Date of Graduation

5-2026

Document Type

Thesis

Degree Name

Bachelor of Science in Agricultural, Food and Life Sciences

Degree Level

Undergraduate

Department

Crop, Soil and Environmental Sciences

Advisor/Mentor

Dr. Kristofor Brye

Committee Member

Dr. David Miller

Second Committee Member

Dr. Lisa Wood

Abstract

Phosphorus (P) is an essential nutrient needed in agriculture for proper plant growth and development and is often introduced into agricultural systems in the form of synthetic P fertilizers. Mined rock phosphate is the primary P source for the production of synthetic P fertilizers and is a finite resource. Struvite (MgNH4PO4·6H2O) is a compound that can be precipitated from municipal wastewater, recovering P, and is currently being evaluated for its potential use as an alternative fertilizer-P source. The objective of this study was to evaluate the effects of fertilizer-P source [i.e., synthetic electrochemically precipitated struvite (ECSTsyn), real-wastewater derived ECST (ECSTreal), chemically precipitated struvite (CPST), and monoammonium phosphate (MAP)], soil (i.e., Fragiudalfs, Hapludolls, Udifluvents, and Fraglossudalfs), and water source (i.e., rainwater, groundwater, and struvite-removed real wastewater) on micronutrient concentrations in runoff water from laboratory rainfall-runoff simulations. Concentration changes in runoff K, Na, Mn, Zn, and Cu were not attributed to fertilizer-P source (P > 0.5) but rather significant (P < 0.05) water-soil interactions. Runoff concentration changes for K and Na differed significantly from zero (P < 0.05) among water source-soil combinations, with runoff K concentrations ranging from −21.9 to 0.30 mg·L⁻¹ and Na concentrations ranging from −7.46 to 0.25 mg·L⁻¹. Runoff concentration changes in Mn, Zn, and Cu did not differ significantly from zero across most water source-soil combinations or were relatively small (< 0.12 mg·L⁻¹) suggesting neither struvite nor the well-characterized MAP treatment meaningfully contributed significant concentrations of potentially toxic micronutrients to runoff. Monoammonium phosphate was the only fertilizer-P source to produce a significant change in runoff S concentration (0.20 mg∙L-1) while changes in S concentration from CPST (0.04 mg·L⁻¹), ECSTreal (−0.02 mg·L⁻¹), and ECSTsyn (−0.03 mg·L⁻¹) did not differ significantly from a change of zero. The similarities in micronutrient responses between MAP and struvite treatments suggested potential parallels in fertilizer-P source behavior within an agroecosystem. Further supporting experimentation at the field scale is needed to continue characterizing struvite as a potentially viable, alternative fertilizer-P source.

Keywords

struvite; soil science; runoff; micronutrients; phosphorus fertilizer; alternative fertilizer

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