Table 1. Total macronutrient and micronutrient uptake and removal in Urbana, IL and DeKalb, IL (2010) for corn averaging 230 bushels/acre. Harvest index was calculated as the ratio between nutrient removal with grain and total nutrient uptake and is reported as a percent.

Nutrient contents were determined at six growth stages among four plant fractions (leaf, stalk, reproductive, and grain tissues). To view a powerpoint which details this sampling and partitioning process, click here.

When developing fertilizer recommendations, two major aspects of plant nutrition are important to understand and manage high yield corn production: 1) the amount of a given mineral nutrient acquired during the growing season, or ‘total nutrient uptake,’ and 2) the amount of that nutrient contained in the grain, or ‘removed with grain’ (Table 1).

Further improving fertility practices require matching in-season nutrient uptake with availability of nutrients. For some nutrients (e.g., N, K, Mg, Mn, B, and Fe), as much as two-thirds of total uptake occurs during vegetative growth (Figure 1). Of critical importance is supplying N to meet corn’s peak needs of 7.8 lb N/day from V10-V14. Uptake of N does not cease at VT/R1 since as much of 50 lb N/acre is accumulated and partitioned directly into the developing seeds during grain fill (Figure 1).

Contrary to nutrients like N and K, nutrient accumulation of P, S, Zn, and Cu is equally distributed between vegetative growth and during reproductive growth (i.e., ear development and grain-fill) . Season-long supply of P, S, Zn, and Cu is imperative as we strive to maximize corn yields. Relative to total uptake, P is removed to a greater extent than any other nutrient (Table 1). Agronomic practices which do not adequately replace removed P may eventually lead to a depletion in soil fertility levels.