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Title: IMPACT OF NITROGEN FERTILIZATION AND CROPPING SYSTEM ON CARBON SEQUESTRATION IN MID-WESTERN CORN BELT MOLLISOLS

Author
item RUSSELL, ANN - IOWA STATE UNIVERSITY
item Laird, David
item Parkin, Timothy
item MALLARINO, ANTONIO - IOWA STATE UNIVERSITY

Submitted to: Soil Science Society of America Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/30/2004
Publication Date: 3/5/2005
Citation: Russell, A.R., Laird, D.A., Parkin, T.B., Mallarino, A. 2005. Impact of nitrogen fertilization and cropping system on carbon sequestration in mid-western corn belt mollisols. Soil Science Society of America Journal. 69(2):413-422.

Interpretive Summary: Global warming due to the accumulation of greenhouse gasses (mostly carbon dioxide and methane) in the atmosphere is a serious concern. One strategy for slowing the rate of greenhouse gas accumulation in the atmosphere is to use plants to remove carbon dioxide from the atmosphere and then store the carbon in the soil as soil organic matter. This strategy has the added benefit of improving soil quality. For this strategy to be effective, accurate information is needed on the impact of agricultural management practices on levels of soil organic carbon. We have determined that nitrogen fertilization has little or no impact on the accumulation of soil organic carbon for row-crop production systems under conventional management. We also demonstrated that cropping systems that include meadow crops (e.g., alfalfa, red clover) in rotations with corn and/or soybeans accumulate significant amounts of soil organic carbon. By contrast, continuous corn and corn-soybean rotations under conventional management have either stable levels of, or are loosing, soil organic carbon. This information will be used by regulatory and action agencies to help design national policies for addressing the problem of global warming.

Technical Abstract: Growing interest in the potential for agricultural soils to provide a sink for atmospheric C has prompted studies of the effects of management on soil organic carbon (C) (SOC) sequestration. We analyzed the impact on SOC of four nitrogen (N)-fertilization rates (0, 90, 180, and 270) and four cropping systems: continuous corn (CC) (Zea mays L.); corn-soybean [Glycine max (L.) Merr.] (CS); corn-corn-oats(Avena sativa L.)-meadow (CCOM) and corn-oats-meadow-meadow (COMM). Meadow included a mixture of alfalfa (Medicao sativa L.) and red clover (Trifolium pratense L.). Soils were sampled in years 23 and 48 of two experiments located in northeast and north-central Iowa, respectively, which were conducted using a replicated split-plot design under conventional tillage. A native prairie was sampled to provide a reference point at an undisturbed area. The native prairie site had the same soil series as one of the experimental sites, but was located 50 km north of the site. Cropping systems that contained meadow had the highest SOC stocks, whereas the CS system generally had the lowest SOC stocks. Concentrations of SOC increased significantly over the last 12 years in only two of nine systems for which historical data were available, the fertilized CC and COMM systems at one site. Several indices of soil quality, including particulate organic C and resistant C concentrations, were influenced by cropping system, with CS