Agronomy and Crop Sciences Commons^™

High Biochar Rate Improves Water Retention In Some Environmentally Sensitive Soils, Samundra Sigdel

Department of Agronomy and Horticulture: Dissertations, Theses, and Student Research

Improving water retention and other hydraulic properties is key to managing soil water and sustaining crop production under fluctuating and extreme weather events. We assessed how wood biochar (836 g C kg^-1) applied at 0, 6.25, 12.5, 25, and 50 Mg ha^-1 affected: i) soil hydraulic properties after 5 years and ii) corn and soybean yield, and biomass production of cereal rye cover crop (CC) and CC mix (cereal rye, radish, and winter pea) in sandy, sloping, and semi-arid soils in the central U.S. Great Plains over 6 years. Biochar affected field saturated hydraulic conductivity (K_{sat …}

Stephen Baenziger, Unl Agronomy & Horticulture, Breeding New Wheat Varieties, Mark Griep, P. Stephen Baenziger

UNL ORCA Interview Series

Stephen Baenziger awarded the ORCA in 2011. He was born in 1951 in Toronto, Canada. When he was an infant, his family immigrated to the U.S., where he grew up in Des Plaines, Illinois. He earned a bachelor's in biological chemistry magna cum laude from Harvard University in Cambridge, Massachusetts. Next, he earned a master's and doctorate in plant breeding and genetics at Purdue University in West Lafayette, Indiana. Over the next decade, he worked for the USDA at Beltsville Agricultural Research Center in Maryland and then at the Monsanto Corporation in St. Louis, Missouri. In 1986, he joined the …

Can Generative Ai Make Farming Decisions? Current Status And Future Pathways: A Case Study In Row Crop Production With Chatgpt, Nipuna Chamara, Yufeng Ge, Joe Luck, Yu Pan, Saleh Taghvaeian, Cory Walters, Christopher Proctor, Daran Rudnick, Daren Redfearn

Department of Agricultural and Biological Systems Engineering: Faculty Publications

The agricultural decision-making process is experience-based, knowledge-dependent, time-sensitive, complex, and driven by historical data. Planting, fertilization, irrigation, and chemigation are key categories in farm decision-making, and currently there is no one-shot decision-support tool that covers all these activities. Generative Artificial Intelligence (AI) models are more advanced than traditional machine learning and deep learning models. These models have been trained on vast amounts of data from the internet, allowing them to accept unstructured data in various forms and generate human-like text, solutions to problems, and scenario predictions. Given this capability, we became interested in exploring the potential of generative AI in …

Evaluating The Impact Of Intercropping Vegetables And Cut Flowers On Yield And Conservation Biological Control, Alliance Igiraneza

Department of Agronomy and Horticulture: Dissertations, Theses, and Student Research

Specialty crops such as vegetables are some of the most susceptible to yield losses and increased management difficulty over time due to pests. One of the potential solutions to this problem, which aims at ensuring the sustainability of the sector, is using conservation biological control practices such as intercropping to increase diversity, while maintaining the economic feasibility and profitability of the system. This study was conducted to evaluate the impact of this management practice using Bell pepper (Capsicum annuum var. King Arthur) as the main crop, intercropped with flowers including zinnia (Zinnia elegans var. Benary’s Giant), sunflower ( …

Cis-Variant Gene-Expression Association Analysis: A Targeted Approach To Identify Functional Cis-Regulatory Variation, Sofiya Arora

Department of Agronomy and Horticulture: Dissertations, Theses, and Student Research

Phenotypic diversity in plants is largely driven by changes in gene function arising from mutations in both the coding and regulatory regions. Regulatory variation is particularly pervasive because it can fine-tune gene expression without disrupting protein function and is therefore less likely to be strongly selected against in natural populations. As a result, it has played a central role in evolution and domestication. In our previous genome-wide eQTL mapping study in maize, nearly two-thirds of the expressed genes were found to harbor detectable cis-expression quantitative trait loci (cis-eQTLs) with strong local effects on gene expression. Though these cis-variants are widespread, …

Quantitative Genetics, Genomics, And Phenomics In Maize And Sorghum, Nikee Shrestha

