The Carbon CycleThe Carbon Cycle

Part of LifePart of Life

Part of AgriculturePart of Agriculture

AcknowledgmentsAcknowledgments

Don ReicoskyDon Reicosky - - Soil scientist with US Dept of Agriculture & Soil scientist with US Dept of Agriculture &

Agriculture Research ServiceAgriculture Research Service His research provided the inspiration and His research provided the inspiration and

information for these lessons.information for these lessons.

Part of all living things Part of all living things (and some non-living stuff)(and some non-living stuff)

Carbo

n

Key Words

• Photosynthesis

• Respiration

• Combustion

Important Summary PointsImportant Summary Points

Carbon (as COCarbon (as CO22) is ) is accumulatedaccumulated…… Photosynthesis uses sunlight to make Photosynthesis uses sunlight to make

carbohydrate from CO2.carbohydrate from CO2.

Carbon (as COCarbon (as CO22) is ) is released…released… Respiration - carbon is oxidized for energy.Respiration - carbon is oxidized for energy. Combustion - carbon is burnedCombustion - carbon is burned Weathering - rain (slightly acidic) weathers Weathering - rain (slightly acidic) weathers

calcium carbonate rockscalcium carbonate rocks

Carbon Cycle Has Been In Carbon Cycle Has Been In Balance for Millions of YearsBalance for Millions of Years

But in the last century COBut in the last century CO22 levels have levels have

been creeping up.been creeping up. Why?Why?

Carbon Cycle Has Been In Carbon Cycle Has Been In Balance for Millions of YearsBalance for Millions of Years

But in the last century COBut in the last century CO22 levels have levels have

been creeping up.been creeping up. Why? - (burning of fossil fuels).Why? - (burning of fossil fuels).

Greenhouse gasses, organic Greenhouse gasses, organic matter and agriculturematter and agriculture

1.1. COCO22 - the main greenhouse gas - the main greenhouse gas

2.2. Organic matter is mostly carbonOrganic matter is mostly carbon

3.3. Good soil high in organic matterGood soil high in organic matter

Review of Greenhouse gasses

The Greenhouse EffectThe Greenhouse EffectThink of the inside of a car in the Think of the inside of a car in the

summer…summer…

UV radiation from the sun passes through the glass,warms up the seats, and gets trapped

Heat (infrared) doesn’tpass back out through glass easily

Greenhouse gassesin the atmosphereact like the glass ina greenhouseor car.

The Greenhouse Effect is a The Greenhouse Effect is a Good ThingGood Thing

Because Mars has almost nogreenhouse gasses, heat fromthe sun goes back into outer space. Average temperature = -10 °F

Venus has too much of a Venus has too much of a good thing…good thing…

High CO2 levels on Venustrap too much heat. Temperature is nearly 800 °F.Even hotter than planet Mercury (350 °F),which is closer to the sun.

Major Greenhouse GassesMajor Greenhouse Gasses

Water vapor Water vapor Does much to Does much to keep planet warm. We keep planet warm. We have no control over water have no control over water vapor.vapor.

COCO22 is the most significant is the most significant

greenhouse gas. Levels greenhouse gas. Levels increasing because of fossil increasing because of fossil fuel burning. We should be fuel burning. We should be concerned about this one.concerned about this one.

Other Greenhouse GassesOther Greenhouse Gasses

MethaneMethane - from wetlands, ruminants and - from wetlands, ruminants and commercial production. 20-30 times more potent commercial production. 20-30 times more potent than COthan CO22. Levels going up slowly.. Levels going up slowly.

Nitrogen oxides (NONitrogen oxides (NOxx or N or NxxO)O) - formed during - formed during combustion from Ncombustion from N22 that’s in air. 200-300 times that’s in air. 200-300 times more potent than COmore potent than CO22..

Chloroflurocarbons (CFC’s)Chloroflurocarbons (CFC’s) - Foam insulation, - Foam insulation, refrigeration gas, used to be an aerosol refrigeration gas, used to be an aerosol propellant. Being phased out.propellant. Being phased out.

OzoneOzone - formed from lightning, electrical arcs, and - formed from lightning, electrical arcs, and a reaction of gas vapors and sunlight.a reaction of gas vapors and sunlight.

This is why we need to work onCO2.

Agriculture & the Carbon CycleAgriculture & the Carbon Cycle

Organic matter Organic matter (mostly carbon) (mostly carbon) affects soil quality.affects soil quality.

Crop residues create Crop residues create organic matter.organic matter.

Manure adds organic Manure adds organic matter.matter.

How Farmers Can HelpHow Farmers Can Help

Intensive tillage, burning Intensive tillage, burning fuels, use of equipment, fuels, use of equipment, adds COadds CO22 to the to the

atmosphereatmosphere

No-till systems remove No-till systems remove COCO22..

Images courtesy Don ReicoskyImages courtesy Don Reicosky

Why no-till systems are goodWhy no-till systems are good

Organic matter stays put.Organic matter stays put. Earthworms thrive.Earthworms thrive. Root channels remain undisturbed.Root channels remain undisturbed. Prevents soil from crusting.Prevents soil from crusting. Water holding capacity improves.Water holding capacity improves. Nutrient exchange improved.Nutrient exchange improved. Crop residues stay on surface.Crop residues stay on surface. Soil compaction reduced.Soil compaction reduced. Long term crop production improved.Long term crop production improved.

Important Summary Points forImportant Summary Points for

Greenhouse gasses like COGreenhouse gasses like CO22 help keep help keep

the planet warm. This is good. But too the planet warm. This is good. But too much COmuch CO22 may lead to global warming. may lead to global warming.

Agriculture can remove COAgriculture can remove CO22 from the from the

atmosphere if no-till systems are used.atmosphere if no-till systems are used. No-till systems also provide a multitude of No-till systems also provide a multitude of

advantages, and increase long-term crop advantages, and increase long-term crop production.production.