Agronomic advancements have brought corn yields to new heights, but producers have had little guidance on how to meet the nutrient requirements of modern, high-yield corn hybrids in a way that maximizes their yields, writes Fred E. Below, PhD, Professor of Plant Physiology, Department of Crop Sciences, University of Illinois at Urbana-Champaign, on Agricen.com. As a result, the high yields we see today have been accompanied in many places across the U.S. by a significant drop in soil nutrient levels, particularly phosphorus (P), potassium (K), sulfur (S) and zinc (Zn). This combination — higher yielding hybrids and decreasing soil fertility levels — suggests that producers have not sufficiently matched their maintenance fertilizer applications with nutrient uptake and removal by the corn.
By better understanding nutrient uptake and partitioning, producers can optimize their fertilization practices to meet their crop needs and attain maximum yield potential. I’ll focus here primarily on the uptake, partitioning, and utilization of P and K by corn.
Typical fertilization for corn in the United States is 180 lbs of N, 90 lbs of P2O5 and 160 lbs of K20 per acre, with no S or micronutrients. For modern corn hybrids in high-yielding systems, mineral nutrients with high requirements for production (i.e., nitrogen [N], P, K) or with a high harvest index (HI: the percentage of total plant uptake that is removed with the grain) (i.e., N, P, S, Zn) are important for obtaining high corn yield.