Submitted to: Transactions of the ASABE
Publication Type: Peer reviewed journal
Publication Acceptance Date: 11/15/2010
Publication Date: 2/16/2011
Citation: Way, T.R., Watts, D.B., Smith, K.E., Torbert III, H.A. 2011. Calculation of effective gas flux from soil following band application of manure or fertilizer. Transactions of the ASABE. 54(1):337-345. Interpretive Summary: Concerns about climate change have generated interest in evaluating impacts of land use practices on greenhouse gas emissions. In the U.S., the annual carbon dioxide equivalent emissions from agriculture are about 450 million metric tons of carbon dioxide. Another negative consequence of greenhouse gas emissions from soil is the detrimental impact on soil quality from the loss of nitrogen and carbon from soil. Band application of manure and fertilizer is a method of applying these materials in narrow bands, either on the soil surface or beneath the soil surface. Calculations of average gas fluxes emitted from a field area are more complex for band application than for broadcast application of manure or fertilizer. Gas flux chambers that are circular or rectangular, when viewed from above, are commonly used by researchers in determining emissions of greenhouse gases from soil. A method was developed for calculating average gas fluxes emitted from a field area to which manure or fertilizer has been applied in bands. The method is useful for both circular and rectangular flux chambers. This method is expected to be useful in quantifying greenhouse gas emissions from fields to which manure or fertilizer has been applied in bands, either on the soil surface or in subsurface bands.
Technical Abstract: Greenhouse gases are emitted following application of manure and nitrogen-containing fertilizers to soil. Manure and fertilizers are often applied in subsurface bands in the soil, or in bands on the soil surface. This article presents a method that has been developed for calculating the effective gas flux for a multiple-band area to which manure or fertilizer has been applied in bands. The method has been developed for circular and rectangular flux chambers. For example, when a circular flux chamber that is 254 mm inside diameter is used with a band width of 40 mm, a band spacing of 0.762 m, gas fluxes of 100 µmol m^-2 min^-1 from a chamber centered over a band and 50 µmol m^-2 min^-1 from a chamber on a control area to which no manure or fertilizer has been applied, the effective gas flux of the whole plot is calculated as 61.9 µmol m^-2 min^-1. In this example, if the 100 µmol m^-2 min^-1 flux in the chamber that was centered on the band was assumed to be the whole plot effective flux, the assumption would have overestimated the actual effective flux of 61.9 µmol m^-2 min^-1 by 62%. This method provides appropriate calculations of gas fluxes from whole plots to which manure and fertilizers have been band-applied.