SOIL CARBON CYCLING, TRACE GAS EMISSION, TILLAGE AND CROP RESIDUE MANAGEMENT
Location: Soil Management Research
Title: Greenhouse Gas Emission from Contrasting Management Scenarios in the Northern Corn Belt
Submitted to: Soil Science Society of America Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: May 4, 2009
Publication Date: March 1, 2010
Citation: Johnson, J.M., Archer, D.W., Barbour, N.W. 2010. Greenhouse Gas Emission from Contrasting Management Scenarios in the Northern Corn Belt. Soil Science Society of America Journal. 74(2):396-406.
Interpretive Summary: Carbon dioxide, methane and nitrous oxide are called greenhouse gases because they contribute to global warming. Agriculture is a source of these gases, so farming systems that release less of these gases and store more carbon in soil are desirable. Three systems were compared. The first treatment was intensively tilled every year, received high fertilizer inputs, and rotated with corn and soybean. In the second system, the soil was only tilled twice in four years, received fertilizer once in four years, and rotated with four crops (corn, soybean, wheat, and alfalfa). The third system differed from the second in that it was not fertilized. The release of carbon dioxide, methane and nitrous oxide was measured every other week for three years. The amount of gases released varied among crops, tillage and year. Very little methane was released. Most of the nitrous oxide was released in the very early spring as the soil thawed. This work provides information on the overall impact of management on greenhouse gas emission. This information benefits producers, scientists, and policy-maker by providing guidance toward developing agricultural systems that reduce global warming risks without sacrificing productivity or profitability. This work contributes to the USDA-ARS GRACE.net project.
Long-term cropping systems field plots were established in 2002 in west central Minnesota to compare tillage, rotation and fertilizer treatments and to identify and develop economically viable and environmentally sustainable farming systems. Greenhouse gas (GHG) emission was monitored in three scenarios: business as usual (BAU), maximum C sequestration (MAXC) and optimum greenhouse gas benefits (OGGB). The BAU scenario had conventional tillage (chisel or moldboard plow), and received high fertilizer inputs in a corn-soybean rotation. The MAXC and OGGB scenarios were strip tilled with a mole-knife in a corn-soybean-wheat/alfalfa-alfalfa rotation. The MAXC received high fertilizer inputs but OGGB scenario was unfertilized. Nitrous oxide (N2O), carbon dioxide (CO2) and methane (CH4) emissions were monitored using vented static chambers. Collateral information collected included weather data, soil temperature and volumetric soil moisture at time of sampling. Two collars were installed in each plot sampled. For corn (Zea mays L.) and soybean (Glycine max L. Merrill) row crops, one collar was positioned adjacent to the row and the second collar was in the inter-row. In wheat (Triticum aestivum L.) and alfalfa (Medicago sativa L), collars were positioned randomly with regard to plants. Plots were sampled every other week with additional episodic sampling. The greatest N2O flux occurred during spring thaw events with minor flux events corresponding N fertilizer application. Under these managements, the soil tended to be neutral to slight CH4 sink. [GRACE.net publication]