A comprehensive meta-analysis of nitrate leaching from wheat, rice, and maize cultivation on a global scale

Cereal crops are a vital source of food for the global population, but their cultivation can also result in nitrate leaching into the soil and groundwater, posing potential environmental and health risks. This meta-analysis aimed to assess the global extent of nitrate leaching from the cultivation of wheat, rice, and maize, three major cereal crops grown worldwide. A comprehensive literature search was conducted to identify relevant studies that reported nitrate leaching. The findings indicate that overall nitrate leaching from cereal crops varies greatly but is significantly (p < 0.0001) higher for wheat-maize rotation compared to wheat and rice. Additionally, nitrate leaching losses were influenced by factors such as the rate, timing, and method of nitrogen fertilizer application, with higher mean leaching observed in wheat-maize rotations with organic fertilizer application (93.6 kg N ha−1) and from wheat when fertilizers were applied in a full dose (84.8 kg N ha−1). This meta-analysis highlights the importance of sustainable agriculture practices as optimum use of nitrogen fertilizers to reduce nitrate leaching and mitigate its potential environmental and health impacts. The results of this study can be used by policy makers and agriculture practitioners to inform decision-making and promote sustainable agriculture practices.