Complex Biosystems Program: Dissertations and Student Research

Generating the best crop varieties and hybrids requires identifying genes associated with the phenotype of interest and screening thousands of varieties across multiple locations. Quantitative genetics, along with comparative genomics, phenomics, and machine learning approaches, can help us identify target genes associated with the phenotype of interest to develop the right genotypes. Satellite platforms offer logistical and technical advantages in scalability and accessibility and could facilitate plot-level predictions, especially with steadily improving spatial resolution, thereby empowering the large-scale screening of thousands of genotypes across diverse locations. In the first chapter, I evaluated over 20,000 plot-level images of over 80 hybrid …

Assessment Of Super Absorbent Polymer In Soybean Cultivation Under Variable Irrigation Conditions In Nebraska, Ankit Chandra, Abia Katimbo, Ronaldo Marchezan, Martha Nabaggala

Department of Agricultural and Biological Systems Engineering: Presentations and White Papers

Water limitation is a primary constraint to soybean productivity in both irrigated and rainfed systems. Soil-applied superabsorbent polymers (SAPs) have been proposed as a strategy to buffer crops against episodic drought stress; however, their physiological and agronomic performance under varying irrigation regimes remains insufficiently quantified. Here, we evaluate three biodegradable polymer formulations: broader granules (BB), original granules (OG), and powder (PWR) applied at low (17.7 lb/ac) and high (120 lb/ac) rates under full (100% ET), reduced (50% ET), and no irrigation conditions in western Nebraska. Polymer application had negligible effects under full irrigation, with yields comparable to untreated controls. Under …

Effects Of Applying Humic Acid In-Furrow At Potato Planting, Jonathan Tyler Price

Department of Agronomy and Horticulture: Dissertations, Theses, and Student Research

Many products are marketed towards potato farmers that purport to have a positive return on investment for yield and quality. Humic acids, which are comprised of long chained, organic molecules that can be naturally or industrially made, are currently being marketed in this way. The use of these materials is reported to improve nutrient uptake, increase soil health, encourage vigorous growth, and most importantly, increase yields.  From 2023-2025, the in-furrow application of humic acid containing commercial products was evaluated in Pennsylvania on the cultivars ‘Lehigh’ and ‘Waneta’. Black Label Zn, Duo Maxx, Fertiactyl RhiZn, Humi-flex FA, Hydra-Hume, and Monty's Liquid …

Assessment Of Precision Rangeland Management Tools In The Nebraska Sandhills, Hannah K. Allen

Department of Agronomy and Horticulture: Dissertations, Theses, and Student Research

The objective of this thesis is to evaluate tools and management strategies that contribute to rangeland monitoring and livestock distribution in heterogeneous grassland systems of the Nebraska Sandhills. Chapter one reviews relevant literature related to precision livestock management, the Nebraska Sandhills, biomass estimation, and pyric herbivory. The second chapter evaluates the use of fractional green canopy cover (FGCC) derived from the Canopeo mobile application as a rapid method for estimating aboveground biomass in Sandhills rangelands. Biomass samples were collected across topographic positions in both early and late growing season, and relationships between FGCC and clipped biomass were assessed using generalized …

Perceived Barriers To Integrated Crop–Livestock Systems: Evidence From A Nebraska Producer Survey, Omid Tarashtwal

Department of Agricultural Economics: Dissertations, Theses, and Student Research

Integrated crop-livestock systems offer agronomic, economic, and environmental benefits, yet reintegration has been slow across the Northern Great Plains despite sustained interest. Existing research has documented barriers to transition conceptually, but quantitative evidence on which barriers producers perceive as most important and which producer and operation characteristics are associated with stronger barrier perceptions remains limited. This thesis addresses that gap using data from the 2023 Nebraska Agriculture Operator Survey.

