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Rescue Nitrogen Application

 

2011 Rescue Nitrogen Application Demonstration

Late-Season Rescue N Applications

2011 Rescue Nitrogen Application Demonstration - Johnston, Iowa

In 2011, Pioneer conducted a rescue N application demonstration in Johnston, Iowa, to determine how late N can be applied and still be effective in boosting yield.


Corn Yield Response to Rescue N Applications

Timing of Rescue Nitrogen Application Demo

Rescue N applications prior to tasseling have proven to be effective at recovering yield.

Illinois study¹: 50 pounds/acre of supplemental N applied to an intentionally flooded area was enough to achieve yields similar to the yields in plots where there had not been excess water.

Indiana study²: N applications of 70 lb N/acre applied at V13 resulted in an economic yield response.

Missouri studies: Showed yield can be recovered with N applications as late as tasseling.


¹ (Torbert et al., 1993)
² (Emmert, 2009)


2011 Rescue N Application Demo

Fungicide Application Schedule

Demo plots were established in 2001 to show the effects of simulated rescue N applications at different growth stages to corn suffering low-N stress.

Plots were planted to corn the previous year and has no N fertilizer applied prior to planting in 2011.

Simulated rescue N applications were conducted at five different timings during the growing season.

N was hand-applied in the form of urea and incorporated along the corn rows.

The demo was for observational purposes only; no yield data were collected.


Stress Symptoms

Stress symptoms apparent in June

Stress symptoms were apparent by late June in plots where N had not been applied.


Nitrogen Stress Symptoms

N stress symptoms in non-treated plot

N stress symptoms in non-treated plot.


Visual Observations - July 27, 2011

V2 and V8 nitrogen applications

The V2 application plot showed a stark contrast in height and greenness compared to the non-treated plot to the left.

Plants in the V8 application plot had similar color to the V2 application plot, but had reduced height throughout the growing season.


Visual Observations - July 27, 2011

V16 and VT nitrogen applications

Plant height was further reduced with each successive application timing due to the longer period of N stress.


Visual Observations - July 27, 2011

R2 application plot and non-treated plot

N was applied to the R2 plot on July 27, so the appearance of plants was similar to that in the non-treated plot at this point.


V2 Application (200 lbs N/acre) - Oct. 28, 2011

Ears in V2 application plot

The study site experienced heat and drought stress during the latter half of the summer.

Ears in the V2 application plot were not completely filled to the tips, which was generally the case in other studies at the location.


V8 Application (180 lbs N/acre) - Oct. 28, 2011

Ears in V8 application plot

Ears in the V8 application plot were slightly smaller than those in the V2 application plot.


V16 Application (100 lbs N/acre) - Oct. 28, 2011

Ears in V16 application plot

Ear size continued to diminish with each successive application timing, reflecting similar trends in plant height and color.


VT Application (80 lbs N/acre) - Oct. 28, 2011

Ears in VT application plot

Ear size continued to diminish with each successive application timing, reflecting similar trends in plant height and color.


R2 Application (50 lbs N/acre) - Oct. 28, 2011

Ears in R2 application plot

Ears in the R2 application plot had substantial portions of the tips unfilled.

Prior research has indicated that R2 is the latest growth stage at which rescue N applications can have a benefit.


Non-treated (0 lbs N/acre) - Oct. 28, 2011

Ears in non-treated plot

Ears in the non-treated plot were typically very small or were only partially filled.

Ears in the R2 application plot appeared to be generally slightly larger than those in the non-treated plot, however this may be due field variability. Visual symptoms of N stress were more severe in the non-treated plot than the R2 application plot in June and early July, even though neither plot had received any N at that point.


Conclusions

Pioneer Agronomy Sciences - Nitrogen Application Timing test plot
  • Rescue N applications can be effective at recovering yield as late as tasseling.
  • The longer plants are subjected to low-nitrogen stress, the greater the eventual yield loss will be.

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