Seed Nutrient Concentration Differences among High- and Average-Yielding Areas of Soybean Production in Arkansas

Continued increases in average soybean [Glycine max (L.) Merr.] yield will depend on decreasing the yield gap, defined as the difference between current and potential yield, which is the yield of a cultivar grown with the best technologies without limitations on nutrient and water availability and with biological stresses effectively controlled. Research in annual state yield contest fields can provide critical information about yield potentials and plant response differences between ultra-high and average producing areas. Therefore, the objective of this study was to assess seed concentration differences between high- and average-yield areas across soybean growth stages. During the 2015 growing season, in each of seven regions of the “Grow for the Green” yield contest in Arkansas, one contest-entered, high-yield (HY) area in close proximity to one average-yield (AY) area were plant-sampled at the mid-R5, mid-R6, and harvest maturity (HM) growth stages. Grain yields in AY areas ranged from 40 to 98 bu ac-1 (2688 to 6585 kg ha-1; 13% moisture) and averaged 69 bu ac-1 (4664 kg ha-1), while yields in HY areas ranged from 42 to 109 bu ac-1 (2822 to 7324 kg ha-1) and averaged 82 bu ac-1 (5647 kg ha-1). Among all growth stages and yield areas, seed potassium (K) concentration was greatest (P < 0.05) in HY areas at mid-R5 across regions 1.95% (19.5 g kg-1). Averaged across growth stage, seed boron (B) concentration was greater (P < 0.05) in HY 31.76 ppm (31.76 mg kg-1), while seed carbon (C) concentration was greater (P < 0.05) in AY areas (48.9%; 489 g kg-1) across regions. Averaged across yield area, seed P, Ca, Fe, Mn, Zn, Cu, and B concentrations were at least 9% greater (P < 0.05) at mid-R5, while seed N concentration was greatest (P < 0.05) at HM (5.76%; 57.6 g kg-1) than at the other two growth stages. Results of this study demonstrated differences in seed nutrient concentrations across growth stages between HY and AY areas that can be used by producers to maximize soybean yields in all production scenarios.