USING AGRICULTURAL AND INDUSTRIAL BYPRODUCTS TO IMPROVE CROP PRODUCTION SYSTEMS AND ENVIRONMENTAL QUALITY
Location: National Soil Dynamics Laboratory
Title: Soil carbon dioxide fluxes in conventional and conservation tillage corn production systems receiving poultry litter and inorganic fertilizer
Submitted to: Journal of Sustainable Agriculture
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: January 30, 2012
Publication Date: October 19, 2012
Citation: Nyakatawa, E.Z., Mays, D.A., Way, T.R., Watts, D.B., Torbert III, H.A., Smith, D.R. 2012. Soil carbon dioxide fluxes in conventional and conservation tillage corn production systems receiving poultry litter and inorganic fertilizer. Journal of Sustainable Agriculture. 36(8):873-892.
Interpretive Summary: Agricultural soil is a source of greenhouse gases such as methane (CH4), nitrous oxide (N2O), and carbon dioxide (CO2). Poultry litter is a mixture of poultry manure and a bedding material, such as pine shavings. Manure, including poultry litter, is a useful fertilizer, but has been shown to emit greenhouse gases into the atmosphere. Poultry litter is commonly spread on agricultural fields using a broadcast application method that places the litter on the soil surface. Subsurface band application is a new method for applying poultry litter in shallow trenches in the soil and covering the litter with a two-inch thick layer of soil. Corn was grown in a field experiment on a silt loam soil in north Alabama. The two types of fertilizer used were poultry litter and ammonium nitrate fertilizer, which is a conventional commercially-available fertilizer. The three methods for applying fertilizer to the soil were broadcast application on the soil surface, subsurface band application, and soil incorporation in which the fertilizer was tilled into the top few inches of soil. The two types of crop management systems used were conventional tillage, in which the soil was tilled before planting the corn, and no-till, in which a wheat cover crop was grown and the soil was not tilled before planting. Emissions of carbon dioxide from the soil surface were measured. Although using poultry litter as a source of nitrogen fertilizer resulted in higher soil emissions of carbon dioxide compared to inorganic ammonium nitrate fertilizer in the spring, fall, and winter, there were no significant differences between poultry litter and ammonium nitrate fertilizer in terms of cumulative carbon dioxide emissions. If poultry litter is applied to soil when the soil is not too wet, land application of poultry litter using surface broadcast or subsurface band application methods does not increase the emission of carbon dioxide to the atmosphere compared to using inorganic fertilizer on this silt loam soil in the short-term.
Soil management practices for increasing agricultural production can alter the natural balance at the soil-plant-atmosphere ecosystem interface. In the long-term, this can significantly affect the environment. This study investigated soil CO2 emissions in conventional tillage (CT) and no-tillage (NT) corn production systems receiving poultry litter (PL) and ammonium nitrate (AN) fertilizers on a silt loam soil in the Tennessee Valley Region of north Alabama in 2008 and 2009. Soil CO2 fluxes were not significantly affected by tillage system in spring, fall, and winter. However, in summer, soil CO2 flux in the CT plots (9.5 kg CO2 ha-1 day-1) was 94% greater than that in the NT plots (4.9 kg CO2 ha-1 day-1). Soil CO2 fluxes for both tillage treatments were lowest in the fall, as the CT plots then had a mean soil CO2 emission of 0.8 kg CO2 ha-1 day-1. The NT plots and a grass fallow system were sinks of CO2 with fluxes of -0.6 and -1.0 kg CO2 ha-1 day-1, respectively. The cumulative soil CO2 flux averaged over the seasons of the study period for the NT plots (14.8 kg CO2 ha-1 day-1) was 38% less than that of the CT plots (19.8 kg CO2 ha-1 day-1). Grass fallow plots were net sinks of CO2 with a cumulative CO2 mean flux of -1.6 kg CO2 ha-1 day-1. Although using PL as a source of N resulted in higher soil emissions of CO2 compared to inorganic AN fertilizer in the spring, fall, and winter, there were no significant differences in cumulative CO2 fluxes between the two sources of N during the study period. If PL application is timed to avoid application under high soil moisture conditions, land application of PL using surface broadcast or subsurface band application methods does not increase the emission of CO2 to the atmosphere compared to using inorganic fertilizer on this silt loam soil in the short-term.