8

Growing Carbon:

A New Crop That

Helps Agricultural

Producers and the

Climate Too
1

Climate change could cause more droughts

and floods.

Climate Change and the

Greenhouse Effect

As a natural part of the Earth’s atmosphere,

greenhouse gases, such as carbon dioxide,

trap heat in the same way that glass does in

a greenhouse. Without them, the Earth

would be too cold for agriculture. But

people are increasing the amount of these

gases in the atmosphere by burning coal,

oil, and natural gas to heat their homes,

power their cars, and run the machinery in

their factories. Other human activities,

such as manufacturing chemicals, producing cement, raising cattle, and clearing

land, also release greenhouse gases.

The accumulation of these gases in the

atmosphere is likely to cause changes in

temperature, rain, snowfall, and other

aspects of the climate. In 1995, a group of

more than 2,000 of the world’s leading

scientists (the Intergovernmental Panel on

Climate Change) concluded that “the

balance of evidence suggests a discernible

human influence on global climate.”

Computer models indicate that the future

warming will be faster and greater than any

in the last 10,000 years, indeed since the

dawn of agricultural societies. In coming

years we could see:

• Warmer temperatures on average,

especially at night.

• More extremely hot days or heat waves.

• Longer growing seasons.

• Changes in seasonal rain and snowfall.

• More frequent or intense droughts or

floods.

• Changes in the occurrence of weeds and

insect pests.

Everyone talks about the weather, but no one does anything about it. This old saying

may no longer be quite true. While day-to-day weather is hard to predict, more and more

evidence suggests that human activities are beginning to change the overall climate of our

planet, in ways that may hurt agricultural producers. But producers have opportunities to

help efforts to slow climate change, to build a cushion against its harmful effects, and

perhaps to grow a new crop—carbon.
2

Improved

grazing

management

can reduce

greenhouse

gas emissions

and increase

carbon

sequestration.

What Could Happen to

Agriculture in the United States

as the Climate Changes?

Agriculture in the United States has been

able to adapt to weather fluctuations in the

past: farmers changed their crops or

varieties of crops, planting and harvest

times, and use of fertilizers, pesticides, and

irrigation. Studies of the potential impacts

of climate change on agriculture estimate

that we will continue to be able to feed

people in our country and many others

throughout the world.

For individual farms, however, the changes

in climate could be disruptive and expensive. Although elevated levels of carbon

dioxide in the atmosphere may increase

crop growth, changes in climate may cause

yield reductions or crop losses.

How Agricultural Producers

Reduce Greenhouse Gas

Emissions

Agriculture produces substantial amounts

of two greenhouse gases, methane and

nitrous oxide, and minor amounts of

carbon dioxide. Many practices that are

adopted by agricultural producers for a

variety of benefits also reduce emissions of

greenhouse gases to the atmosphere and

thereby help slow climate change. Some

of these practices are:

• Conserving fuel by limiting the number

and intensity of field operations.

• Using conservation or no-till cultivation

systems to reduce carbon dioxide

emissions from the soil.

• Using soil tests to apply nitrogen

fertilizers only when and where they are

needed. Using less nitrogen fertilizer

can decrease emissions of nitrous oxide.

• Management of grass-based animal

production systems using, for example,

rotational grazing and improved

forages. This decreases methane emissions from ruminant animal production.

• Using methane-recovery systems for

liquid manure, such as digesters or

covered lagoons, to reduce methane

2
3

Methane-recovery systems can generate

energy from biogases.

emissions and provide on-farm sources

of biogas fuel for large livestock operations.

• Using aerobic systems such as

composting to reduce manure methane

production from small livestock operations.

• Improving animal production efficiency

by, for example, improving nutrient

balance and quality of livestock feed to

reduce methane emissions produced by

animal digestion.

• Producing “biofuels” as a substitute for

fossil fuels to reduce net carbon dioxide

emissions. Plant material can be burned

to generate energy or can be converted

into fuels. Potential biofuels include

traditional agricultural crops (such as

corn and soybeans), dedicated biofuel

crops (such as switchgrass and shortrotation trees), and by-products of food

and fiber processing.

How Producers Increase the

Storage of Carbon on

Agricultural Lands

Agricultural producers also influence

climate by increasing the storage of carbon

on agricultural lands. Carbon is a component of carbon dioxide, the most common

greenhouse gas. Storing, or “sequestering,”

carbon in soil as organic matter and in trees

helps reduce the amount of carbon dioxide

in the atmosphere. This is why soil and

vegetation are sometimes called carbon

“sinks.” Conservation practices, most often

adopted for other benefits, that increase

carbon storage include:

Conservation

buffers sequester carbon in

soil and

vegetation.
4

Crop rotations and

reduced tillage

improve soil quality

and sequester soil

organic carbon.

• Using conservation or no-till cultivation

systems.

• Rotating crops and incorporating small

grains, hay, legumes, or other crops into

rotations.

• Planting cover crops.

• Minimizing or eliminating summer

fallow.

• Managing nutrients and irrigation

efficiently and effectively.

• Applying manure, compost, and other

organic amendments according to

nutrient management plans.

• Improving pasture and rangeland soils

through grazing, vegetation, and fire

management.

• Installing permanently vegetated

conservation buffers, such as windbreaks, grass waterways, filter strips,

and riparian buffers.

• Restoring or protecting wetlands.

(Carbon sequestration outpaces methane

emissions in most wetlands.)

• Converting marginal agricultural land to

perennial grassland or forest.

• Managing woodlands to conserve soil

and increase biomass.

• Adopting agroforestry practices that

incorporate trees into agricultural

operations.

What Are the Benefits of These

Practices?

Practices that reduce greenhouse gas

emissions offer multiple economic and

environmental benefits. For example,

reducing the number and intensity of field

operations saves money, time, and labor.

