ARS | Publication request: Effects of Cover Crop Systems on Soil Physical Properties and Carbon/Nitrogen Sequestration in Coastal Plain Soils Under Conservation Tillage

Submitted to: Journal of Soil and Water Conservation Society
Publication Type: Abstract Only
Publication Acceptance Date: February 1, 2007
Publication Date: July 21, 2007
Citation: Hubbard, R.K., Strickland, T.C., Phatak, S.C., Scholberg 2007. Effects of Cover Crop Systems on Soil Physical Properties and Carbon/Nitrogen Sequestration in Coastal Plain Soils Under Conservation Tillage [abstract]. Journal of Soil and Water Conservation Society July 21-25, 2007, Tampa, Florida.

Technical Abstract: Conservation practices are needed to prevent erosion and preserve soil and water quality. Conservation tillage has been found to be an effective environmental practice. Uncertainty exists concerning the impact of cover crops with conservation tillage on the total agricultural environment. A study conducted from 2002 – 2005 by the University of Georgia, University of Florida, and USDA-ARS, assessed the effects of cover crops on soil physical properties and C/N sequestration in coastal plain soils. The cropping systems were (1) sunnhemp (Crotalaria juncea L.), crimson clover (Trifolium incarnatum L.), sweet corn (Zea mays L.); (2) sunnhemp, fallow, sweet corn; (3) fallow, crimson clover, sweet corn; (4) fallow, fallow, sweet corn; or (5) fallow, fallow, fallow. Soil physical property measurements were made on minimally disturbed cores collected from the top 7.6 cm of soil of each plot three times annually using an impact type sampler. Physical property measurements included bulk density (BD), saturated hydraulic conductivity (HC), and soil moisture retention (MR). Microbial biomass carbon, available carbon, soil nitrogen and soil carbon were determined from samples of the top 2.5 cm of soil collected quarterly. Results showed cover crop differences in soil physical properties and C/N sequestration. Rotations with sunnhemp as crop one had lower BD, greater HC, and greater total C and N than the other cropping systems. Inclusion of sunnhemp, which produces large quantities of biomass, as a cover crop in rotations on coastal plain soils benefited the soil by increasing hydraulic conductivity (greater water infiltration at the surface and less runoff), decreasing bulk density, and increasing C/N sequestration. The study showed the significant effects that cover crop type in agricultural systems has on organic matter accumulation including positive effects on soil physical properties important to crop production. Results from this and similar small-scale studies will be used to establish appropriate ranges for model parameter calibrations when comparing conservation to conventional farming practices.