Riparian forests haven been proven to possess higher potential to remove nitrate from agricultural run-off through denitrification. However, it is not clear whether prolonged exposure of riparian soils to surface nitrogen (N) loading will affect denitrification rates and its end products. This research compares denitrification and N₂O emission rates from riparian forests exposed to plant nurseries nutrient run-off to those from similar forests not exposed to chronic nursery nutrient loading. Nurseries run-off also contain high levels of phosphates and there are conflicting reports on the effect of phosphate on denitrification, hence the impact of phosphate on denitrifier activity was also investigated. Bulk and intact soil cores were collected from N exposed and non-exposed forest sites for the determination of denitrification and N₂O emission rates, whereas denitrification potential was determined using soil slurries. Denitrification rates increased 2.7-fold when amended with 30 μg NO₃-N g^-1 soil in both the N-exposed and non-exposed forest soils. However, addition of 60 μg NO₃-N g^-1 soil led to a significant 4-fold increase in denitrification rates in the non-exposed soils compared to a 2.9-fold increase in the N-exposed soils. Net N₂O emissions were 1.4 and 1.7 times lower from the non-exposed soils compared to the N exposed soils at 30 and 60 μg NO₃-N g^-1 soil amendment rates, respectively. Similarly, denitrification potential increased 18 times on average in response to addition of 15 μg NO₃-N g^-1 soil in the N exposed and non-exposed soil slurries compared to the unamended soils. Phosphate addition (5 μg PO₄–P g^-1 soils) to soil slurries and intact cores did not affect denitrification rates in all the sites. These observations suggest that chronic nitrogen loading did not affect denitrification potential of the riparian forests; however, it resulted in relatively higher N₂O emissions during denitrification compared to emission rates from non-exposed forests.