Theses and Dissertations

Issuing Body

Mississippi State University

Advisor

Shanmugam, Shankar

Committee Member

White, Joshua

Committee Member

Harvey, Lorin

Committee Member

Cox, Michael

Date of Degree

8-7-2025

Original embargo terms

Visible MSU Only 1 year

Document Type

Graduate Thesis - Campus Access Only

Major

Agronomy (Plant and Soil Sciences)

Degree Name

Master of Science (M.S.)

College

College of Agriculture and Life Sciences

Department

Department of Plant and Soil Sciences

Abstract

A field study was conducted from 2023 to 2024 at Pontotoc, Mississippi, to evaluate the effects of cover crops and nitrogen (N) fertilizer on soil microbial communities in sweet potato production. The study followed a randomized split-block design with three cover crops (Clover, Wheat, and Fallow) and three N rates (0, 50, and 100 lb N acre⁻¹), each replicated four times. Soil samples were collected at cover crop termination, sweet potato planting, and harvest. Bacterial and fungal communities were analyzed using Illumina HiSeq sequencing. Soil properties such as total carbon, total nitrogen, pH, POXC, and microbial activity (AWCD) were also measured. Cover crop and nitrogen treatments affected microbial diversity and soil properties. Clover plots had higher carbon, nitrogen, and labile carbon levels, supporting greater fungal diversity. Bacterial communities responded more to nitrogen fertilizer, especially early in the season, while fungal communities were more influenced by cover crop treatments. Proteobacteria and Actinobacteriota were the dominant bacterial phyla, and Ascomycota dominated the fungal groups. Overall, integrating legume cover crops with balanced nitrogen application improved soil health by enhancing microbial diversity and activity.

Sponsorship (Optional)

MAFES - Pontotoc, IGBB

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