Modeling the biogeochemical process of the phosphorus cycle and assessing the phosphorus fertilization in China

Jie Zhang, of Tsinghua University, China, investigated ways of improving agricultural management to maintain crop yields while reducing phosphorus pollution.

Jie Zhang

Jie Zhang

Introduction

Phosphorus is a major limiting nutrient for plant growth. Modern agriculture relies heavily on phosphorus fertilizer, which is mainly derived from phosphate rock. It is a nonrenewable resource and current global reserves may be depleted in 50-100 years. The locations of phosphate reserves concentrate in few countries. The locations are highly sensitive and the price changes according to the political and corporate agenda, which may lead to social unrest and political conflicts. Aquatic eutrophication, caused by emissions of nitrogen and phosphorus from farmland, is a common and serious problem. It is essential to find a more integrated and effective approach to reducing phosphorus in the argo-ecosystem while maintaining crop yield and minimizing environmental risk.

Methods

Firstly, we modeled the phosphorus cycle in the soil-plant system based on the long-term field experiments of China. We conducted a sensitivity analysis to identify the suitable model parameters for which calibration was needed. The sites-based work supplied information for Chinese simulation. Secondly, we built the gridded China Environmental Policy Integrated (EPIC) model based on the IIASA global EPIC model, with updated Chinese local data. Then, running the model for 31 years to simulate the rain-fed and irrigated maize yields, nitrogen stress, phosphorus stress, temperature stress, and water stress. Finally, based on the gridded China EPIC model, we run the model from 1918 to 2010 to get the soil available phosphorus in Chinese top soil and analyze the soil phosphorus dynamics in China.

Results and Conclusion

We first used long-term monitoring data to do sensitivity analysis, calibrate and validate the mechanistic model EPIC. The sensitivity analysis results indicate that EPIC model is able to simulate long-term crop production, soil organic carbon changes and soil P dynamics in China. PSP, PARM(20), and PARM(77) are among the most important parameters and the suitable numbers are 0.1-0.5,0.1-0.8, and 0.6, respectively. Second, we built the gridded China EPIC model to simulate the long-term maize yields, soil available phosphorus, nitrogen stress, phosphorus stress, water stress, and temperature stress. The results show that EPIC with detailed information is robust for long-term production and P simulation and can be used for further analysis and predictions.

Reference

[1] Cordell D, Drangert J O, White S (2009) The story of phosphorus: global food security and food for thought. Global environmental change 19(2): 292-305.

Supervisors

Juraj Balkovic and Ligia Azevedo, Ecosystem Services and Management Program, IIASA

Note

Jie Zhang, of Tsinghua University, China, is a citizen of China. She was funded by the IIASA Chinese National Member Organization 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.


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Last edited: 02 February 2016

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