Graduation Term

Spring 2026

Degree Name

Master of Science (MS)

Department

Department of Agriculture

Committee Chair

Fanson Kidwaro

Committee Member

Robert Rhykerd

Committee Member

Nicholas Heller

Abstract

Compost application is increasingly recognized as a sustainable soil management practice that enhances soil health and crop production. However, the method of application, incorporated versus surface applied, may influence its effectiveness in improving soil properties and crop productivity. This study evaluated the effects of compost application method on soybean (Glycine max L. Merr.) yield and soil health at Illinois State University Research Farm in Lexington, Illinois, across two growing seasons, 2024 and 2025. The 2024 experiment used a Completely Randomized Design comparing incorporated versus surface-applied compost (n = 4; 8 plots). The 2025 experiment used a Randomized Complete Block Design with an untreated check (n = 4; 12 plots). Data were analyzed using PROC MIXED (SAS 9.4) with Tukey-Kramer pairwise comparisons at α = 0.05. No significant treatment effects were detected in plant height, pod number, seed moisture, and grain yield. Year was the dominant source of variation for most agronomic variables. In contrast, both compost treatments significantly improved soil health relative to the check. Soil cation exchange capacity (CEC), sulfur, and boron were significantly elevated under both compost treatments (p < 0.05), and the incorporated treatment additionally produced a significant increase in copper. No significant differences were found between incorporated and surface-applied treatments for any variable, indicating equivalent effectiveness of both methods. This study demonstrated that compost amendments can significantly improve soil health parameters, particularly CEC, sulfur, boron, and copper, while short-term yield benefits may not be immediately observed. These findings highlight the importance of evaluating soil health improvements alongside yield responses when assessing organic amendment strategies for sustainable soybean production.

Access Type

Thesis-Open Access

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