Date of Graduation

5-2023

Document Type

Thesis

Degree Name

Master of Science in Biological Engineering (MS)

Degree Level

Graduate

Department

Biological and Agricultural Engineering

Advisor/Mentor

Marty Matlock

Committee Member

Greg Thoma

Second Committee Member

Ebenezer M Kwofie

Keywords

Corn;Crop Modeling;Environmental Impact;Life Cycle Assessment;Pesticides

Abstract

In recent years there has been increasing interest in reducing agricultural environmental footprints in the United States, particularly for commodity crops like corn grain. Pest management is one aspect of agricultural production that is often identified as having potential for improvement with regard to environmental impact, but there is not a robust body of literature to identify the wide-scale influence of pesticides on yield and environmental impact. In this study, we hypothesized that the use of different classifications of pesticides has a significant impact on the overall environmental impact. To test this, agricultural models were created to represent the dominant corn production practices across the US to test how much the usage of pesticides, and the changes in field operations that they enable, impact the overall environmental impact of corn production for the US as a whole. Treatment scenarios were devised to represent corn production without chemical controls for pests: one for simulating mechanical control of weeds without herbicides, and two for simulating crop production impacts of insect and disease without the use of insecticides and fungicides, respectively. The field data produced by the models was combined with pesticide and yield data from the Federal LCA Commons and the National Agricultural Statistics Service to create life cycle inventories of each model for each scenario. These inventories were then analyzed in the SimaPro life cycle assessment using the Impact World+ to assess the environmental impact values across a number of mid- and Mid-point environmental impact categories. The results were assessed for significant differences using either an ANOVA and Tukey test or a Kruskall-Wallis and Dunn test, depending on whether the impact data was normally distributed or not. Our analysis revealed that there was a significant difference between the baseline scenario and at least one of the treatment scenarios for every environmental impact category. The NoWeedCont and NoInsectCont scenarios had significantly higher mean impact values for every impact category. The NoDiseaseCont scenario mean impact values were significantly higher than the baseline scenario for eight impact categories and not significantly different for most of the others. The only instance of a treatment scenario having a significantly lower mean impact value was for the ozone layer depletion impact category in which the NoDiseaseCont scenario had a significantly lower mean impact value. The primary driver behind the difference for many of the impact categories was the yield penalty imposed due to not using chemical controls for pest pressure and the difference in operations between the treatment scenarios and the baseline. Our analysis suggests that removing pesticides from the corn production process without taking other steps to mitigate yield loss due to pests is not a viable strategy to reduce the environmental impact of US corn production. There are a multitude of avenues for further inquiry on the interplay between pest management and environmental impact, and this study provides a baseline of environmental impacts for the dominant corn production practices within the US that can be used in future research.

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