The analysis focuses on 241 Nebraska producers, including 179 crop-only and 62 livestock-only operations. Seven models are estimated, combining ordered logit estimation for single-item barriers with linear regression for averaged barrier …

Spatial Variability Of Nitrates And Nitrogen Mineralization Kinetics And Their Effects In Long-Term Tillage Systems, Bibash Rokaya

Department of Agronomy and Horticulture: Dissertations, Theses, and Student Research

Nitrogen (N) and water management are essential for water quality protection and crop production. However, soil N and water are spatiotemporally variable. Soil water spatial dependencies are described in the literature with known associations with preferential flows among other factors. In contrast, a knowledge gap exists on the spatial dependence of soil N mineralization kinetics. We hypothesize that soil N mineralization kinetics and soil water have distinct and cross-correlated spatial characteristics among soil management practices and climatic regions. For the field study, we measured soil-N mineralization kinetics, volumetric water content (VWC), and a suite of soil properties along ~70 m …

Evaluation Of Publicly Available Maize Germplasm Adaptation To Environments In Nebraska, Garrett Snodgrass

Department of Agronomy and Horticulture: Dissertations, Theses, and Student Research

Publicly available maize germplasm represents an important resource for breeding programs seeking to expand genetic diversity and improve hybrid performance. However, effective use requires characterization of per se phenotypic performance of parental lines and evaluation of the parental line’s hybrid progeny adaptation to a given target population of environments. Furthermore, understanding population structure and heterotic grouping is imperative for maximizing efficiency of breeding decisions. The objectives of this study were to (1) evaluate phenotypic performance of parental lines and hybrids across environments in Nebraska, and to (2) refine heterotic group classification of parental lines within the University of Nebraska-Lincoln’s Hybrid …

Hydroponics In The Classroom: Cultivating Plants, Captivating Young People, Stacy A. Adams, Christian Stephenson, Theresa James, Kim Todd

Department of Agronomy and Horticulture: Faculty Publications

Few students take the initiative to pursue coursework beyond that required for progression to graduation. Limited are opportunities that connect educational content to industry application, potentially inspiring young people towards impactful careers. The United States government has emphasized the importance of STEM education to ensure national security and to maintain economic competitiveness globally. STEM education is not a defined discipline but an approach for building knowledge through application and engagement. Developing and managing a hydroponics prototype provides numerous opportunities for embedding STEM content into a fun and interactive project. This poster provides inspiration for constructing a simple deep water culture …

Assessment Of Soybean Response To Irrigation Variability In Eastern Nebraska Using The Aquacrop Model, Anmol Singh, Saleh Taghvaeian, Yufeng Ge, Derek M. Heeren, Frank Bai

Department of Agricultural and Biological Systems Engineering: Faculty Publications

Soybean [Glycine max (L.) Merr.] is a major irrigated crop in eastern Nebraska, where recent expansions in irrigated agriculture and projected trends in irrigation demand necessitate thorough investigations of approaches that can optimize its irrigation management. In this study, the AquaCrop model was calibrated and validated using 19 variable irrigation treatments from a five-year field experiment. The model accurately simulated canopy cover, soil water content, and grain yield, with validation normalized root mean square error (nRMSE) of 12%, 7%, and 7%, respectively. The model was subsequently applied to estimate soybean yield and water requirement during a 15-year period (2010–2024) …

Patch Mow Grazing: Investigating The Effects Of Mowing On Forage Nutritive Value, The Biomass–Nutritive Value Relationship, And Herbivore Selection, Trace R. Stauble

Department of Agronomy and Horticulture: Dissertations, Theses, and Student Research

Herbivore foraging behavior plays a critical role in shaping grassland structural heterogeneity, with selection often driven by forage biomass and nutritive value. Currently, it is thought that herbivores primarily select areas that are greater in nutritive value, and low in biomass. More specifically, disturbances like fire and grazing have been thoroughly studied showing that recently burned and grazed areas are not only higher in nutritive value but disproportionately selected by herbivores in comparison to undisturbed areas. However, most studies address only narrow ranges of defoliation, comparing intensely defoliated sites (< 10 cm) to those that are either not defoliated or have experienced a much longer time since defoliation, thereby decreasing grazing pressure as biomass increases. However, one of the most widely used methods of defoliation in grasslands, mowing, hasn’t been thoroughly studied for its effects on nutritive value, and how it impacts herbivore selection. Our study aimed to (1) evaluate how mowing treatments—i.e., short (5 cm), medium (18 cm), and tall (>30 cm, unmown)—affect nutritive value and herbivore selection, (2) assess …

