Research Projects

Sustainable Nitrogen Management Across Spatial and System Scales

Managing Nitrogen (N) is often considered as farmers’ responsibility; however, what is produced in farm and how N fertilizer is managed are also affected by stakeholders beyond farm. Funded by National Science Foundation, this project aims to improve N management in the Chesapeake Bay watershed and throughout the country by developing a N management framework that encompasses the complex N dynamics across systems and spatial scales, yet simple enough to guide policies and actions of various stakeholders. This project includes four major deliverables: 1) a hierarchical framework across systems including Cropping system nested within Animal-crop system, which is nested within the Food system, and finally nested within Ecosystem (the CAFE framework); 2) an N budget database according to the CAFE system framework on various spatial scales; 3) a case study for the Chesapeake Bay watershed to implement the CAFE system framework; 4) education and stakeholder engagement programs integrated with the research to improve the project and broaden its impacts.

Sustainable Agriculture in the nexus of food, energy, water, and nutrient on national and global scales

Funded by National Science Foundation, this project will assist decision making on a national scale and to visualize the global implications of agricultural intensification strategies, by synthesizing data from multiple disciplines across different spatial and temporal scales, and developing statistical methods and process-based models to analyze and simulate the integrated cyber-human-physical system of agricultural production. Since the beginning of the project, we have been rigorously testing the impact of trade on agriculture sustainability in China and U.S., and improving the representation of crop management in the Global Change Assessment Model to project the impacts of agricultural intensification. We are also collaborating with high schools in China and U.S. to develop course materials for sustainable agriculture.


Sustainable Agriculture Matrix (SAM)

The ratification of Sustainable Development Goals demonstrates the determination of the international communities in moving towards a sustainable future. To make the commitment accountable, an independent and transparent measurement of countries’ sustainability is essential. Among all sectors, agriculture is the one fundamental to all three pillars of sustainability, namely environment, society, and economy. However, the definition of a sustainable agriculture and the feasibility of measuring it remain elusive, in part because it encompasses both biophysical and socio-economic components that are still poorly integrated. Therefore, with supports from National Science Foundation and National Socio-Environmental Synthesis Center (SESYNC), Xin has been coordinating a highly interdisciplinary team of experts to develop a Sustainable Agriculture Matrix, a collection of indicators measuring sustainable agriculture from environmental, social, and economic dimensions, on a national scale (Zhang et al., 2017;


Sustainable Nitrogen and Phosphorus management in crop production

Following Xin’s research on sustainable nitrogen management, she has been leading a research project to investigate the historical trends of national Phosphorus (P) budgets (including input and output) in crop production around the world. With the founding support by OCP Research, LLC, the team developed a database of P budget and PUE by region and crop type, identified and tested a group of socioeconomic and ecological drivers critical for PUE improvement, projected P fertilizer consumption up to 2050 under various policy and technology scenarios, and identified policy and technology implications for addressing the triple challenges of food security, P supply, and the environment. The project findings are under review.


Tracking fast-evolving National Nitrogen budgets in crop production

To understand how well we have been able to quantify Nitrogen inputs and emissions in crop production so far, Xin has been leading a voluntary effort by about ten major research groups on nitrogen cycles to compare the existing N budget estimates from various approaches and spatial scales and assessed their uncertainties in a systematic manner. This first-of-its-kind comparison on crop N budgets has revealed major gaps in our understanding of N budgets, including the lack of high quality data in crop N contents and detailed location- and crop-specific fertilization data.

Recognizing the existing challenges and urgent demands in quantifying nutrient budgets, Xin have been working with several colleagues on organizing a special issue on “Quantifying Nutrient Budgets for sustainable nutrient management” (