ARS | Publication request: Tillage and wind effects on soil CO2 concentrations in muck soils

Submitted to: Soil and Tillage Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: February 8, 2008
Publication Date: June 1, 2008
Repository URL: http://hdl.handle.net/10113/21484
Citation: Reicosky, D.C., Gesch, R.W., Wagner, S.W., Gilbert, R.A., Wente, C.D., Morris, D.R. 2008. Tillage and wind effects on soil CO2 concentrations in muck soils. Soil and Tillage Research. 99:221-231.

Interpretive Summary: Rising atmospheric carbon dioxide (CO2 ) concentrations from agricultural activities has prompted the need to quantify greenhouse gas emissions to better understand carbon (C ) cycling and its role in environmental quality. This work determined the effect of no-tillage, deep plowing and wind speeds on the soil CO2 concentration in muck soils of the Florida Everglades. The soil CO2 concentration exhibited temporal dynamics independent of barometric pressure fluctuations. Loosening the soil resulted in a very rapid decline in CO2 concentration as a result of "wind-induced" gas exchange from the soil surface. Higher wind speeds during mid-day resulted in a more rapid loss of CO2 from the deep plowed than from the no till (NT) plots. The subtle trend in the NT plots was similar, but lower in magnitude. Tillage-induced change in soil air permeability enabled wind speed to affect the gas exchange and soil CO2 concentration at 30 cm, literally drawing the CO2 out of the soil resulting in a rapid decline in the CO2 concentration. Wind and associated aerodynamic pressure fluctuations have a large effect on gas exchange from soils, especially these tilled muck soils with very low bulk densities and high soil air permeability following tillage. This information will assist scientists, engineers and policy makers in developing improved tillage methods to minimize the gaseous loss and to improve soil carbon management. Farmers can develop and utilize new management techniques for enhancing soil carbon by increasing the quantity and quality of crop residues and by changing the type and intensity of tillage. Incorporating C storage in conservation planning demonstrates concern for our global resources and presents a positive role for soil C policies and our future quality of life.

Technical Abstract: Rising atmospheric carbon dioxide (CO2 ) concentrations from agricultural activities has prompted the need to quantify greenhouse gas emissions to better understand carbon (C ) cycling and its role in environmental quality. The specific objective of this work was to determine the effect of no-tillage, deep plowing and wind speeds on the soil CO2 concentration in muck soils of the Florida Everglades. Miniature infrared gas analyzers were installed at 30 cm and recorded every 15 min. in muck soil plowed with the Harrell Switch Plow (HSP) to 42 cm and in soil Not Tilled (NT) in the last nine months. The soil CO2 concentration exhibited temporal dynamics independent of barometric pressure fluctuations. Loosening the soil resulted in a very rapid decline in CO2 concentration as a result of "wind-induced" gas exchange from the soil surface. Higher wind speeds during mid-day resulted in a more rapid loss of CO2 from the HSP than from the NT plots. The subtle trend in the NT plots was similar, but lower in magnitude. Tillage-induced change in soil air permeability enabled wind speed to affect the gas exchange and soil CO2 concentration at 30 cm, literally drawing the CO2 out of the soil resulting in a rapid decline in the CO2 concentration. At the end of the study, CO2 concentrations in the NT plots averaged about 3.3% while the average concentration in the plowed plots was about 1.4%. Wind and associated aerodynamic pressure fluctuations have a large effect on gas exchange from soils, especially these tilled muck soils with very low bulk densities and high soil air permeability following tillage.