Cover Crop Influence On Arthropod Biodiversity And Soil–Water Dynamics In A Semi-Arid Maize–Soybean Sequence Of The Nebraska High Plains, Carlos Eduardo De Oliveira Martins

Department of Agronomy and Horticulture: Dissertations, Theses, and Student Research

With the expansion of cover crop (CC) use in semi-arid regions, producers in the Nebraska High Plains are increasingly interested in understanding how CCs influence both beneficial arthropods and soil-water within maize-soybean (Zea mays L., Glycine max [L.] Merr.) rotations. Integrating CCs in these systems can enhance soil water availability and beneficial insect activity, but potential trade-offs include higher early-season water use by CCs and the risk of increasing potential pest populations. This thesis addresses these questions through two complementary studies conducted under field conditions near Brule, Nebraska. The first study evaluated the effects of a multi-species CC mixture …

Evaluating Metamitron Efficacy For Glyphosate-Resistant Palmer Amaranth (Amaranthus Palmeri) Management In Sugarbeet Across The Central High Plains, Abraham Akuoko

Department of Agronomy and Horticulture: Dissertations, Theses, and Student Research

Herbicide-resistant (HR) Palmer amaranth (Amaranthus palmeri S. Watson) is regarded as one of the most prominent weeds within sugarbeet fields across the Central High Plains, with limited chemical control options. Although a few herbicides are available, their use is restrictive due to crop injury concerns and can only be applied at or after the 2–4 true leaf (TL) growth stage, which will provide no control for already emerged weeds. However, Palmer amaranth often emerges between sugarbeet planting and the 2 TL sugarbeet growth stage. Consequently, as of 2023, there were no herbicide options to control Palmer amaranth in sugarbeet …

Proso Millet In Us High Plains Dryland Agriculture: Systems Resilience, Phenology, And Consumer Preferences For Alternative Grains, Pratiksha Baishya

Dissertations and Doctoral Documents, University of Nebraska-Lincoln, 2023–

Dryland crop production in Nebraska's semi-arid High Plains faces challenges from fluctuating weather impacts of climate change, including extreme temperatures, short growing seasons, and recurring droughts. Proso millet is an alternative crop used to build a more robust three-year rotation in the region, rather than the traditional two-year wheat-fallow cycle. This dissertation provides a systems-level assessment of proso millet, a climate-resilient crop with great potential to support sustainable cropping systems in the US High Plains. Using a field-to-consumer approach, it highlights its agronomic and environmental advantages in dryland rotations, develops a phenological framework to aid future research on production, crop …

An Integrated Modeling Framework To Evaluate Circularity Of The Corn–Water–Ethanol–Beef Nexus, Heydi Han

Dissertations and Doctoral Documents, University of Nebraska-Lincoln, 2023–

This dissertation examines the transition from conventional linear agricultural and food bioenergy systems toward more circular, resilient, and resource-efficient configurations. Prior research indicates that spatial and temporal variability in soil, weather, animal biological responses, and management decisions strongly influences productivity, nutrient-use efficiency, and profitability. Studies have also shown that a diversified circular system can buffer these sources of variability, improving stability and adaptive capacity. Building on these insights, the central focus of this work is to develop an integrated modeling framework to evaluate circularity within the Corn-Water-Ethanol-Beef (CWEB) nexus and explore how climate variability and management choices shape system-wide performance. …

Evaluating Fall And Spring Planted Cover Crops For Integrated Management Of Herbicide Resistant Palmer Amaranth And Effect On Soil Health, Vipin Kumar

Dissertations and Doctoral Documents, University of Nebraska-Lincoln, 2023–

Herbicide-resistant Palmer amaranth (Amaranthus palmeri S. Watson) pose a severe threat to agronomic crop productivity in the United States, including corn and soybean production in Nebraska. Therefore, there is an urgent need for diversified and sustainable management approaches. Integrating cover crops (CCs) with herbicide programs represents a promising strategy to achieve Palmer amaranth suppression, sustain crop yields, and contribute to long-term soil health in irrigated corn–soybean production systems in Nebraska.

