The Smart Way to Sidedress

With difficult spring conditions, sidedress may be a farmers best application option.


In a spring season like the one we had in 2019, many turned to sidedress nitrogen applications. Because planting was delayed across most of the country, you likely had to adjust your nitrogen application timing. In many states, farmers chose to sidedress much of their nitrogen.

Sidedressing nitrogen can be incredibly effective and is a recommended practice from The Fertilizer Institute’s 4R nutrient stewardship program. Specifically, sidedress applications allow for fine-tuning of preplant (or fall-applied) nitrogen rates and provides additional nitrogen when the crop needs it the most.

Sidedress, though beneficial, can be a fickle process if not done correctly. Soil type, previous nitrogen applications and weather conditions impact the how, what and when of sidedress.

Despite that, here are some best practices to keep in mind as you consider sidedress application this year:

Conduct a pre-sidedress soil nitrate test.

This test can confirm how much nitrogen was lost due to leaching or denitrification after preplant and/or fall fertilizer applications so more nitrogen can be applied at the right rate. It is recommended to sample the soil when corn is 6 to 12 inches tall, or in late May to early June. It’s also important to sample areas that are similar in texture and 10 to 20 acres in size. This test works best if you avoid previous fertilizer application bands, including starter and anhydrous ammonia bands. Tests should also consist of 15 to 20 cores per sample.

Apply a readily available nitrogen source at the right time.

Urea ammonium nitrate (UAN) and urea are two of the best options for sidedress fertilizer because they are readily available to the plant after application. Anhydrous ammonia is also easily accessible, and widely used; however, it can be tricky to use in sidedress because it can be easily lost if soil conditions and application method aren’t precise.

When anhydrous ammonia is knifed in, the openings must fully close to keep it from escaping. Therefore, if the soil is damp, clumpy or very sandy, this is hard to achieve. UAN (28% or 32%) can be dribbled on the soil surface or injected into the soil between rows, and urea can be applied broadcast. If you’re choosing an injection or knifing method, it is important to confirm where the rows are to avoid burning the new corn plants. If you’re broadcasting, there can be slight leaf burn if the fertilizer product is concentrated in one area, but the impact is largely cosmetic and will not affect yield.

Iowa State University Extension research shows that maximum nitrogen uptake in corn occurs between V9 and V18. Nitrogen applied prior to V9 — V4 through V6 preferably — has shown to be one of the most effective ways to ensure corn can take up the maximum nitrogen after V8. This is prime for sidedress applications, which typically occur late May to mid-June, depending on planting date and weather.

Protect sidedress nitrogen from leaching and denitrification.

Although urea, UAN and anhydrous ammonia are preferred sources for sidedress applications, they are immediately vulnerable to loss through leaching and denitrification. A nitrogen stabilizer that protects against these forms of loss, such as Instinct® and N-Serve® nitrogen stabilizers, is recommended to ensure the nitrogen stays in the root zone during critical growth periods. By keeping nitrogen in the soil during corn’s key growth stages, Instinct and N-Serve maximize yield potential and ROI.

Find more information on how to keep nitrogen where it belongs and protect against leaching and denitrification during sidedress by visiting

® ™ Trademarks of Dow Agrosciences, DuPont or Pioneer, and their affiliated companies or their respective owners. Instinct is not registered for sale or use in all states. Contact your state pesticide regulatory agency to determine if a product is registered for sale or use in your state. Federal law does not require any person who applies or supervises the use of Instinct to be certified in accordance with EPA regulations and state, territorial and tribal laws. Some states may have additional requirements related to liquid manure and nitrogen stabilizers. Be sure to consult your state or local Extension service to understand your requirements. When applying Instinct to deep pits, appropriate manure agitation safety steps should be followed. Instinct should be applied directly to the deep pit prior to pumping the pit; a thorough agitation system must be operating in order to evenly distribute Instinct within the deep pit; applicators and handlers of Instinct and manure treated with Instinct are required to use proper protective equipment as stated on the product label; air ventilation systems must be operational inside barns. Do not fall-apply anhydrous ammonia south of Highway 16 in the state of Illinois. Always read and follow label directions. © 2019 Corteva.