N2O and CO2 Emissions from Bare Soil: Effect of Fertilizer Management

The paper presents the results of a laboratory experiment focused on the assessment of the effect of different methods of application of ammonium nitrate (TD—top dressing and DP—deep placement) on N2O and CO2 emissions from soil without crop cover. Nitrogen application increased soil N2O–N fluxes by 24.3–46.4%, compared to untreated soil (NIL). N2O–N emissions from TD treatment were higher by 12.7%, compared to DP treatment. Soil CO2–C fluxes from DP treatment were significantly higher by 17.2%, compared to those from NIL treatment. Nonetheless, the differences between soil CO2–C fluxes from DP and TD treatments, as well as from TD and NIL treatments, were of no statistical significance. The cumulative greenhouse gas (GHG) emissions (a sum of cumulative soil emissions of CO2–C and N2O–N after conversion to the equivalent of CO2–C) from both N-fertilized soils were similar, and higher by 20% than from untreated soil. The obtained data show that the effect of reduction of N2O–N soil emissions gained by deep placement of nitrogen fertilizer was completely lost through an increase in CO2–C emissions from the soil. This suggests that deep placement of nitrogen fertilizers in sandy soil without crop cover might not lead to a mitigation of soil GHG emissions.