Abstract
Improvements in nitrogen use efficiency in crop production are critical for addressing the triple challenges of food security, environmental degradation and climate change. Such improvements are conditional not only on technological innovation, but also on socio-economic factors that are at present poorly understood. Here we examine historical patterns of agricultural nitrogen-use efficiency and find a broad range of national approaches to agricultural development and related pollution. We analyse examples of nitrogen use and propose targets, by geographic region and crop type, to meet the 2050 global food demand projected by the Food and Agriculture Organization while also meeting the Sustainable Development Goals pertaining to agriculture recently adopted by the United Nations General Assembly. Furthermore, we discuss socio-economic policies and technological innovations that may help achieve them.
Generated Summary
This research examines historical patterns of agricultural nitrogen-use efficiency (NUE) across 113 countries from 1961 to 2011 to address the triple challenges of food security, environmental degradation, and climate change. The study analyzes the relationship between economic development and agricultural N pollution, particularly focusing on the Environmental Kuznets Curve (EKC) to understand how N pollution changes with income growth. The methodology involves analyzing historical data on agricultural N use, crop yields, and economic indicators such as GDP per capita. The research also investigates the impact of various factors, including crop mixes and fertilizer-to-crop price ratios, on NUE and N surplus (Nsur). The goal is to identify effective strategies, policies, and technological innovations to improve NUE and promote sustainable agricultural development, meeting both food security needs and environmental goals. The study acknowledges that improving NUE requires more than technical knowledge; it also requires understanding the cultural, social, and economic factors that influence the adoption of NUE technologies and management practices.
Key Findings & Statistics
- More than half the world’s population is nourished by crops grown with synthetic nitrogen (N) fertilizers.
- The global population is projected to increase by 2-3 billion by 2050.
- The study analyzed historical patterns of agricultural N use in 113 countries from 1961–2011.
- Average global NUE in crop production needs to improve from ~0.4 to ~0.7 to meet the dual goals of food security and environmental stewardship in 2050.
- N surplus (Nsur) is defined as the sum of N inputs (fertilizer, manure, biologically fixed N, and N deposition) minus N outputs.
- The study found that 56 countries show bell-shaped relationships between Nsur and GDP per capita, accounting for about 87% of N fertilizer consumption and about 70% of harvested area of all 113 countries.
- By 2011, the rate of increase in Nsur had only slowed or leveled off and had not yet actually decreased in 28 of the 56 countries.
- The study used a fixed effects model across 113 countries to test the existence of a sustainable intensification phase, using a five-decade record (1961–2011) of Nsur and GDP per capita.
- The projected 2050 global food demand of 107 Tg N yr-1.
- Globally, NUE would increase from ~0.4 to ~0.7, while the crop yield would increase from 74 Tg N yr-1 to 107 Tg N yr-1.
- The global average Nsur target would need to be 39-78 kg N ha-1 yr-1 across the 2010 harvested area of 1.3 billion hectares.
- Over 60% of N pollution is estimated to originate from crop production.
- The study analyzed China and USA, with the USA’s NUE at approximately 0.5 while China has a lower NUE, influenced by crop mixes and fertilizer practices.
- In China, the fertilizer to maize price ratio is positively correlated with NUE.
- The fraction of harvested area for fruit and vegetable production negatively correlates with NUE.
Other Important Findings
- The study suggests that many countries show a pattern similar to an environmental Kuznets curve (EKC), where N pollution first increases and then decreases with economic growth.
- The study highlights the importance of socio-economic circumstances and policies in influencing the turning points of the EKC.
- The research indicates that average global NUE in crop production needs to improve from approximately 0.4 to 0.7 by 2050 to meet food security and environmental stewardship goals.
- The study emphasizes the role of sustainable intensification of agriculture in achieving the second phase of the EKC, including the use of cultivars best adapted to local conditions, improved water management, and precision fertilizer application.
- The research notes that the relationship between Nsur and NUE results in nearly mirror images.
- The study emphasizes the need for tailored regulations, incentives, and outreach to local conditions to improve NUE.
- The study found that fertilizer to crop price ratios (Rfc) affect farmer decisions regarding their choice of technologies and practices for nutrient management.
- The results indicate that maize prices are linearly correlated with most major crops.
- The study suggests that government subsidies have an effect on fertilizer prices and NUE.
- The research highlights that improving NUE needs more than technical knowledge; it requires an understanding of the cultural, social, and economic factors.
- The study emphasizes that to reach ambitious NUE goals, implementation of technologies and management practices is required at the farm scale.
Limitations Noted in the Document
- The EKC concept has been criticized for concerns regarding statistical analyses of time series data that may be non-stationary.
- Classic empirical studies on EKC have been criticized because of concerns regarding statistical analyses of time series data that may be non-stationary.
- The turning point for transitioning to declining environmental degradation is highly variable among pollutants and among countries.
- The data used to construct the models have limitations due to the need for improved data quality and international harmonization of data standards.
- The study notes that the crop production scenario used for 2050 makes assumptions about future dietary choices, which are beyond the scope of the study.
- The study primarily focuses on crop production due to data availability and does not fully address nutrient management in livestock operations, which is recognized as an area needing more attention.
- The research acknowledges that not all fertilizer subsidies are inappropriate, particularly in areas with poor infrastructure.
Conclusion
The study underscores the critical need for improving nitrogen use efficiency in crop production to address the intertwined challenges of food security, environmental degradation, and climate change. The analysis reveals that while many countries exhibit an Environmental Kuznets Curve (EKC) pattern, where N pollution initially increases and then decreases with economic growth, the trajectory is neither automatic nor inevitable. Socio-economic factors, policy choices, and technological adoption significantly influence the turning points of the EKC, highlighting the importance of tailored strategies. The ambitious goals for NUE improvement, coupled with yield increases, require a multifaceted approach. This includes the adoption of sustainable intensification practices, effective policy interventions, and the promotion of technological innovations. The research emphasizes that the path toward achieving these goals is not uniform; countries will need to adapt their strategies based on their unique contexts. Furthermore, the study highlights the need for ongoing data collection, international collaboration, and a focus on the broader food system, including livestock management and dietary choices. As stated in the study, “The turning point in European Union (EU) countries appears to have been reached at least in part owing to policies.” Thus, policies and practices need to be geared toward better NUE for the future. In conclusion, the research advocates for a holistic approach that integrates scientific advancements, socio-economic considerations, and effective policy implementation to ensure that agriculture can sustainably meet global food demand while minimizing environmental impacts. The study further argues that, “Achieving ambitious NUE targets while also increasing yields to meet future food demands requires implementation of technologies and management practices at the farm scale.” Therefore, a concerted effort is necessary to advance agricultural practices that promote high NUE and protect the environment.