Global Meta-Analysis of Nitrate Leaching Vulnerability in Synthetic and Organic Fertilizers over the Past Four Decades

The significance of nitrogen in agricultural ecosystems cannot be overstated; however, it can pose a threat to the environment when it leaches into groundwater. This comprehensive meta-analysis sheds light on the complex relationship between organic and inorganic fertilizers and nitrogen leaching, encompassing 39 years of data. The results indicate that the impact of fertilizers is dependent on crop type, soil properties, and fertilization practices. Vegetables treated with synthetic fertilizers were found to have the highest levels of nitrogen leaching, while grasses exhibited the lowest. Soil texture was also determined to be a significant factor, with coarser soils leading to higher levels of leaching than medium or fine soils. The meta-analysis showed that organic sources resulted in an average of 16% higher losses of nitrate-N, but there was no significant difference between organic and synthetic N fertilizers in terms of leaching overall. These findings provide valuable insights for the responsible management of nitrogen and to further our understanding of the impact of fertilizers on nitrate pollution.