Nitrous oxide emissions from turfgrass lawns as a result of fertilizer application: a meta-analysis of available literature

Urban turfgrass lawns are known to contribute towards global anthropogenic nitrous oxide emissions. However, available literature on lawn N2O emissions is varied and inconclusive. To our knowledge, an effort to compile and understand urban lawn N2O emissions is, as yet, lacking. In the present article, a metaanalysis was conducted to evaluate the effect of lawn fertilizer application on N2O emissions relative to nofertilizer application, along with an examination of the variation of this effect with respect to the type and amount of fertilizer. The results show that lawn N2O emissions from fertilized plots are significant and are 41% (0.29 g N2O-N/m(2)/year) higher than that of control plots. However, studies with low N-input (<150 kg/ha) show higher percentage (40) of N2O emission than those with high N-input (22). Further, N2O emissions are higher for urea application plots (37%) compared to other-than-urea plots (30%), which consisted mostly of enhanced efficiency fertilizer plots. Overall, the results of this meta-analysis underscore current understandings of the effect of fertilizer on soil N2O emissions, although it indicates that fertilizer amount is not the only driver of lawn N2O emissions. Also, the sub-group analysis of fertilizer type reinforces the importance of enhanced efficiency fertilizers in reducing emissions which has clear policy implications. To improve our understanding of lawn N2O emissions, more long-term studies that are well-documented, and geographically widespread, are recommended to build a database that can reduce uncertainties and facilitate long-term evaluations.