Recently, Professor Zhang Jia'en's team from the College of Resources and Environment at South China Agricultural University and the Guangdong Provincial Laboratory of Lingnan Modern Agricultural Science and Technology, in collaboration with partners, conducted a comprehensive global-scale data integration analysis for the first time. They carried out a full life cycle assessment of nitrogen fertilizer input in the production processes of wheat, corn, and rice, quantitatively analyzing the carbon footprint of nitrogen fertilizer input in crop production. The related findings were published in "Global Change Biology."
With the continuous increase in global population and food demand, the use of fertilizers has become an important means to ensure crop yields and global food security. Wheat, corn, and rice cover 47% of the global agricultural land area, with nitrogen fertilizer usage reaching 52.5TgN, accounting for over half of the global agricultural nitrogen fertilizer consumption. However, there is still a lack of quantitative analysis on the carbon footprint of nitrogen fertilizer input in farmland at a global scale, leading to an unclear understanding of the greenhouse effect caused by agricultural nitrogen fertilizer input.
To address this, Professor Zhang Jia'en's team conducted a full life cycle assessment of nitrogen fertilizer input in the production processes of the three major crops mentioned above through global data integration. They quantified the carbon fixation and emissions directly and indirectly generated after nitrogen fertilizer input, quantitatively analyzed the carbon footprint of nitrogen fertilizer input in crop production, and predicted its changing trends under different future scenarios.
The research results indicate that the net carbon emissions from nitrogen fertilizer application in grain production processes in 2019 amounted to 7.4GtCO2 equivalent. The contributions of the initial stage of fertilizer production (production and transportation), agricultural production stage (agricultural application and plant-soil system absorption), and post-harvest stage of agricultural products (food, feed, biofuels, and losses) were 2%, 11%, and 87%, respectively. Global intercontinental analysis shows that although Asia is the largest grain production region, North America has the highest carbon footprint after agricultural product harvest (2.5GtCO2 equivalent), accounting for 38% of the total carbon footprint contribution. Predictions of the carbon footprint of agricultural production under different scenarios revealed that without improving nitrogen fertilizer use efficiency, agricultural nitrogen fertilizer input to meet global food demand by 2100 will result in 21.2GtCO2 equivalent of carbon emissions.
In order to meet the goals of mitigating global climate change, the study suggests that by considering measures such as improving nitrogen fertilizer use efficiency (an average increase of 6% for the three major crops), enhancing production techniques, reducing food losses, and improving global dietary habits, the carbon footprint of global grain crop nitrogen fertilizer input by 2100 could be reduced to 5.6GtCO2 equivalent. These research findings provide a basis for guiding how agricultural production and consumption practices can contribute to the "dual carbon" goals.
Related Paper Information: https://doi.org/10.1111/gcb.17277
