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United States Department of Agriculture

Agricultural Research Service

Research Project: Improved Soil Managment Practices for Tilled Summer Fallow in the Pacific Northwest

Location: Soil and Water Conservation Research

Title: Predicted soil management and climate change effects on SOC in South Carolina

Author
item Nash, Patrick
item Gollany, Hero
item Novak, Jeffrey - Jeff
item Bauer, Philip - Phil
item Hunt, Patrick
item Karlen, Douglas - Doug

Submitted to: Agronomy Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: 7/28/2015
Publication Date: N/A
Citation: N/A

Interpretive Summary: Extensive use of inversion tillage has contributed to the loss of soil organic carbon (SOC) and degraded soil health in the southeast USA. Our objective was to predict changes in SOC in a sandy soil in Florence, SC under several crop rotations of corn-cotton, corn-soybean, sorghum-soybean, sorghum-cotton, or corn-soybean with rye, and corn-soybean or sorghum-soybean with double-cropped winter wheat, and tillage practices (conventional and conservation tillage), predicted changes in precipitation and air temperature under expected responses of climate change, and crop yield growth rates. A carbon model, CQESTR, was fitted with 12 years of crop production and SOC data and used to predict changes in SOC through 2033. The model predicted change in SOC at the 6‚ÄĚsoil depth was significantly correlated with annualized biomass inputs and ranged from -1.87 lb/ac with sorghum-cotton to 3.88 lb/ac with corn-soybean with rye over the period of 2014-2033. Conservation tillage was predicted to increase SOC content 4 to 17% under six of eight crop rotations. Climate change was predicted to change SOC by -0.8 to -6.6%, compared to 6 to 16% when current crop yield growth rates were factored into the model simulations. High residue producing crop rotations such as corn and/or winter crops in combination with conservation tillage are likely the best management practices to maximize soil C sequestration; however, conservation practices with the ability to increase SOC deeper in the soil profile may be necessary for long-term SOC accumulation.

Technical Abstract: Extensive use of inversion tillage has contributed to the loss of soil organic carbon (SOC) and degraded soil health in the southeast U.S.A. Our objective was to predict changes in SOC in a Norfolk loamy sand in Florence, SC under several crop rotations (corn (Zea mays L.)-cotton (Gossypium ssp.), C-CT; corn-soybean (Glycine max (L.) Merr.), C-SB); sorghum (Sorghum bicolor (L.) Moench)-soybean, SG-SB; sorghum-cotton, SG-CT, C-CT or C-SB with Rye (Secale cereale L.); and C-SB or SG-SB with double-cropped winter wheat (Triticum aestivum L.), WW)), and tillage practices (conventional (CvT) and conservation (CnT) tillage), predicted changes in precipitation and air temperature under expected responses of climate change, and crop yield growth rates. CQESTR, a process-based C model, was fitted with 12 years of crop production and SOC data (2002-2013) and then used to predict changes in SOC through 2033. The model predicted change in SOC at the 0-15 cm soil depth was significantly correlated (r = 0.98) with annualized biomass inputs and ranged from -4.19 Mg C/ha with SG-CT to 8.69 Mg C/ha with C-SB w/Rye over the period of 2014-2033. Conservation tillage was predicted to increase SOC content 4 to 17% under six of eight crop rotations. Climate change was predicted to change SOC by -0.8 to -6.6%, compared to 6 to 16% when current crop yield growth rates were factored into the model simulations. High residue producing crop rotations such as corn and/or winter crops in combination with CnT are likely the best management practices to maximize soil C sequestration; however, conservation practices with the ability to increase SOC deeper in the soil profile may be necessary for long-term SOC accumulation.

Last Modified: 09/25/2017
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