Title: Changes in Soil Organic Carbon of Crop Rotations in the Northern Corn Belt Authors
Submitted to: Meeting Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: August 8, 2007
Publication Date: November 4, 2007
Citation: Pikul Jr, J.L., Schumacher, T.E., Vigil, M.F., Riedell, W.E. Changes in Soil Organic Carbon of Crop Rotations in the Northern Corn Belt. In Annual Meetings Abstracts (CD-ROM). ASA, CSSA, SSSA, Madison, WI. 2007. Technical Abstract: Diversified crop rotation may reduce fertilizer nitrogen (N) input for corn (Zea mays L.) and increase soil organic carbon (SOC) storage. Objectives were to determine effect of rotation and N on soil C sequestration. The experiment, started in 1990, was on a Barnes sandy clay loam near Brookings, SD. Since 1996, primary tillage was chisel plow on all rotations. Prior to 1996, moldboard plow was used. Crop rotations were: continuous corn (CC), corn-soybean [Glycine max (L.) Merr.] (CS), and a four-year rotation of corn-soybean-wheat (Triticum aestivum L.) companion seeded with alfalfa (Medicago sativa L.)-alfalfa hay (CSWA). During a four-year cycle, there was 35 percent less tillage used on CSWA compared to CC. Non-cropped treatments included warm, cool, and a mix of warm and cool season perennial grasses. Nitrogen treatments for corn were: corn fertilized for a grain yield of 8.5 Mg/ha (highN), 5.3 Mg/ha (midN), and no N fertilizer (noN). Soil organic C (0 to 15 cm) under grass increased 6 Mg C/ha from 1996 to 2006. Continuous corn under highN returned about 2.3 times as much above-ground plant C to the soil as CSWA. Rate of loss of organic C under CC has been nearly the same as the rate of C return from plant materials: there was a loss of SOC (-0.07 Mg C/ha) from the top 15 cm of soil under CC from 1996 to 2006. Under CSWA all N treatments gained SOC in the top 15 cm; average increase was 2.4 Mg C/ha. Corn yield under CSWA with no fertilizer N was 91% of the yield attained under CC fertilized at highN. Increased SOC under CSWA may be related to reduction of tillage and inclusion of alfalfa in the four-year crop rotation.