The use of best management practices allow some soybean fields in NC to yield 70 bu/A or more, which is double the historical statewide average yield of 35 bu/A. Due to intensive management, usually these fields present adequate levels of soil nutrients and subsequently, the official recommendations of fertilizers for NC soils point to small or null rates of fertilizers, regardless of yield expectations. In an ongoing project sponsored by the NC Soybean Producers Association, we are refining the recommendations of P and K for high-yielding soybeans. In this proposal, we aim to field test supplemental fertilization strategies, at planting (starter N, S, and P) and during reproductive stages (N and micronutrients). The supplemental fertilization strategies will be compared with the standard fertilization program recommended by NCDA&CS using an economic analysis. We will perform this research in eight site-years, four sites in 2021 and four sites in 2022. We will measure yield, soil nutrient levels, nutrient uptake,and nutrient exported in the grain. We are requesting financial support to partially fund salaries(technician and hourly labor), field supplies, travel costs, and, soil and plant analysis associated with the project.

1. Determine the effectiveness of a supplemental fertilizer phosphorus, sulfur, and nitrogen at planting for North Carolina high-yielding soybeans fields;

2. Determine the effectiveness of a supplemental fertilizer program with foliar feeding with nitrogen and micronutrients applied during the reproductive growth stage (R2) for North Carolina high-yielding soybeans fields;

3. Perform an economic analysis to determine the cost/benefit of each fertilizer strategy, comparing them with the official fertilization program recommended by NCDA&CS.