A meta-analysis of 41 studies and 595 paired observations demonstrated that CCs reduced Amaranthus spp. density and biomass by 37–59% depending on the growing season, with grasses and mixtures …

Assessing Crop Rotation Productivity, Soil Health, And Fertility, And Economic Performance, To Enhance Semi-Arid High Plains Cropping Systems Sustainability, Ezequiel Maria Villamil

Dissertations and Doctoral Documents, University of Nebraska-Lincoln, 2023–

Sustainable crop production in the semi-arid High Plains of Nebraska faces challenges from limited precipitation, high interannual variability, and economic risk. This dissertation investigates the long-term productivity, water use, soil health, and economic sustainability of dryland crop rotations, with emphasis on the role of pulses as alternatives to fallow.

Chapter 1 analyzes nearly three decades (1995–2023) of on-farm data from the High Plains Agricultural Laboratory (Sidney, Nebraska) to compare seven crop rotations, including wheat, corn, millet, sunflower, and field peas. Results showed that wheat–corn–fallow (W–C–F) consistently outperformed traditional wheat–fallow (W–F) and more intensified four-year rotations, providing the highest grain yields, …

Effect Of Planting Date, Insecticide Efficacy, And Hail Injury On Soybean Gall Midge (Resseliella Maxima Gagné) Infestation In Soybean, Natasha Hiromi Umezu

Dissertations and Doctoral Documents, University of Nebraska-Lincoln, 2023–

Resseliella maxima Gagné (Diptera: Cecidomyiidae) is a recently described and economically significant pest of soybean (Glycine max (L.) Merr.) in the Midwestern United States. Since its identification in 2019, this species has become widespread and is now associated with substantial yield losses in parts of the region. Prior to its formal description, orange larvae were observed in soybean associated with plants damaged by hail, suggesting that plant injury may influence infestation. Given the pest’s economic importance, understanding the role of hail injury and developing effective, integrated management strategies are critical for mitigating its impact.

Field studies were conducted to …

Managing Undesirable Vegetation Transitions On The Landscape: A Study Of Perceptions Of Conservation Professionals In Nebraska And Montana, Anubrata Deka, Simanti Banerjee, Theresa Floyd

Cornhusker Economics

In this bulletin, we have provided a descriptive analysis of the perceptions of conservation professionals in Nebraska and Montana, two states where the rangeland ecosystem is facing a large-scale transition from native grasses to invasive trees and grasses. This analysis provides an initial understanding of the different factors that can influence adoption of policy initiatives by conservation professionals. When considered alongside insights into the management behaviors of ranchers—whose productivity and profitability are adversely affected by these transitions—this information helps form a more comprehensive picture of the ecological and economic impacts of UVTs, as well as strategies for their mitigation. In …

Large Scale Deletion And Rebalancing Within The K1c Kafirin Family In Sorghum, Tyler W. Ferris

Department of Agronomy and Horticulture: Dissertations, Theses, and Student Research

Sorghum bicolor (L.) Monech (sorghum) is cultivated as food for humans and livestock and is valued for its low input requirements. However, sorghum grain protein is deficient in the essential amino acid lysine and has poor protein digestibility because of the abundance of proline-rich kafirins that constitute >70% of proteins that form low-digestibility protein bodies. To reduce kafirin expression in the endosperm, and elicit wholesale proteome rebalancing to increase non-kafirin proteins, a single-guide RNA (sgRNA) Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR/Cas9) construct was previously used to target members of the highly-repetitive alpha-kafirin family, k1C in RTx430 sorghum. The …

Plant Nutrient Interactions In High-Yielding Soybean Environments, Victoria Inklman

Department of Agronomy and Horticulture: Dissertations, Theses, and Student Research

Plant nutrient demands and limitations are usually studied individually by nutrient. Here, we investigated how nitrogen (N) limitation in high-yielding soybean environments affects the uptake, removal, and residual of other plant macro- and micronutrients. The objective of this study was to quantify the uptake, removal, and residual levels of soybean macro- and micronutrients under N-limited conditions and to identify nutrient priorities for high-yielding soybean systems. Aboveground plant samples at physiological maturity were collected in 19 high-yielding soybean fields with N limitation across the state of Nebraska. Reference plots with ample N supply were included within each field to compare macro- …

