How Important Is Uniform Emergence in Corn.

Producer experience suggests that increasing corn yield depends on uniform emergence and rapid growth from emergence to V6.  Field studies in 2014 in North Carolina found that plants that emerge 12 to 14 hours later than the majority of plants in the field are smaller and have significantly less yield potential.  This observation may explain why management practices consisting of starter fertilizer and/or a fertilizer seed treatment have shown consistent results in achieving greater yield compared to managing corn without an early fertilizer treatment.  It is clear that one key to improving corn yield lies in a better understanding of the impact of quick, uniform emergence on corn growth and yield and the identification of management practices that enhance better emergence and early growth. To examine the question of the impact of quick, uniform emergence on corn growth and yield two field sites were in North Carolina were chosen based on differing soil types.  At each site four treatments were applied to test emergence. These consisted of a standard check treatment with starter fertilizer applied in a 2 x2 band and corn planted at a standard depth of 3.8 cm, a treatment where corn is planted at 3.8 cm depth without starter fertilizer, a treatment with corn planted at a depth of 6.4 cm, and a treatment with corn planted at 7.6 cm.  In a 6-m section of row plants were marked on the day they emerged.  At VT stalk diameter and plant height were measured and at maturity these same plants were hand harvested to determine ear weight and yield.  Corn plants that emerged later when compared to the plants that emerged initially were significantly shorter and had thinner stalks.  Ears from these late emerging plants were shorter with fewer kernels resulting in significantly less ear weight and yield.