Evaluation of Nitrogen Rate for Corn in Eastern Missouri

Rationale and Objectives

  • Trials were conducted in eastern Missouri in 2013 to evaluate corn yield response to additional nitrogen (N) application beyond normal grower rates.
  • In 2013, the extremely wet spring coupled with an abnormally dry, late summer allowed for evaluation of yield response to N rate in these conditions.

Study Description

Plot Layout:      Field-length strips
Locations:    16 locations across eastern Missouri
    Hybrid: 4 hybrids per location. 7 total
hybrids used across all locations
(CRM range 103-116).
    Population: 30,000, 34,000 and 38,000 plants/acre. 
    Nitrogen Rate:   Grower standard rate
      Grower standard rate + 50 lbs/acre additional N
Analysis: In-season observations were performed in fields as
well as the use of NDVI imagery. Yield monitor data from
these plots were analyzed in Pioneer® Field360™ Studio
software to remove common sources of monitor error.


Figure 1: Corn yield response to additional N in Missouri locations.
  • Yield responses to additional N varied across locations (Figure 1).
  • When averaged across all locations, there was a 6 bu/acre yield advantage to adding 50 lbs of N above grower standard rates.
  • Most locations experienced heavy rainfall in the spring right after planting, which could have lead to possible N loss. Some of the locations also experienced drier than normal conditions late in the season, which could have impacted N uptake.

Figure 2. Average corn yield response to additional N among early maturity hybrids (103 to 109 CRM) compared to late maturity hybrids (112 to 116).


Average corn yield response to additional N tended to be greater with earlier CRM hybrids
(Figure 2).

  • Yield response to additional N ranged from 5-8 bu/acre (average 7 bu/acre) for hybrids in the 103 to 109 CRM range.
  • Hybrids in the 112 to 116 CRM range had a flat to slightly negative response to additional N (average -2.5 bu/acre)
  • A possible reason for this is that there was less soil mineralized N available to the growth cycles of the earlier CRM products versus the fuller CRM products, which may have been able to more effectively uptake mineralized N from the soil because of their late-season plant health and growth cycle.

Figure 3. Average corn yield response to additional N by plant populations.

  • Yield response to additional N did not differ greatly among populations (Figure 3). Average yield response was slightly greater at 34,000 plants/acre (3 bu/acre) than at 30,000 plants/acre (1 bu/acre) or 38,000 plants/acre (0.5 bu/acre).

Management Suggestions/Conclusions

  • While higher N rates resulted in higher yields at some locations, management decisions need to consider economics as well as operation yield goals.
  • Hybrid by N rate interactions were observed, but further testing should be done before using this information as a management suggestion.
  • As seeding rates increase to meet yield goals, careful attention should be made to ensure that N rates are aligned with those same objectives.
  • N management is only 1 component to yield. When other yield-limiting factors exist (such as too little moisture), additional N applications may not result in a positive response. 

PIONEER® brand products are provided subject to the terms and conditions of purchase which are part of the labeling and purchase documents. 2013 data are based on average of all comparisons made in 17 locations through December 1, 2013. Multi-year and multi-location is a better predictor of future performance. Do not use these or any other data from a limited number of trials as a significant factor in product selection. Product responses are variable and subject to a variety of environmental, disease, and pest pressures. Individual results may vary.