Using nitrogen fertilizers more efficiently

and not overusing them lowers fertilizer

costs while maintaining yields. Better

management of nitrogen fertilizers means

that fields lose fewer nutrients to ground

and surface waters. Methane-recovery

systems may pay for themselves within a

few years because the methane can be

burned right on the farm for energy.

Composts provide nutrients and soil

improvement for on- or off-farm application. Such systems also help keep waterways cleaner.

Practices that increase the amount of soil

carbon also reduce soil erosion and improve soil quality. As its organic carbon

content increases, a soil is better able to

hold water and nutrients. This increases its

productivity, while protecting water quality
5

Improved soil quality with stored

carbon is value in hand.

and minimizing flooding. Higher-quality

soil also helps crops withstand drought,

cuts irrigation needs, and increases the

long-term productivity of farmed land.

Keeping crop residues on fields, maintaining vegetated buffers, and using

agroforestry practices improve air and

water quality by reducing erosion. These

practices also enhance wildlife habitat by

providing food and shelter, and can provide

additional farm income.

Some of the practices that decrease greenhouse gas emissions or sequester carbon

require a capital investment or increase

farm-operating costs. The federal Conservation Reserve Program (CRP), the

Wetlands Reserve Program (WRP),

AgSTAR, and the Environmental Quality

Incentives Program (EQIP) provide

assistance to help farmers adopt these

beneficial practices.

Agricultural research institutions are

continually seeking to develop more

effective production systems that will help

farmers further improve conservation.

International Climate Change

Agreements and U.S. Agriculture

Scientific evidence has caused nations to

adopt a series of international agreements

aimed at slowing human-caused climate

changes. The first agreement, the 1992

Framework Convention on Climate

Change (the Rio Treaty), requires all

countries to identify, inventory, and work

voluntarily to reduce their greenhouse gas

emissions. The United States ratified the

Rio Treaty in 1992 by a unanimous vote of

the U.S. Senate.

The second agreement, the 1997 Kyoto

Protocol, would protect the Earth’s climate

by committing, as a first step, industrialized countries to decrease their greenhouse

gas emissions by an average of 5 percent

from 1990 levels for a five-year period

from 2008 to 2012.

Although this new climate agreement has

not yet been approved by the U.S. Senate,

this agreement, or future domestic legislation, could create incentives to reduce

greenhouse gas emissions from agriculture.
6

It could also create opportunities for

farmers to supplement their income. First,

a climate agreement or legislation could

open new markets for biofuel crops and

agricultural by-products. Even though

farmers have been producing biofuels for a

long time, the demand for them could

increase. Second, a climate agreement or

legislation could create a market for an

entirely new agricultural commodity—

carbon.

A Market for Carbon?

A climate agreement or domestic legislation could allow the United States and

other nations to meet greenhouse gas

emissions targets by a variety of means, so

that they could choose the most costeffective options. One might be to give

credits to agricultural producers who

increase their stores of carbon in the soil or

in trees. Producers could then save the

credits or sell them to others (for example,

to electric power companies) that want

them in order to offset their own greenhouse gas emissions.

Earning credits for storing more carbon

would provide an additional source of

income for agricultural producers—a

carbon crop. The U.S. Department of

Agriculture (USDA) Agricultural Research

Service and Natural Resources Conservation Service are investigating how soil

conservation practices increase soil carbon

storage. They are also developing fieldlevel computer models to estimate the

amount of carbon stored by individual

production systems. Such models would

make it easier for producers to participate

in a program for crediting carbon. The

potential market for carbon credits could

be substantial, and agricultural producers

could benefit. Producers and the locally-led

conservation process have an important

role to play on this issue.

To Learn More About . . .

• Agricultural practices and conservation

programs mentioned in this brochure,

contact your local USDA Service Center

or your local Resource Conservation and

Development Council office. Or visit

the following websites:

USDA Natural Resources Conservation

Service: www.nrcs.usda.gov

National Association of Conservation

Districts: www.nacdnet.org

National Association of Resource

Conservation and Development Councils: www.RCDnet.org

USDA National Agroforestry Center:

www.unl.edu/nac

National Association of State Conservation Agencies: www.nascanet.org

Soil and Water Conservation Society:

www.swcs.org

Conservation Technology Information

Center:

www.ctic.purdue.edu/CTIC/CTIC.html
7

The U.S. Department of Agriculture (USDA) is an

equal opportunity provider and employer.

• Research on agriculture and climate

change, visit the USDA Agricultural

Research Service’s website at:

 www.nps.ars.usda.gov

• USDA global change activities, visit the

The USDA Global Change Program

Office website at:

www.usda.gov/agency/oce/gcpo/

index.htm

• Climate change, contact

Environmental Defense:

www.environmentaldefense.org

1-800-684-3322

• Biofuels, visit the National Biodiesel

Board website at www.biodiesel.org, or

call their headquarters at:

1-800-841-5849

For additional copies of this

brochure:

Download off the Soil and Water Conservation Society website at www.swcs.org or

request a copy by calling 1 888

LANDCARE (1 888-526-3227) or email

landcare@swcs.org

This brochure has been sponsored by the

following organizations:

USDA Natural Resources

Conservation Service provides

leadership in a partnership effort to

help people conserve, improve, and

sustain our natural resources and

environment.

USDA National Agroforestry Center

accelerates the development and

application of agroforestry technologies to attain more economically,

environmentally, and socially sustainable land-use systems.

Environmental Defense is a national

nonprofit organization with 300,000

members that links science, economics, and law to create innovative,

equitable, and economically sensible

solutions to today’s environmental

problems.

Soil and Water Conservation

Society is an international nonprofit

scientific and educational organization

serving as an advocate for the

conservation profession and for

science-based conservation policy.