Assessing cover crop impacts on agroecosystem productivity and sustainability in the U.S. Midwest

This dissertation examines the impacts of cover crops on agroecosystem productivity and sustainability in the U.S. Midwest. Cover crops grow during the normal fallow period between main crop growing cycles to protect and enhance soil health. The U.S. Midwest agroecosystem is a dominant agricultural zone characterized by its extensive cultivation of corn and soybeans. The region faces significant environmental challenges exacerbated by climate change, including increased temperature and precipitation variability, which affect agricultural sustainability and productivity. The primary focus of this research is to address two key science questions related to cover crops: What are the impacts of cover crops on agroecosystem productivity and sustainability in the U.S. Midwest? How can we manage cover crops in the U.S. Midwest to balance agroecosystem productivity and sustainability? Chapters 2 and 3 of this dissertation investigate the impacts of cover crops on cash crop yield and soil organic carbon (SOC). These two chapters unravel the controlling factors of the cover crop impacts, including management practices and environmental conditions, and synthesize the mechanisms through which cover crops interact with agroecosystem carbon cycles. Chapter 4 introduces an innovative approach to quantify the temporary carbon benefits from nature-based climate solutions (NbCS) with a combination of the process-based model and the tonne-year accounting method, using cover crops as an example, which challenges traditional views on the necessity of long-term commitments in NbCS by demonstrating that shorter-term implementations can still achieve significant climate change mitigation benefits. In Chapter 5, the dissertation expands the scope to regional-scale impacts by applying the Model-Data Fusion (MDF) approach, which integrates remote sensing data and in-situ measurements to calibrate and validate the ecosys model, enhancing the model accuracy in predicting the environmental and agronomic impacts of cover crops across the U.S. Midwest. The findings underscore the potential increases in SOC benefits with greater governmental support and funding, such as through the Environmental Quality Incentives Program (EQIP) program. Chapter 6 addresses the quantification of cradle-to-farmgate Carbon Intensity (CI) using a combination of the ecosys model, Life-Cycle-Analysis (LCA), and the MDF approach. This comprehensive framework significantly reduces uncertainty in CI quantification at the field level and can be scaled to regional-level assessment, providing insights for policymakers and farmers about sustainable agricultural practices. Overall, this dissertation enhances scientific understanding and provides robust evidence supporting the strategic use of cover crops in mitigating climate change and enhancing soil health. It offers practical insights and guidelines to help farmers, policymakers, and the agri-food industry make informed decisions that contribute to sustainable agriculture in the face of climate change.

Name thesis:degree_name

Ph.D.

Level thesis:degree_level

Dissertation

Discipline thesis:degree_discipline

Natural Res & Env Sciences

Grantor

University of Illinois at Urbana-Champaign

Year dc:date

2024

Author dc:creator

• Qin, Ziqi

Contributors dc:contributor

• Guan, Kaiyu
• Lee, Dokyoung
• Ainsworth, Elizabeth
• Margenot, Andrew
• Tang, Jinyun

• Cover Crops
• Ecosystem
• Process-based Modeling
• Climate Change
• Soil Organic Carbon

Statement dc:rights

• Copyright 2024 Ziqi Qin

Language dc:language

en, eng

Handle dc:identifier

https://hdl.handle.net/2142/127435

OAI record oai:identifier

https://www.ideals.illinois.edu/oai-pmh?verb=GetRecord&metadataPrefix=etdms&identifier=oai%3Awww.ideals.illinois.edu%3A2142%2F127435