How do I use COMET-VR?

1. Go to the Web site: 

http://www.cometvr.colostate.edu/

2. Select the “COMET-VR Tool” from the tab on 

the right.

3. Answer six step-by-step questions about your 

site:

State

County

Parcel Size

Soil

Rotation

Tillage

4. Select: 

How does COMET-VR work?

COMET-VR uses the Century soil carbon model to 

provide estimated soil carbon differences resulting 

from changes in land management. Century is 

a generalized ecosystem model which simulates 

carbon (e.g., biomass), nitrogen, and other nutrient 

dynamics. The model simulates management 

impacts on soil carbon, as well as the effects of 

land use changes between cropland, grassland, 

and forest. 

Producers using no-till, conservation tillage, 

improved grazing management, or other 

conservation practices, provide storage for 

carbon benefiting their farms, ranches, and 

the environment. COMET-VR allows them to 

document their 

carbon changes 

and evaluate the 

impact of their 

management 

activities on soil 

carbon. 

Once farmers or 

ranchers have 

run COMET-VR 

and obtained 

a soil carbon 

sequestration 

value, they can 

register those 

values as carbon 

credits under 

the Voluntary Emission Reduction Registration 

Program (Section 1605(b) of the 1992 Energy 

Policy Act, http://www.usda.gov/oce/global_

change/gg_reporting.htm). Through this program, 

carbon credits may become a traded commodity.

What is COMET-VR?

COMET-VR is an online management tool 

that provides a simple and reliable method for 

estimating changes in soil carbon sequestration, 

fuel, and fertilizer use resulting from changes in 

land management.

What is Carbon Sequestration?

Storing, or “sequestering,” carbon involves 

increasing the organic matter in soils (“humus”) 

and in vegetation. Sequestering carbon helps 

reduce the amount of carbon dioxide (CO2) in the 

atmosphere. 

Why is Carbon Sequestration 

Important?

Carbon, in the form of CO2 , when released to the 

atmosphere, traps heat within the atmosphere. It 

raises the temperature of the air and contributes 

to what is known as the “greenhouse effect.” 

What Benefits Can I Get from 

Sequestering Carbon?

Sequestering carbon improves both soil and 

air quality and can help mitigate atmospheric 

change. Stored soil carbon could become a 

valuable traded commodity as we move toward 

an environmentally conscientious, market-based 

economy.
Conservation Activities

Many conservation activities can directly or 

indirectly address atmospheric change and 

greenhouse gas issues related to agricultural 

operations. Some may be eligible for payments 

under USDA conservation programs such as the 

Environmental Quality Incentives Program, or the 

Conservation Security Program. 

Resource Benefits

Conservation practices and management activities 

can:

•	 Reduce emissions of greenhouse gases 

(carbon dioxide, methane, and nitrous oxide) 

from agricultural operations, feedlots, and 

equipment;

•	 Increase soil carbon in cropland and grazing 

land;

•	 Increase forest carbon stocks; and

•	 Provide greenhouse gas offsets through 

the use of agriculture residues and manure 

management.

Well-managed rangeland can help sequester carbon 

in the soil.

Conservation Activities that 

Sequester Carbon and Reduce 

Greenhouse Gases

•	 Tillage programs, such as no-till, and 

machinery that combine operations and 

reduce the number of trips across a field

•	 Use of bio-based fuel 

•	 Nutrient management to reduce nitrous 

oxide emissions from agricultural fields

•	 Feed management to reduce methane 

generation in ruminant animals

•	 Grazing management to sequester carbon in 

range and pasture soils

•	 Manure management and/or anaerobic 

digester technology to capture methane for 

use as an energy supply

•	 Participation in carbon trading and/or 

voluntary reporting of greenhouse gas 

programs

•	 Agricultural residues to produce bio-based 

products

•	 Residue management, cover crops, and 

reduced fallow periods to sequester carbon 

in soils

COMET-VR was developed in cooperation 

with Colorado State University, NREL.

NRCS is an equal opportunity provider and employer.

WNTSC 03/07

COMET-VR

The CarbOn Management 

Evaluation Tool – Voluntary 

Reporting (COMET-VR)

Learn more about air quality and 

atmospheric change by visiting 

the following NRCS Web site:

www.airquality.nrcs.usda.gov/

Helping Farmers 

and Ranchers 

Estimate Soil Carbon 

Sequestration

Program Aid 1926 Helping People Help the Land