College of Agriculture & Natural Resources Department of Plant, Soil and Microbial Sciences

Final Thesis Defense Crop and Soil Science M.S. Degree: SPENCER FLEMING

November 14, 2025 10:00AM - 11:00AM

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Room A 271 PSSB

Members of the Examining Committee and their Department:

1. Dr. Kurt Steinke - Plant, Soil and Microbial Sciences

1. Dr. Zachary Hayden – Horticulture
2. Dr. Christina DiFonzo – Entomology

ABSTRACT

Variable weather and volatile fertilizer pricing are impacting MI soybean producers creating a need for a cost-effective soybean nutrient management strategies. Two multi-year field trials were conducted involving two planting dates (regular and late) and multiple fertilizer strategies (pre-plant K, starter fertilizer, micronutrient foliar fertilizer, and intensive management). Vegetation indices, grain yield, grain quality, and economic return were evaluated. Planting date had little impact on soybean yield and profitability during this study. With sufficient soil micronutrients, foliar fertilizer demonstrated few impacts. Pre-plant K had few short-term impacts but due to the time required to increase STK concentrations producers should consider K applications based on soil test values. Starter fertilizer showed potential for increasing soybean yield due to the conditions encountered during this study.

A combination of variable weather, and the implementation of the early harvest campaign has created a gap in knowledge for sugarbeet producers to manage N strategies with regards to harvest intervals. Two multi-year field trials were conducted to evaluate two starter N fertilizer rates, and two sidedress N fertilizer rates across early June, July, and August on early and conventional harvest timings. Starter fertilizer increased root yield across harvest intervals and years except for early harvest 2023. Starter N fertilizer was not beneficial for sucrose concentration. Late season N (August SD) was a greater risk to root yield than sucrose concentration. The presence/absence of early season moisture was the most impactful for late season N to impact yield and economic return. Further research is required to evaluate N strategies across harvest intervals, due to environmental conditions creating variability.

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