Agronomy and Horticulture, Department of

 

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

First Advisor

Christopher Proctor

Committee Members

Daran Rudnick, Bijesh Maharjan, Rodrigo Werle

Date of this Version

7-2025

Document Type

Thesis

Citation

A thesis presented to the faculty of the Graduate College at the University of Nebraska in partial fulfillment of requirements for the degree of Master of Science

Major: Agronomy

Under the supervision of Professor Chris Proctor

Lincoln, Nebraska, July 2025

Comments

Copyright 2025, Ana Clara Gomes. Used by permission

Abstract

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 systems: conventional tillage, no-till, fall-planted rye terminated at planting, spring-planted rye, late-terminated rye (V4 stage), and BioWRAP®.

Measured variables included cumulative CO₂ and N₂O fluxes, soil temperature and moisture (0–10 cm), weed density, nitrate (NO₃⁻) concentration, and yield.

At the Havelock site, no-till significantly reduced CO₂ emissions, and BioWRAP® lowered N₂O emissions relative to other treatments. At ENREEC, GHG emissions did not differ among treatments. Soil temperature and moisture varied over time but showed no consistent treatment effects.

Weed density was lowest under BioWRAP® and late-terminated rye, indicating effective suppression. BioWRAP® and no-till also resulted in higher nitrate levels at harvest, suggesting improved nitrogen retention.

Soybean yields did not differ significantly among treatments at either site, indicating that conservation-oriented practices can reduce environmental impacts without compromising productivity.

These results underscore the value of integrating conventional and novel management strategies—such as no-till, cover crops, and biodegradable mulches—to improve nitrogen use efficiency and suppress weeds in soybean production. While short-term environmental benefits were observed, further research is needed to evaluate long-term effects and scalability across diverse agroecosystems.

Advisor: Christopher Proctor

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