Nitrous Oxide Emissions from Tomatoes Grown on a Sandy Loam Soil.

The greenhouse effect is currently accepted as the driving factor behind global climate change.  This effect is attributed to anthropogenic activities that increase concentrations of greenhouse gases (GHG) such as carbon dioxide (CO₂), methane (CH₄) and nitrous oxide (N₂O).  Of these activities, land use change, which largely transforms natural habitat into agricultural land, is of growing concern due to burgeoning global populations and ecological disruptions caused by common agricultural practices like irrigation and fertilization.  Disruptions of this nature presumably affect the mechanisms behind GHG emission and sequestration and as such this project investigates the effect of three irrigation rates (100% evapotranspiration (ET), 80% ET and 60% ET) and three fertilization rates (100 lbs N acre^-, 150 lbs N acre^- and 200 lbs N acre^-) on N₂O daily soil fluxes in a fresh market tomato crop grown on a sandy loam soil.  The study collected 270 daily N₂O flux measurements which were sampled one day prior, the same day and one day post fertilizer application with a mean daily flux equal to 458.23 μg N m^-2 d^-.  Irrigation and fertilization rate each showed a significant effect (p=0.05) on N₂O emissions in one of ten sampling events with the 100% ET irrigation rate treatment and the 200 lbs N acre^- fertilizer rate treatment showing increased N₂O emission rates.  Additionally, correlations between N₂O emissions and site-specific characteristics like, soil C:N, leaf area index, pH and EC, were investigated but no significant correlation could be established from this study.  Interpretation of these results could lead to the postulation that through incremental additions of fertilizer and irrigation the effect of high rates can be mitigated with respect to N₂O emissions.