Influence of Tillage Practices on Subsurface Nitrogen Emissions
from Agricultural Soils
Jennifer Roper1, David Burton1, Ali Madani2, Glenn Stratton1
1
Department of Environmental Sciences, Nova Scotia Agricultural College, 21 Cox
Road, Truro, Nova Scotia, Canada, B2N 5E3; 2Department of Engineering, Nova Scotia
Agricultural College, 39 Cox Road, Truro, Nova Scotia, Canada, B2N 5E3
The desire to increase the sustainability of agriculture practices in Canada has resulted in
the identification and promotion of suites of “beneficial management practices”. One of
these practices is the no-tillage production system, where crops are direct seeded without
the use of conventional tillage practices for seedbed preparation. No-tillage systems
result in increased soil carbon (C) storage. In sub-humid ecosystems the potential of
elevated nitrous oxide (N2O) emissions from no-tillage methods may offset soil C
storage. Therefore, assessing the suitability of no-tillage systems requires an
understanding of the potential impacts on surrounding air and water resources. To
understand the potential impacts of tillage on nitrogen (N) dynamics in the soil profile,
the soil profile must be considered as a three dimensional, heterogeneous system.
Pathways of loss include surface loss of N2O, as well as losses of dissolved NO3- and
N2O exported in tile drainage water and water moving to groundwater. Therefore, a more
complete assessment of N2O production in agricultural systems must account for the
emissions resulting from loss of dissolved N2O in agricultural drainage waters and N2O
concentrations located at various depths of the soil profile. This study examined changes
in C, NO3- and water distribution under a no-tillage system and the resulting differences
in the stability of NO3- and accumulation of N2O in the soil profile, and loss of NO3- and
N2O in tile drainage water. Winter accumulation of N2O in the soil profile was followed
by late winter increased dissolved N2O emissions in drainage water. Greater N2O
emissions were observed under no-tillage management as a result of greater volumes of
drainage water.