Graduate Studies
First Advisor
Bijesh Maharjan
Committee Members
Mitchell Stephenson, Saurav Das
Date of this Version
11-2024
Document Type
Thesis
Citation
A thesis presented to the faculty of the Graduate College at the University of Nebraska-Lincoln in partial fulfillment of requirements for the degree of Master of Science
Major: Agronomy
Under the supervision of Professor Bijesh Maharjan
Lincoln, Nebraska, United States, December 2024
Abstract
Soil health is essential for supporting crop productivity, ecosystem functions, and overall environmental quality. It is influenced by natural factors such as soil type and climate and human-induced agricultural management practices. Understanding and measuring soil health is critical for implementing management practices that support long-term productivity and environmental conservation. Several soil properties and processes may be used as indicators of soil health. Due to the complexity of soil systems and environmental variability, it is crucial to identify soil health indicators that reflect inherent soil and climatic conditions in addition to management effects. Determining indicators sensitive to these natural variations aids in inter-site and broader regional comparisons, helping to prioritize effective, context-specific soil health improvements. This study aimed to identify soil health indicators responsive to soil and climatic variations by analyzing samples from native grasslands in two Major Land Resource Areas (MLRA 106 and 67A) in Nebraska, characterized by distinct soil textures and precipitation regimes. Among over 30 soil properties evaluated, organic matter, pH, phosphorus, and microbial community components (fungal-to-bacterial ratio) were identified as key indicators sensitive to edaphic and climatic factors. These indicators were selected due to their strong responsiveness to the region's natural soil and climate conditions, making them particularly useful for assessing soil health in varied agroecological contexts. Using these identified key soil health indicators, a comparative analysis of soil health was conducted between native grassland sites and croplands within the same agroecological region. The results demonstrate the significant influence of natural soil and climate characteristics on soil health and the differential impact of agricultural management. Our findings underscore the importance of context-specific soil health assessments, offering a robust framework to guide sustainable agricultural practices and improve soil health management across varying environments.
Advisor: Bijesh Maharjan
Comments
Copyright 2024, Lithma Kariyawasam Hetti Gamage. Used by permission