SEQ CHAPTER \h \r 1Land application of poultry litter provides essential nutrients for
crop production, but nitrogen (N) losses to the atmosphere can be detrimental
to the environment. A multi-season study
was conducted to quantify ammonia (NH3) and nitrous
oxide (N2O)
volatilization rates from surface applied poultry litter under no-till (NT) and
paraplowed (PP) conservation tillage managements. Litter was applied in the winter and summer
at rates of 100 and 200 kg N ha-1,
respectively. Evaluation of
volatilization rates were determined
using gas concentrations and the flux-gradient gas transport technique and the
momentum balance transport coefficient.
Nitrous oxide fluxes ranged from 4.4 to 7.6% of total N applied. Total N2O losses
were about 22% larger during the summer than winter study but a larger
percentage of applied N was lost during the winter. Nitrous oxide losses during the winter were
8.1 and 7.2 kg ha-1 for the NT and PP treatments, respectively. Total losses during the summer were 11.2 and
7.4 kg N2O ha-1 for the NT and PP treatments,
respectively. The relatively large
losses during the winter indicate the importance of year-round measurements for
accurate N2O emission
estimates. The losses found in this
study were substantially greater than the 1.25% emission factor used by the
Intergovernmental Panel on Climate Change to estimate global emissions and may
have been related to the reduced tillage management practices used in these
studies. Ammonia fluxes ranged
from 3.3 to 24% of the total N applied during the winter and summer,
respectively. Ammonia volatilization was rapid immediately after
litter application and stopped within 7 to 8 days. Precipitation of 17 mm essentially halted
volatilization, probably by transporting litter N into the soil matrix. There was no differences in total NH3
volatilization between no-till and paraplowed treatments.