Part of Life Part of Agriculture The Carbon Cycle Part of Life Part of Agriculture

Acknowledgments Don Reicosky - Soil scientist with US Dept of Agriculture & Agriculture Research Service His research provided the inspiration and information for these lessons.

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

Key Words Photosynthesis Respiration Combustion

Important Summary Points Carbon (as CO2) is accumulated… Photosynthesis uses sunlight to make carbohydrate from CO2. Carbon (as CO2) is released… Respiration - carbon is oxidized for energy. Combustion - carbon is burned Weathering - rain (slightly acidic) weathers calcium carbonate rocks

Carbon Cycle Has Been In Balance for Millions of Years But in the last century CO2 levels have been creeping up. Why?

Carbon Cycle Has Been In Balance for Millions of Years But in the last century CO2 levels have been creeping up. Why? - (burning of fossil fuels).

Greenhouse gasses, organic matter and agriculture Review of Greenhouse gasses Greenhouse gasses, organic matter and agriculture CO2 - the main greenhouse gas Organic matter is mostly carbon Good soil high in organic matter

The Greenhouse Effect Think of the inside of a car in the summer… UV radiation from the sun passes through the glass, warms up the seats, and gets trapped Heat (infrared) doesn’t pass back out through glass easily

Greenhouse gasses in the atmosphere act like the glass in a greenhouse or car.

The Greenhouse Effect is a Good Thing Because Mars has almost no greenhouse gasses, heat from the sun goes back into outer space. Average temperature = -10 °F

Venus has too much of a good thing… High CO2 levels on Venus trap too much heat. Temperature is nearly 800 °F. Even hotter than planet Mercury (350 °F), which is closer to the sun.

Major Greenhouse Gasses Water vapor Does much to keep planet warm. We have no control over water vapor. CO2 is the most significant greenhouse gas. Levels increasing because of fossil fuel burning. We should be concerned about this one.

Other Greenhouse Gasses Methane - from wetlands, ruminants and commercial production. 20-30 times more potent than CO2. Levels going up slowly. Nitrogen oxides (NOx or NxO) - formed during combustion from N2 that’s in air. 200-300 times more potent than CO2. Chloroflurocarbons (CFC’s) - Foam insulation, refrigeration gas, used to be an aerosol propellant. Being phased out. Ozone - formed from lightning, electrical arcs, and a reaction of gas vapors and sunlight.

This is why we need to work on CO2.

Agriculture & the Carbon Cycle Organic matter (mostly carbon) affects soil quality. Crop residues create organic matter. Manure adds organic matter.

How Farmers Can Help Intensive tillage, burning fuels, use of equipment, adds CO2 to the atmosphere No-till systems remove CO2. Images courtesy Don Reicosky

Why no-till systems are good Organic matter stays put. Earthworms thrive. Root channels remain undisturbed. Prevents soil from crusting. Water holding capacity improves. Nutrient exchange improved. Crop residues stay on surface. Soil compaction reduced. Long term crop production improved.

Important Summary Points for Greenhouse gasses like CO2 help keep the planet warm. This is good. But too much CO2 may lead to global warming. Agriculture can remove CO2 from the atmosphere if no-till systems are used. No-till systems also provide a multitude of advantages, and increase long-term crop production.

Carbon Sequestration and Carbon Credits Soon power plants may have to pay for the carbon they emit. Farmers may get compensated for the carbon they remove from the atmosphere.

Remember our carbon cycle CO2 Photosynthesis (CO2 + Sunlight) 1/2 ton per acre Intensive Tillage

With no-till, plants put CO2 into the soil and it stays put Photosynthesis (CO2 + Sunlight) CO2 No-till systems

Should Farmers Be Paid for For the Carbon They Put Back into the Soil Should Farmers Be Paid for For the Carbon They Put Back into the Soil? Maybe

Here’s an Imaginary Example Power Plant must reduce carbon emissions or pay $1,000/day in penalties

So the Power Plant offers to buy carbon credits from a group of farmers. $250,000

Here’s a Real Example In 2002, Entergy paid $75,000 to Pacific Northwest Direct Seed Association. This deal was arranged to save (sequester) 3,000 tons of CO2 per year. 6,470 no till acres.

No-till really helps - here are some other methods Deep ocean injection (being researched). Oil and gas reservoirs (use CO2 to push out oil or gas). Un-mineable coal seams (replace methane with CO2). Saline formations (adsorb CO2 onto salt). Store as minerals (magnesium carbonate).

Carbon Sequestration Summary Points We can help the fossil carbon cycle… By managing the biological carbon cycle.

Agriculture’s role in the carbon cycle. Conservation Agriculture (Direct Seeding or No-Till farming) CO2 CO2 Making Soil Out of Oil O2 Agriculture’s role in the carbon cycle. CO2 combustion photosynthesis CO2 O2 O2 respiration CO2 Credit : Jim Kinsella, 1998