Soil Carbon, Nitrogen Use, And Water Use Affected By Rotation In The Northern Corn Belt

Authors

Joseph L. Pikul Jr., USDA-ARSFollow
Thomas E. Schumacher, South Dakota State University
Merle Vigil, USDA-ARS
Walter E. Riedell, USDA-ARS

Date of this Version

2002

Citation

Great Plains Soil Fertility Conference, March 5-6, 2002

Abstract

Diversified crop rotation may improve production efficiency, reduce fertilizer nitrogen (N) requirements for com (Zea mays L.) and increase soil carbon (C) storage. Objectives were to determine effect of rotation and fertilizer N on soil C sequestration, water use, and N use. An experiment was started in 1990 on a Barnes clay loam (fine-loamy, mixed, superactive, frigid Calcic Hapludoll) near Brookings, South Dakota. Primary tillage on all rotations was with a chisel plow. Rotations were continuous com (CC), com-soybean [Glycine max (L.) Merr.] (CS) and a 4-year rotation of corn-soybean-wheat (Triticum aestivum L.) companion seeded with alfalfa (Medicago sativa L.)-alfalfa hay (CSWA). Additional treatments included plots of perennial warm season, cool season, and mixtures of warm and cool season grasses. N treatments for com were: com fertilized for a grain yield of 8.5 Mg ha-¹ (high N), 5.3 Mg ha^-1 (midN), and no N fertilizer (noN). Average com grain yield (1996-2001) was not different among rotations at 7.1 Mg ha^-1 under highN. Com yield differences among rotations increased with decreased fertilizer N. Average (1996-2001) com yield with noN fertilizer were 7.3 Mg ha^-1 under CSWA, 6.1 Mg ha-1 under CS, and 3.8 Mg ha^{- l} under CC. Rotation did not improve N use efficiency (NUE) or water use efficiency (WUE) under highN. With midN, NUE and WUE was about 40% greater under CSWA compared with CC. Plant carbon return depended on rotation and N. In the past 10 years, total C returned from above ground biomass were 29.8 Mg ha-I under CC with highN and 12.8 Mg ha^{- l} under CSWA with noN. Soil C in the top 15 cm significantly increased (0.7 g kg^{- l}) with perennial grass cover but decreased (1.7 g kg^{- l}) under CC, CS, and CSWA. C/N ratio significantly narrowed (-0.75) with CSWA and widened (0.72) under grass. Diversified rotations have potential to increase N use efficiency and reduce fertilizer N input for com. However, within a com production system using conventional tillage and producing (averaged across rotation and N treatment) about 6.2 Mg ha^{- l} com grain per year, we found no gain in soil C after 10 years regardless of rotation.