Michigan spring weather variabilities and earlier planting dates may provide opportunities for starter fertilizer to influence early-season soybean (Glycine max L. Merr.) dry matter production while simultaneously decreasing the time interval for nutrient accumulation. However, potential fertilizer impacts on inhibition of biological N fixation (BNF) are not well understood. Two multi-year field trials investigated the effects of planting date, starter fertilizer, and various nitrogen (N) application timings on BNF, grain yield, and expected net return on irrigated and non-irrigated environments. April planting as compared to May increased grain yield in only one of four site years. Starter fertilizers containing < 28 kg N ha-1 did not negatively influence BNF, while treatments containing 112 kg N ha-1 saw significant BNF contribution reductions. Grain yield was influenced by fertilizer strategy in one of four site years, but none of the evaluated fertilizer treatments exceeded profitability of the non-treated control.Over-winter climate variability in Michigan has become an unpredictable freeze-thaw cycle that impedes the viability of sugarbeets stored in outdoor piles. Adjusting cultural and nutrient management of both early and regular harvest timings may generate greater sucrose production with less overall tonnage. Two multi-year field trials were established to evaluate two opposing cultivars, two N rates, and liquid potassium on early and conventional harvest timings. A high tonnage cultivar produced greater yield and recoverable sucrose during early harvest than a cultivar with moderate tonnage levels but good disease resistance. Sucrose and tonnage were maximized by the split-applied (179 kg ha-1) N rate for both harvest timings in both site years. Surface-banded liquid potassium applied in early July did not influence yield or recoverable sucrose in either site year. Further research is supported by the interaction of cultivar selection, N rate, and harvest timing.℗
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