February 3, 2022
The optimum nitrogen (N) rate for corn can be difficult to determine for farmers. Inadequate N can cause a noticeable reduction in yield, whereas excess N can go unused. A balanced use of nitrogen (N), according to crop demands, is necessary to reduce N loss in the environment, reduce excessive vegetative growth of corn plants that can result in increased vulnerability to lodging, and increase the return on N investment.
The objective of this trial was to evaluate the effects of N rates on corn.
Research Site Details
|Soil Type||Hord silt loam|
- The trial design was a split-plot with N fertilizer as the whole plot and corn product as the subplot with four replications.
- A total of six N rates and three corn products were selected for this trial.
- N Rates: 0, 60, 120, 180, 240, and 300 lb/acre.
- Corn products: 113 RM, 115 RM, 113 RM-2
- The nitrogen fertilizer used was 32-0-0 and it was applied using a 360 Y-DROP on 06/29/2021.
- Weeds were uniformly controlled with herbicides and no other pesticides were applied.
- Test weight, moisture, and total shelled weight were collected to calculate yield.
- The grain yield was corrected to a standard of 15% moisture content.
Understanding the Results
- Plant lodging was high at higher N rates as observed in Figure 1.
- For corn, plant lodging increased as the N rate increased, especially at and above 120 lb/acre, except for the corn product 115 RM (Figure 2).
Figure 1. Plant lodging of corn at higher N rates. Pictures were taken on 11/15/2021 at the Water Utilization Learning Center in Gothenburg, Nebraska
Figure 2. Nitrogen fertilization treatments in corn. Pictures were taken on 09/10/2021 at the Water Utilization Learning Center near Gothenburg, Nebraska.
- Lodging percentages did differ with different corn products (Table 1).
- The greatest corn grain yield increase was observed in response to an incremental increase of N from 0 to 60 lb/acre and was observed across all corn products in this study (Table 2).
- There were no positive statistical differences in corn grain yield when N rates applied were above 120 lb/acre in this trial. Instead, two of the corn products had reduced yields because of excess lodging.
Table 1. Average lodging of corn products according to nitrogen rates. *LSD (least significant difference) calculated as part of a larger trial containing 6 corn products
Table 2. Average grain yield of corn products according to nitrogen rates. *LSD (least significant difference) calculated as part of a larger trial containing 6 corn products
- Higher nitrogen rates lead to excessive lodging which reduced harvestable yield. This can be especially true in fields that are corn-on-corn where there are other factors degrading the integrity of the stalk such as disease.
- Carefully matching nitrogen rate with corn product, yield potential and residual soil nitrogen is key to maximize potential benefit of N fertilizer while minimizing potential drawbacks.