fermenting it in a specialized stomach prior to digestion, principally through microbial actions.
Ruminants have ____ stomach compartments.
4
What makes ruminants different than non-ruminants?
They can break down cellulose, a complex carbohydrate found in plants that cannot be broken down by non-ruminants.
What are some examples of ruminants?
Sheep, goats, cattle, camel, and buffalo
Define Rumination:
Ruminants have the ability to regurgitate food from the stomach to the mouth for further chewing.
During digestion of plant material, methane is released from the ______.
gut
The more roughage in feed, the _______ methane is produced.
more
What is created when soils are flooded for a prolonged period?
Anaerobic conditions (low / no oxygen)
What two reactions produce GHGs?
- Denitrification: Result in nitrous oxide emissions.
- Methanogenesis: Methane emission
Methanogenesis and Denitrification produce what ?
Result in the production of nitrous oxide and methane!
What are the natural sources of Nitrous Oxide?
- From native nitrogen in soils; wetlands.
- Oxidation of ammonia in the atmosphere.
What are the anthropogenic sources of Nitrous Oxide?
- Use of nitrogen fertilizers in agriculture.
- Rice paddies
- Biomass burning
- Decay of livestock manure
- Fossil fuel combustion
Nitrous Oxide is generated in soil by two microbial processes in soils, which are:
- Denitrification
- Nitrification
Nitrification is a two-step process that involves:
The oxidation of ammonium nitrogen to nitrate
Nitrous oxide can be released as a ____________ at both stages of nitrification.
by-product
Define Denitrification:
Denitrification is a reductive sequence of reactions converting nitrate to dinitrogen gas via intermediates including N2O.
True or False: The U.S agricultural production sector is a net emitter of greenhouse gas emissions.
True
________________ is the single greatest contributor to GHG emission from the US agricultural production sector.
Agricultural soil management
Discovered in _______ that stratospheric ozone levels over South Pole were dropping rapidly during September and October.
1985
What is the main cause of the stratospheric ozone layer dropping over the South Pole?
Chlorofluorocarbons and Nitrous Oxide
At the ground-level, ozone is a pollutant, but in the stratosphere, it screens _____________.
UV radiation
A 1% decrease in ozone result in decreased ___________ production and reduced ___________ in the ocean, the basis of the food chain.
agricultural and plankton
Mitigation strategies are based on the type of _______ and the activity responsible for the emissions.
GHG
What are three ways of decreasing carbon dioxide pollution?
- Increasing carbon inputs and storing a larger proportion of C in the soil carbon pools
- Best management practices (BMP) that increase carbon inputs to the soil.
- Reduce losses of carbon from soil decomposition and erosion.
What are five ways of decreasing nitrous oxide pollution?
- Optimize nitrogen use by crop plants.
- Optimizing nitrogen use by livestock to reduce nitrogen excreted in urine and feces.
- Inhibitors to delay nitrification with the aim of retaining nitrogen in the form of ammonium.
- Better soil management
- Land-use Change
What are the three ways to reduce Methane emissions from livestock production?
- Dietary opportunities to manage methane production within the rumen.
- Increasing resource use efficiency - more production with less animals.
- Livestock reduction or replacements - through a change in market demand for meat and dairy products.
What are three ways of mitigating methane emissions from wetlands and rice production?
- Move away from permanently flooded systems, to more productive cultivation systems involving periodic flooding or dryland production.
- Better water management - multiple flooding and draining.
- Better crop residue management and fertilizer management.
