U.S. Department of Agriculture: Agricultural Research Service, Lincoln, Nebraska
Date of this Version
2002
Citation
Great Plains Soil Fertility Conference, March 5-6, 2002
Abstract
Soil organic carbon (SOC) in the surface soils has increased when summer fallow is reduced or eliminated in the central Great Plains. We evaluated the effect of no-till cropping systems of WF, wheat-com-fallow (WCF), wheat-corn-millet-fallow (WCMF), opportunity cropping (OPP), and native grass species (G) on particulate organic matter (POM-C) and mineral associated C in the silt and clay fractions. Soil organic carbon (SOC) has increased with increasing cropping intensity after 12 years, of no-till management. Particulate organic matter C accounted for 38 to 52 % of the total SOC in the 0-2.5 cm and 24 to 48 % of the total SOC in the 2.5-5 cm depth depending on cropping intensity. In the 5-10 cm depth, POM-C accounted for 22-35 % of the total SOC depending on cropping intensity. In the 10-20 cm depth, however, POM-C accounted for only 0 to 12 % of the total SOC depending on cropping intensity. In all depth increments however, G had the highest POM-C followed by OPP. Overall, the increase in total SOC in surface soils with increasing cropping intensity was due to increased C in the POM-C fraction.