Date Approved
8-20-2025
Graduate Degree Type
Thesis
Degree Name
Biology (M.S.)
Degree Program
Annis Water Resources Institute
First Advisor
Dr. Kevin Strychar
Second Advisor
Dr. Douglas Haywick
Third Advisor
Dr. Chelsea Duball
Academic Year
2024/2025
Abstract
Soil is the largest natural resource on Earth, providing habitat for many organisms and supplying others with food. However, increased anthropogenic activities have led to decreased soil quality due to increased erosion of topsoil or loss of soil structure from agricultural practices and the introduction of pollutants from industrial activities. To improve soil fertility and crop yield, some producers have shifted to using organic fertilizers to increase organic matter and nutrients in the soil, aiding in plant growth. However, there is the potential of introducing heavy metals, such as arsenic and cadmium, and harmful bacteria, like Escherichia coli (E. coli). This thesis focused on using pumpkins (Cucurbita pepo) as an organic fertilizer and how applying them to fields in Michigan affected nitrate, phosphate, potassium, arsenic, cadmium, and E. coli concentrations in soils. Samples were collected from a farm in Oceana County, Michigan, and tested for all parameters using Environmental Protection Agency (EPA) methods for nutrients, metals, and E. coli, with an additional method of imaging flow cytometry (IFCM) for E. coli. Results from this study indicate that soil nitrate levels had the most significant changes after organic pumpkin fertilizer (OPF) application in all fields. Phosphate and potassium concentrations were unchanged. All nutrient content was significantly higher in the topsoil compared to lower depths, suggesting that OPF provided more nutrients to the upper horizon. Arsenic and cadmium concentrations were not significantly different when comparing soil before and after OPF application. This suggests that current concentrations are from natural sources. Concentrations of E. coli were relatively low after OPF application; however, contamination occurred in areas where OPF was applied in dense layers, providing an ideal habitat for bacterial growth and reproduction. Overall, this thesis provides agricultural producers information about pumpkins, their use as an organic fertilizer, and the possible risks and rewards they may have to the soil if used as a fertilizer. Producers can use this information to aid decision-making and improve their agricultural techniques.
ScholarWorks Citation
Anderson, Katelyn R., "Impacts of pumpkins (Cucurbita pepo) as an organic fertilizer on nutrient, heavy metal, and Escherichia coli (E. coli) concentrations on the soils of a West Michigan farm." (2025). Masters Theses. 1164.
https://scholarworks.gvsu.edu/theses/1164
