Book: Cropland Helps Control CO2 and Ease Greenhouse Effect

A new book by USDA and university scientists sheds fresh light on agriculture's potential to help offset the projected greenhouse effect—global warming from increasing carbon dioxide and other greenhouse gases in Earth's atmosphere.

The authors, experts in soil science, conclude that better farming practices could sequester—remove—much more carbon dioxide from the atmosphere than they now do. Instead, more carbon would be stashed in the soil to benefit crops and the environment.

The Potential of U.S. Cropland to Sequester Carbon and Mitigate the Greenhouse Effect (128 pages, Ann Arbor Press, Chelsea, Mich.) was written by four soil science experts. They are J. M. Kimble of USDA's Natural Resources Conservation Service, R. F. Follett of USDA's Agricultural Research Service, R. Lal at Ohio State University at Columbus, and C.V. Cole at Colorado State University at Fort Collins.

Crop plants remove carbon dioxide from the atmosphere by photosynthesis as they grow. After harvest, leftover stalks and other residue that get incorporated into the soil decay to become organic carbon. Farming methods that increase soil carbon, such as conservation tillage, result in less carbon dioxide being returned to the atmosphere as a greenhouse gas than with previous tillage methods.

Conservation tillage systems are predicted to sequester around 500 pounds per acre per year more soil organic carbon than do plow tillage systems, according to Follett, with ARS' Soil Plant Nutrient Research Unit in Fort Collins, Colo. Soil erosion from U.S. cropland soils was assessed to result in the release of about 16 million tons of carbon a year to the atmosphere as carbon dioxide.

Raising soil organic carbon levels could have many spinoff benefits: higher crop yields over the long term, increased soil quality, less erosion, better soil tilth (an indicator of soil health), higher farm income and improved water quality.

ARS is USDA's chief scientific agency.

Scientific contact: Ronald F. Follett, ARS Soil Plant Nutrient Research Unit, Fort Collins, Colo., phone (970) 490-8220, fax (970) 490-8213, rfollett@lamar.colostate.edu; John M. Kimble, NRCS National Soil Survey Center, Lincoln, Neb., phone (402) 437-5376, fax (402) 437-5336, jkimble@gw.nssc.nrcs.usda.gov.