Are Nutrient Deficiencies Limiting High Yield? Tissue and Soil Analyses of North Carolina Corn Yield Contest Entries.

Some NC corn growers think nutrient deficiencies are limiting yield, especially under irrigation. They question whether NC Dept. of Agriculture and Consumer Services (NCDA&CS) fertilizer recommendations are adequate for high-yielding hybrids and management. While NC Corn Yield Contest leaders have attained 18.8 to 21.9 Mg ha^-1, recent world-record yields, 31.6 Mg ha^-1 in Georgia and 33.4 Mg ha^-1 in Virginia, were in environments and soils similar to ours, hence NC yield potential is similarly high. We’re adding value to the NC Yield Contest by studying tissue and soil of Contest entries to determine whether nutrient deficiencies become apparent at high yield, and if nutrients need to be within established sufficiency ranges. We created a Study website and a Qualtrix enrollment survey.  We sent 510 postcard invitations to recent contest entrants, and emails to the 13 NCDA&CS Regional Agronomists and 110 NCES field agents, plus 134 professionals from the tri-societies “Find a Professional |Search”. Forty-five growers, seven agronomists, ten agents, five consultants, and two “other” enrolled. Most agronomists/agents/consultants agreed to recruit and work with >1 grower. From Contest areas, tissue and soil were sampled at VE-V2, V10, VT-R1, and R6. We offered to sample/assist, but all participants agreed to follow website instructions, complete pre-filled/prepaid forms, and submit to NCDA&CS, which agreed to grower fees (soil=$0, tissue=$5) rather than research fees ($5, $12). As of August 1, ~119 plant and ~86 soil samples had been submitted, but participants could conserve/send all samples at R6. We will determine relationships among: tissue and soil nutrients; nutrient-use efficiency; soil type; and management gleaned from Contest entry forms.  The study may demonstrate whether high yield is achievable despite tissue and/or soil tests that appear insufficient, and provide valuable information regarding sufficiency ranges, soil-test calibration, and whether/which adjustments may be needed in order to prioritize research appropriately.