Choosing the Right Components to Maximize Hybrid Yield Potential in Corn Cropping Systems.

The key to maximizing yield is to fit the genetic potential of the plant, in this case a corn hybrid, to the environment it is grown in.  As corn breeders seek to increase genetic potential they introduce hybrids with characteristics such as improved water use efficiency and better root growth that perform best when specific management practices are used.  The result is that new hybrids depend on growers using just the right combination of management practices and rates (seeding or N rates) to realize the yield benefits inherent in these hybrids.   All of the major corn seed companies recognize the importance of combining hybrid genetics with a specific management system to achieve the yield gains necessary to meet the growing demand for corn in the 21^st Century. While most public and private research studies do a good job of examining individual management practices such as seeding rate or whether or not to use a starter fertilizer these single factor studies are not useful in determining the complete set of management practices that need to be implemented for a particular hybrid.

The overall goal of this research is to identify the best hybrid and supporting management practices to maximize yield on a range of soil and environmental conditions in North Carolina.  Particular objectives are 1) To determine how much management components such as new hybrids, plant population, advanced starter fertilizers, N rates, fungicides, and tillage contribute to increasing corn yield in different regions of North Carolina, and 2) to identify the combination of management practices and levels of inputs such as seeding rate and fertilizer which are required to maximize yield for hybrids commonly grown in North Carolina.

Eight studies were initiated in 2012 and 2013 in different environmental regions of North Carolina. A set of five management factors were tested in an experimental design that allowed for the practices to be evaluated as a complete system and for each practice to be evaluated for its contribution to yield in the total system.  The five management factors were: 1) Hybrid - DKC68-05, DKC64-69, Pioneer 1498, Pioneer 1690, Pioneer 2088, and Syngenta N68B-3111, 2) Population - 33,000 vs 43,000 plants per acre, 3) Starter - advanced starter (10-27-0 in a 2 x 2 band plus 3-18-18 applied in-furrow) vs only 10-27-0 applied in a 2 x 2 band , 4) Nitrogen source (2012) or Nutrient seed treatment (2013), and 5) Fungicide – Quilt applied at V5 and VT vs no fungicide.  Standard practices were used for weed control and with 230 lbs of total N applied to the plots at either planting or at V5.  Plots were harvested with a combine with a yield monitor and moisture, test weight and grain yield were recorded.

Across most of the hybrids tested the yield from the plots with the complete package of advanced crop management practices which included 43,000 plants per acre, both an in-furrow and 2 x 2 starter fertilizer, extended release N or nutrient seed treatment, and fungicide was significantly greater than that achieved by the standard system with 33,000 plants per acre, no starter, 30% UAN, and no fungicide.  In the advanced management system multiple hybrids at several sites had recorded yields of 18.8 Mt ha^-1 (300 bu acre^-1) or higher. In no case did the standard practices reach this yield level. The crop management factor which produced most of the increase in yield was the change from 33,000 plants per acre to 43000 plants per acre. In seven site-years the use of the higher population resulted in significantly greater yield compared to the standard practice.  The second most important management factor was the use of the two starter fertilizers.  The other factors tested in this study, extended release N, nutrient seed treatments and fungicide did increase yield in some site-years with some hybrids but did not consistently increase yield across environments or genetics.