Responses to Side-Dressed Nitrogen - Iowa


  • Pioneer is interested in helping customers get the most out of their nitrogen (N) investment.
  • In 2013, Pioneer field agronomists conducted a series of studies to understand the value of side-dressed or in-season N applications.

Study Description

Locations: 30 on-farm locations
Hybrids: Results are pooled across 48 hybrids
Populations: 30,000 34,000
(plants/acre) 38,000 42,000
Treatments: Farmer standard N management
Farmer standard plus 50-75 lbs/acre side-dress N application
Photo: Corn field with side-dressed N

At this high-yielding location, side-dressed N seemed to reduce late-season lodging. Left: Farmer standard. Right: Side-dress N

Results and Conclusions

  • Farms in Iowa received abnormally high rain fall in late April and early May. This created conditions favorable for loss of fall or preplant applied N.
  • The yield advantage by locations is shown in Figure 1.
  • >Side-dress N modestly improved the response to plant population in environments yielding between 150 and 200 bu/acre Figure 2.
  • At locations yielding more than 200 bu/acre, side-dress N strips were at a higher yield level across populations.
  • Extreme drought and heat from silking through grain fill most likely limited yield responses to side-dress N.
  • Despite the unusually dry summer, this research demonstrates the value of side-dress and in-season N applications.

Figure 1. Yield advantage with the addition of a side-dress N
application. n = 30 locations

Chart: Yield advantage with the addition of a side-dress N application

Figure 2. Corn yield response to population and side-dressed N at 
locations yielding between 150-200 bu/acre. n = 11 locations and 
17 hybrids.

Chart: Corn yield response to population and side-dressed N at locations yielding between 150-200 bu/acre

Figure 3. Corn response to population and side-dressed N at locations
yielding greater than 200 bu/acre. n = 16 locations and 28 hybrids.

Chart: Corn response to population and side-dressed N at locationsyielding greater than 200 bu/acre


2013 data are based on average of all comparisons made in 27 locations through November 25, 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.