Nutrient Uptake and Partitioning In High-Yielding Corn.

     Comprehensive studies have documented nutrient accumulation and partitioning patterns of hybrids only as recent as 25 years ago.  It is suggested that modern, transgenic insect protected hybrids coupled with improved agronomic practices have influenced the quantity and the timing of nutrient acquisition.  The objective of this study was to investigate nutrient uptake and partitioning among elite commercial germplasm under modern management practices.  Locally adapted hybrid pairs were grown across two site-years in central (Champaign) and northern (DeKalb) Illinois locations in 2010.  Plots were sampled at six growth stages incrementally spaced based on growing degree units.  Total nutrient content was determined among four plant fractions for corn yielding 12.0 Mg ha^-1. 

     Key nutrients for high yield corn production were identified based on nutrient harvest index values and the removal of a given nutrient.  Total nutrients required to produce 12.0 Mg ha^-1 of corn included 23,000, 286, 114, 202, 59, 26, 1.4, 0.6, 0.5, 0.1, 0.08 kg ha^-1 of DW, N, P₂O₅, K₂O, Mg, S, Fe, Mn, Zn, Cu, and B, respectively.  Four nutrients were found to have relatively high harvest index values: P (79%), Zn (62%), N (58%), and S (57%).  These results suggest that a high proportion of total uptake for these nutrients are removed annually and may ultimately lead to soil depletion without accurate maintenance fertilizer applications. 

     A ten day period (V10-V14) resulted in the maximum rates of dry weight production and nutrient assimilation on a per day basis for dry weight (432 kg), N (8.8 kg), P₂O₅ (2.4 kg), K₂O (6.1 kg), Mg (2.2 kg), S (0.6 kg), Zn (14.7 g), Mn (18.2 g), B (3.5 g), Fe (99.6 g), and Cu (1.5 g).  While timing of nutrient acquisition varied considerably among nutrients, some required season- long availability – with more than one-half of total uptake occurred post-flowering for Zn, S, P, and Cu.  Additionally, micronutrients demonstrated more narrow periods of rapid nutrient uptake than macronutrients, especially Zn and B, when greater than two-thirds of nutrient uptake occurred during less than one-third of the growing season.  This reexamination of nutrient use provides opportunities to further improve fertilization rate and application timings as growers continue to achieve greater yields.