Side-dressing Nitrogen in Corn
A fertility strategy that worked well in 2013 was side-dressing nitrogen (N) in corn. Side-dressing N before corn reaches the V8 stage of growth is a useful tool to compensate for N lost by denitrification, leaching, and to apply N close to the time of highest need in the plant’s lifecycle (Figure 1). From flowering to maturity, corn products can take up from 30% to 40% of their total N, over 50% of their total P, and over 40% of their total sulfur at maturity.
Side-dress applications should be part of a fertility plan that has the majority of N applied in the fall or spring prior to planting, followed by an early in-crop application (V5 to V8) of a portion of the total N needed by the crop. The risk with side-dressing is that conditions may delay the application and corn gets too tall to avoid breaking stalks or damaging roots. Consider side-dress for fields that are prone to denitrification or leaching loss. Speed of application will be dictated by the size of the applicator, N source, soil conditions, row spacing, and size of the corn.
When selecting a method for sidedress application, consider avoiding crop injury, reducing N losses, and speed of application. Recommendations from North Dakota State University (ranked best to worst):2
- Anhydrous ammonia injection on loam or coarse textured soils.
- Coulter applied UAN, or cultivator applied UAN/urea.
- Dribbling/streaming UAN from a high clearance sprayer between the rows.
- Flying on urea by air.
Use a urease inhibitor to limit volatilization with products containing urea-based N. Early application increases chances for incorporation by rainfall and reduces risk of crop injury. As much as 30 percent of broadcast urea can volatilize if there is no rainfall within approximately 10 days after the application.3
Many years of research in the Corn Belt has shown that side-dressing is a nitrogen management practice that has consistently produced high yields. Results of research conducted at the University of Minnesota Southwest Research and Outreach Center, from 1998 to 2006 has confirmed those findings.4
Side-dressing N is a good strategy to address N loss situations from leaching or denitrification. It also can deliver N closer to the time of high demand from corn. The benefit for side-dress N can be substantial (Figure 2). North Dakota State University research has demonstrated the potential economic benefit of investing in side-dress equipment and split N applications versus preplant applications.5 They have shown that side-dressing N after a wet spring can be potentially worth 50 bu/acre.
Sources: 1 Ciampitti, I.A., et al. 2013. Maize Nutrient Accumulation and Partitioning in Response to Plant Density and Nitrogen Rate: I. Macronutrients. Agronomy Journal. 105: 783-795. 2 Franzen, D. 2011. Corn Side-Dress Options. North Dakota State University Crop and Pest Report. 3 Fernandez, F. 2011. Sidedressing Nitrogen for the Corn Crop. The Bulletin, University of Illinois. 4 Rhem, G. 2008 Sidedress Thoughts. University of Minnesota. 5 Franzen, D. 2012. Nitrogen Calibration for Corn. North Dakota State University.