Factors Influencing N2O Emissions from Vegetable Crops and Comparison with Other Food Crops: A Meta-Analysis

Abstract

The use of nitrogen fertilisers to increase crop productivity increases global nitrous oxide (n₂o) emissions. This study used a meta-analysis technique to evaluate the influence of nitrogen fertilisers (rates and types) and other factors (soil organic carbon, soil nitrogen and ph) on n₂o emissions from vegetable crops, which were then compared to emissions from three other food crops. A total of 176 field measurements on n₂o emissions for vegetable crops were collected from 33 peer-reviewed papers and 168 measurements for potato, corn and wheat crops were collected from 38 peer-reviewed papers. Vegetable crops produced higher n₂o emissions than wheat and potato crops. The average amount of nitrogen fertiliser application for vegetable crops was 287 kg n ha^-1, resulting in average cumulative n₂o emissions of 4.52 kg n₂o-n ha^-1. Nitrogen rates of over 200 kg ha^-1 applied for vegetable crops were strongly, positively associated with n₂o emissions. The impact of inorganic nitrogen fertilisers on n₂o emissions was significantly higher than organic nitrogen fertilisers. Further studies should include more factors driving n₂o emissions such as soil moisture, soil tillage, soil temperature and soil types to assess their overall impacts on n₂o emissions and help develop mitigation options