TRACE GAS EXCHANGES IN MIDWEST CROPPING SYSTEMS
Location: Soil, Water, and Air Resources Research Unit
Title: Greenhouse gases emission from two soils under N fertilizer and swine slurry
Research conducted cooperatively with:
| Agcert International, Llc|
Submitted to: Journal of Environmental Quality
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: April 24, 2007
Publication Date: June 24, 2008
Citation: Jarecki, M.K., Parkin, T.B., Chan, A.S., Hatfield, J.L., Meek, D.W., Jones, R. 2008. Greenhouse gases emission from two soils under N fertilizer and swine slurry. Journal of Environmental Quality. 37:1432-1438.
Interpretive Summary: Fertilizer applications to agricultural soils are implicated in the production of the greenhouse gases, nitrous oxide (N2O) and methane (CH4). This study was performed to investigate the relationship between fertilizer type (commercial fertilizer vs. swine manure) and soil type (sandy vs. clayey) on N2O and CH4 emissions. We observed that in the sandy soil, there was no difference in N2O emissions in the swine manure or commercial fertilizer treatments. However, in the clay soil N2O emissions were greater from the swine manure treatment than the commercial fertilizer treatment. Overall, the sandy soil had greater N2O emissions than the clay soil, and we speculate that this difference was due to the fact that the clay soils bind the swine manure-nitrogen (N) and fertilizer-N more tightly, making this N less susceptible to N2O losses. No soil or fertilizer effects were found for CH4 emissions. This information is useful to entities engaged in carbon credit trading, and may be useful to policy makers in assessing agriculture’s role in the mitigation of atmospheric greenhouse gas concentrations.
The study was conducted on two soils to: i) compare nitrous oxide (N2O), carbon dioxide (CO2) and methane (CH4) fluxes from swine slurry and fertilizer nitrogen (N), ii) determine N loses through N2O emission, and iii) assess global warming potential (GWP) of treatments. The soils used were loamy sand and clay which had 790 and 216 g kg-1 of sand and 10.6 and 26.5 cmolc kg-1 of cation exchange capacity (CEC), respectively. The pots, containing 12 kg of soil without vegetation, were incubated for 8 weeks. The treatments were: i) control (no N), ii) fertilizer N as a urea-ammonium nitrate (UAN) solution, and iii) swine slurry, injected at the 5 cm depth at the rate of 200 kg N ha-1. Cumulative emissions of N2O, CO2 and CH4 were higher from sand than from clay. Fertilizer N and swine slurry enhanced N2O emission on the sand with no difference between N sources. For the clay, the N2O emissions ranked slurry > fertilizer N > control. Enhanced CO2 and CH4 fluxes were observed from slurry in both soils. The N2O-N losses from fertilizer amounted to 3.3 and 0.2% from the sandy and clayey soils, respectively. The N2O-N losses from the slurry accounted for 2.7 and 1.8 % of applied N for sand and clay, respectively. N2O losses from the sand were higher than the Intergovernmental Panel on Climate Change (IPCC) emission factor of 1.25%. This study showed that sand with low CEC emitted more GHGs than clay with high CEC. The N2O production from fertilized N was the main source of GWP (59%) on sandy soil. The N2O emission from the slurry N largely contributed to GWP on sandy and clayey soils (41 and 36%, respectively).