Date of Award

Fall 2023

Document Type

Open Access Dissertation

Department

Environmental Health Sciences

First Advisor

Geoffrey Scott

Abstract

Disregard for soil, an essential natural resource, hinders global food production. Food insecurity is a major concern for both public health officials and environmental scientists due to soil quality decline, pollution, and climate change. Alternatives or targeted additions to chemical fertilizers can bolster soil quality, improve crop yields, lengthen crop shelf life, and mitigate environmental pollution. One potential alternative to chemical fertilizers is replacement of them with biological soil amendments, including algae, to enhance crop growth and improve soil health. Research was conducted at the University of South Carolina-Columbia campus garden to determine impacts of non-toxic freshwater algae on crop growth, seed germination, nutrient content, and post-harvest shelf life. Algal species were selected due to widespread distribution and known ecological properties. The experiments included commercially important food crops, including tomatoes, peas, and potatoes. Results varied highly among different crops. Crops grown with algae generally germinated at higher rates, frequently with taller plants, with increased shelf life, improved soil community structure, and higher nutrient content for some crops. For instance, beets in the treatment groups grown in Supersod soil had 50-100% higher germination rates than those in the Supersod control groups without algal addition. Community structure parameters, as indicated by soil health tests, were also positively impacted by the algal addition to soil, as well as cover cropping. For example, total fungal biomass was twice as high in the spring and summer groups and 4.5 times higher in the second fall group than in the initial fall group. These results are only applicable to the selected algal species and crop varieties. Small sample sizes necessitated nonparametric statistical analysis of metrics between treatment and control groups. Future research should utilize additional algal species and crops as well as many more replicates per crop. Tests with different soil types would bolster knowledge and comprehension of soil amendment mechanisms. Molecular testing also should be conducted to elucidate how soil amendments alter soil microbe gene expression. Future research should also address the ability of algal additions to further enhance the shelf life of conventionally grown crops to prevent spoilage from harvest to consumers’ plates.

Rights

© 2024, Lala Christina Ek

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