| Laboratory and field studies were conducted to examine the effect of different amendments on the transformation of nitrogen (N) in soil and the emission of N2O-N and CO2-C. Amendments included alfalfa (Medicago sativa), liquid cattle manure and ammonium nitrate synthetic fertilizer (AN) applied at rates typical for a dairy farm in Eastern Ontario. The highest levels of N transformations, N2O-N and CO 2-C emissions occurred in plots amended with alfalfa, followed by manure, AN and control. With lower C:N ratios in the organic amendments, these results indicate the importance of carbon (C) in N cycling. Transformations and emissions of gases occurred very rapidly after application of amendments with more than half the total N2O-N and CO2-C emission occurring within the first 10 days of the field experiment. Quantities of inorganic N were highest in the plots amended with AN, followed by manure, alfalfa and control. These results have practical implications for the type of amendments and the timing of application needed to improve soil N availability while reducing greenhouse gas emissions. |
