Nitrous oxide emissions from a tree-based intercropping system compared to a conventional monoculture in southern Ontario, Canada

Methods are currently being sought that reduce Nitrous Oxide (N 2O), a greenhouse gas, from agricultural systems. The first objective of this study was to determine if a Tree-Based Intercropping (TBI) system could potentially limit N2O flux compared to a conventional monoculture. The study was undertaken at the Guelph Agroforestry Research Station (GARS) using the chamber method to take N2O measurements. No significant difference was found in mean N2O emissions between the TBI system (7.5 g ha-1 day-1) and conventional monoculture (10.7 g ha-1 day-1) between summer 2007 through summer 2008.;The second objective of this study was to determine the relationship between earthworm (Lumbricus terrestris L.) density, gravimetric soil water content (thetag) and N2O flux in a controlled greenhouse experiment based on population densities (90 to 270 individuals m-2) found at GARS from 1997 to 1998. A preliminary experiment conducted at 3-times the normal densities of earthworms found at GARS revealed a significant relationship between earthworm density, thetag and N2O emissions, with the highest mean emissions being 43.5 g ha-1 day-1 at 30 earthworms per 0.033 m 2 at 35% thetag. However, a second experiment, based on the density of earthworms at GARS, found no significant difference in N2O emissions (5.49 to 6.99 g ha-1 day -1) relative to earthworm density at 31% thetag.