Soybean nutrient uptake and partitioning models are primarily built from work conducted in the 1960s; however, recent work highlighted the need for large increases in soybean nutrient uptake recommendations. This and other work indicate a critical need to update recommendations for today's soybean varieties, production practices, climate, and economics. All agronomic inputs (biologicals, plant growth regulators, fungicides, etc.) and economic thresholds are based on crop growth stage; however, with larger farms, scouting has become increasingly cumbersome. Plant phenology models have not been validated in the variable climate of the north central Corn Belt.

This large-scale investigation...