Characterizing nutrient budgets on and beyond farms for sustainable nutrient management

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dc.contributor.advisorZhang, Xinen_US
dc.contributor.authorZou, Tanen_US
dc.contributor.departmentMarine-Estuarine-Environmental Sciencesen_US
dc.contributor.publisherDigital Repository at the University of Marylanden_US
dc.contributor.publisherUniversity of Maryland (College Park, Md.)en_US
dc.date.accessioned2023-06-23T06:10:19Z
dc.date.available2023-06-23T06:10:19Z
dc.date.issued2023en_US
dc.description.abstractThe production and security of food are heavily reliant on adequate nitrogen (N) and phosphorus (P) inputs in agriculture. However, ineffective management of N and P from the farm to the table can result in nutrient pollution, triggering both environmental and social issues. Moreover, another important challenge for P management is limited and unevenly distributed P resources, leading to P scarcity in many parts of the world. Inefficient use of nutrients in agriculture-food systems is the root cause of both nutrient pollution and scarcity. To improve nutrient use efficiency and reduce nutrient loss, it is crucial to address key knowledge gaps in nutrient management research, which include inadequate quantification of nutrient budgets, as well as identifying and addressing nutrient management challenges across various systems and spatial scales. This dissertation tackles the knowledge gaps in two studies, including a global-scale study and a case study of the Chesapeake Bay watershed. In the global-scale study, I establish and utilize a unique P budget database to assess historical P budget and usage patterns at the national and crop type level from 1961 to 2019. This analysis reveals the impacts of various agricultural and socioeconomic drivers on cropland P use efficiency (PUE), including N use efficiency (NUE), fertilizer-to-crop-price ratio, farm size, crop mix, and agricultural machinery. The findings indicate that P management challenges vary by country and spatial scale, necessitating tailored country-level strategies. The regional-scale study applies a framework adapted from N studies to the Chesapeake Bay watershed, analyzing nutrient (N and P) management across systems and spatial scales. This approach uncovers that nutrient loss potential beyond crop farms is larger than that at crop farms. This highlights the need to enhance nutrient management and curb nutrient loss in animal production, food processing and retail, and human consumption. This study also identifies a large potential for meeting cropland nutrient demand by increasing the recycling of nutrients in manure, food waste, and human waste. To tackle the challenges surrounding nutrient management in the watershed, it is imperative to target factors significantly related to nutrient management, such as agricultural practices, soil properties, climate change, and socioeconomic conditions. This dissertation contributes to a deeper understanding of N and P management challenges, gaps, priorities, hidden drivers, and potential solutions at various scales, from regional to national and global levels. The analytical procedures and statistical tools developed in this dissertation are generalizable, allowing for their adaptation to similar nutrient management studies in different regions and for diverse research purposes.en_US
dc.identifierhttps://doi.org/10.13016/dspace/jlse-gcdj
dc.identifier.urihttp://hdl.handle.net/1903/30029
dc.language.isoenen_US
dc.subject.pqcontrolledEnvironmental scienceen_US
dc.subject.pqcontrolledEnvironmental studiesen_US
dc.subject.pqcontrolledEnvironmental managementen_US
dc.subject.pquncontrolledagricultureen_US
dc.subject.pquncontrollednitrogenen_US
dc.subject.pquncontrollednutrient budgetsen_US
dc.subject.pquncontrollednutrient managementen_US
dc.subject.pquncontrollednutrientsen_US
dc.subject.pquncontrolledphosphorusen_US
dc.titleCharacterizing nutrient budgets on and beyond farms for sustainable nutrient managementen_US
dc.typeDissertationen_US

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