Through her innovative investigations of environmental, economic, and social drivers of sustainable agriculture, metrics that quantify sustainability, and in-depth nutrient budget analyses, Xin Zhang has moved the discussion on sustainable agriculture. Her seminal 2015 paper in Nature, cited nearly a thousand times, is the most comprehensive and insightful analysis of national and global trends in agricultural nitrogen use efficiency (NUE). It demonstrates how variation of per capita gross domestic product, fertilizer-crop price ratios, and national crop mixes affect NUE among countries and over time and how these trends affect associated N surpluses that lead to air and water pollution. Her students’ analysis of phosphorus use efficiency is in press. Xin also led an in-depth analysis of global N budgets, skillfully coordinating cooperation of 10 prominent international research groups to explore the causes of discrepancies among their N budget data. A resulting benchmark data set will serve future model intercomparisons so that differences due to model structure can be distinguished from differences in their input data. Xin led an overview of the state of N budget science commissioned for an AGU Centennial review in Global Biogeochemical Cycles. Xin’s most challenging and innovative work yet is her Sustainable Agriculture Matrix (SAM). Sustainability has been difficult to define and quantify, especially in agriculture, and yet it is crucial for food security, economic prosperity, and environmental quality. Xin made into a reality the conceptual idea of renowned agronomist M. S. Swaminanthan for a matrix of quantitative indicators of agricultural sustainability. Leading a team of international experts from agronomy, ecology, economics, and social science and from academia, government, nongovernmental organizations, and the private sector, she published SAM 1.0 as a policy-relevant tool of quantitative indicators (SAM 2.0 is in the works), which moves the discussion from a one-dimensional focus on increasing yields toward coordinated thinking and actions among social, economic, and environmental dimensions of agriculture. It enables policymakers to visualize their countries’ historical trajectories of progress toward sustainability goals and to examine trade-offs and synergies among environmental and socioeconomic consequences. Recognizing her impact on the field, Xin serves on several international advisory panels and is a frequent keynote speaker. Xin’s research addresses a crucial global issue facing the world today, namely, how to make agriculture sustainable as global population grows, while maximizing yields on limited land and minimizing associated environmental impacts. These crucial contemporary issues will only grow in importance, and Xin Zhang is helping illuminate a pathway to sustainable solutions. —Eric A. Davidson, Appalachian Laboratory, University of Maryland Center for Environmental Science, Frostburg

Thank you, Eric and colleagues, for the nomination and for your kind words in the citation. I am truly honored and humbled to receive the AGU Global Environmental Change Early Career Award. I would like to take this opportunity to share the honor and joy with all my mentors, colleagues, and students. I am truly proud of what we have achieved together, and I am looking forward to continuing our team efforts in the years to come. I am particularly thankful to have great mentors guiding and supporting me as I am finding my path to fulfill a passion for environmental conservation and sustainable development. I am especially grateful to Prof. C. S. Kiang, who has had a profound influence on me with his global vision and incessant passion for positive solutions. I greatly appreciate my Ph.D. adviser, Prof. Xuhui Lee, who sharpened my skills in critical thinking and data analysis while allowing me to venture out and experience different roles in organizations such as the United Nations. My postdoc adviser, Prof. Denise Mauzerell, really enabled me to become more confident and comfortable as a female scientist working in interdisciplinary settings. I am also very fortunate to work with Prof. Eric Davidson, who, with his day-to-day practice, demonstrates how to be an inspiring mentor, visionary leader, effective collaborator, and thoughtful friend. I would like to thank the students and postdocs in my lab, especially Tan Zou, Srishti Vishwakarma, Guolin Yao, and Jing Zhao. Thank you for putting your trust in me as your adviser and working with me tirelessly over the past years. My growth as an independent researcher has also greatly benefited from the collaborative environment and great colleagues at the University of Maryland Center for Environmental Science. Finally, I am beyond grateful to my husband and parents for their unconditional love and support. The world is facing unprecedented environmental and societal challenges, and much hope has been placed on the agricultural sector to sustain the food supply and offer climate solutions (e.g., biofuel and soil carbon sequestration). However, the immense expectation for agriculture has not been matched with the necessary level of support in terms of talent and resources. Meeting this expectation has been further challenged by more frequent extreme weather events, political instability, high input prices, an aging agricultural community, and more. I sincerely hope that we can continue to work across the boundaries of disciplines, sectors, and nations; raise the awareness of agricultural sustainability challenges; and attract more young and creative minds to reshape the agriculture-food system in a more sustainable manner. —Xin Zhang, University of Maryland Center for Environmental Science, Frostburg