Crop, Soil Nutrient, And Soil Health Responses Within Integrated Crop And Livestock Systems, Alyssa K. Hall

Department of Agronomy and Horticulture: Dissertations, Theses, and Student Research

We evaluated the influences of grazing livestock on crop production, soil nutrients, and soil health indicators of integrated crop livestock systems using three experiments during a seven-yr. period. Objectives were to (1) determine livestock grazing and cropping system effects on crop yield and soil properties across six yr. in corn-soybean (C-S) and wheat-corn-soybean (W-C-S) systems with and without periodic composted manure application, (2) explore seasonal variation in soil nutrient patterns over two yr., and (3) measure residual responses for corn grain yield plus soil health indicators in yr. seven following a six-yr. study. In experiment 1, neither livestock grazing ( …

Development Of A Machine Learning Framework For An Irrigation Decision Support System, Eric Wilkening, Derek M. Heeren, Yeyin Shi, Laila A. Puntel, Guillermo R. Balboa, Abia Katimbo, Kuan Zhang, Precious Nneka Amori, Bruno Lena

Department of Agricultural and Biological Systems Engineering: Faculty Publications

Currently used irrigation scheduling techniques often require significant human intervention and are time consuming, particularly for variable rate irrigation. This research aimed to develop a conceptual framework that incorporates disparate data sources leveraging both mechanistic and machine learning (ML) approaches. The overarching objective is to utilize the growing availability of data and technology to manage irrigation more precisely, which will minimize negative impacts of irrigation on our water resources. An initial irrigation machine learning model was proposed and tested in this study as a key component of an edge-cloud computing and federated learning decision-making framework. The specific objectives were (1) …

Soil Health In Nebraska: Exploring Practitioners' Needs And Insights From A Long-Term Organic Farm, Ingrids Isabel Mata Vigil

Department of Agronomy and Horticulture: Dissertations, Theses, and Student Research

Soil health is foundational to sustainable agriculture, environmental resilience, and long-term food security. Yet, the adoption of soil health assessments remains limited, often perceived as too technical, costly, or difficult to implement in real-world contexts. To better understand these challenges, the first chapter presents findings from a statewide survey of 41 soil health practitioners in Nebraska, including farmers, extension educators, NRCS staff, and conservation professionals. Respondents highlighted the need for simpler, more accessible, and context-specific tools for soil health assessment that help practitioners make informed decisions aligned with their management goals. Complementing these insights, the second chapter includes an independent, …

Evaluating The Effects Of Row Spacing, Legume Intercropping, Fertilizer Source, And Fertilizer Timing On Intermediate Wheatgrass In Eastern Nebraska, Madeline M. Johnston

Department of Agronomy and Horticulture: Dissertations, Theses, and Student Research

Kernza^® is the trademarked name of the perennial crop intermediate wheatgrass (Thinopyrum intermedium). In addition to its potential for dual-use as a grain and forage crop, Kernza is marketed to provide needed environmental services by increasing crop biodiversity, sequestering soil carbon, and reducing nitrate leaching. However, more work is needed in cultivar selection and crop management to increase total grain yields and prevent long-term grain yield decline. Furthermore, research in quantifying and understanding Kernza’s ability to affect soil properties and water dynamics is limited.

Two field experiments were conducted at the Eastern Nebraska Research Extension and Education …

Evaluating Biodegradable Mulch As A Soil Conservation Tool And The Impact On Soil Properties And Yield In Soybean (Glycine Max) Cropping Systems In Eastern Nebraska, Ana Clara Gomes

Department of Agronomy and Horticulture: Dissertations, Theses, and Student Research

This study, conducted during the 2024 growing season, evaluated short-term effects of soil management practices on greenhouse gas (GHG) emissions, soil microclimate, nitrogen dynamics, weed suppression, and soybean (Glycine max) yield. In addition to conventional tillage and no-till, this research included cereal rye (Secale cereale) cover cropping and a novel sprayable biodegradable mulch (BioWRAP®) to assess emerging strategies for sustainable soybean systems under contrasting moisture regimes.

Field trials were established at two eastern Nebraska locations: Havelock (dryland, silty clay loam) and ENREEC (irrigated, clay loam). A strip-block randomized design with four replications tested six soil management …