In the last several decades, global food production growth has been triggered by a large increase in the amount of fertilizer application; for example, global N fertilizer application increased nine-fold and global P fertilizer tripled from 1960 to 2010 . Consequently, significant environmental issues have been caused at different scales (e.g., air and groundwater pollution, eutrophication, soil degradation, ecosystems diversity reduction, and coastal water pollution) . It is important to identify the hotspots of crop-specific nitrogen and phosphorus pollution on a global scale.
PEPIC, a grid-based Environmental Policy Integrated (EPIC) model under the Python environment, was used to investigate the nitrogen and phosphorus pollution for four major crops: maize, rice, soybean, and, wheat. Here, total annual losses of N (including the annual losses of N to air and water) and P (the annual losses P to water) to environment were considered as the N and P pollution. To identify the hotspots of N and P pollution, a global food production unit map obtained from  was used to aggregate the grid-based outputs.
Total annual losses of N to environment (aggregated from four crops based on crop harvested areas) ranged mainly between 15 and 90 kg N ha-1 (Figure 1a). However, southeastern parts of China, Republic of Korea, and Chile presented the higher amount (larger than 150 kg N ha-1). Generally, total annual losses of P to the environment (also aggregated from four crops based on crop harvested areas) were less than 10 Kg P ha-1 in most of the world, especially in Africa, west parts of Asia, and western parts of USA (Figure 1b). On the other hand, hotspots were located in southeastern parts of China, Republic of Korea, Japan, Chile, and New Zealand, where total losses of P were larger than 30 kg P ha-1.
Using this biophysical crop model, it is possible to spatially explicitly simulate the crop-specific N and P pollution. In this study, the hotspots of global N and P pollution at the level of food production unit were identified. To reduce the N and P pollution in these high pollution areas, smart agriculture management practices should be introduced.
 Klimont Z (2013). Our Nutrient World: the challenge to produce more food and energy with less pollution. Centre for Ecology and Hydrology (CEH).
 Elliott J, Deryng D, Müller C et al. (2014). Constraints and potentials of future irrigation water availability on agricultural production under climate change. P Natl Acad Sci USA, 111(9): 3239-3244.
Rastislav Skalsky and Juraj Balkovic, Ecosystem Services and Management Program, IIASA
Wenfeng Liu, of the Swiss Federal Institute of Technology Zurich and the Swiss Federal Institute of Aquatic Science and Technology, is a citizen of China. He was self-funded and worked in the Ecosystem Services and Management Program during the YSSP.
Please note these Proceedings have received limited or no review from supervisors and IIASA program directors, and the views and results expressed therein do not necessarily represent IIASA, its National Member Organizations, or other organizations supporting the work.
Last edited: 09 February 2016
YSSP Coordinator and Team Leader Young Scientists Summer Program - Capacity Development and Academic Training Unit
International Institute for Applied Systems Analysis (IIASA)
Schlossplatz 1, A-2361 Laxenburg, Austria
Phone: (+43 2236) 807 0 Fax:(+43 2236) 71 313