Spring Nitrogen Application 101: What, Where, When and How Much
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It’s no doubt you feel the pressure every spring to get nitrogen applications right. Fertilizer is one of the top inputs, and because it takes up a large portion of a farm’s annual budget, there is little room for error via over- or underapplying, nitrogen loss or application timing, among others.
Because there are so many variables that impact an individual farm’s nitrogen management, there can be a lot of confusion and indecision about the what, where, when and how much of spring-applied nitrogen. This is especially true for those who use or are considering using a nitrogen stabilizer in their plan.
However, there are several best practices for spring applications that can help you create smart nitrogen management plans that set you up for a year of success. Below are a few to keep in mind as you navigate tough nitrogen questions this year.
The What
Nitrogen Fertilizer
Choosing what type of nitrogen fertilizer is dependent on four factors: soil type, climate, available equipment and budget. For spring applications, anhydrous ammonia, urea and urea ammonium nitrate (UAN) are the most typical nitrogen fertilizer sources and each offer specific advantages depending on the farmer’s situation.
“Anhydrous ammonia, urea and UAN (28%) all work well in the spring. Anhydrous ammonia will take longer to apply, and you may want to wait a few days before any additional tillage and planting,” said Jeff Moon, market development specialist, Corteva Agriscience.
According to University of Minnesota Extension research, anhydrous ammonia is often also the least expensive nitrogen source and contains the highest percentage of nitrogen by weight.
Urea and UAN have a much lower nitrogen concentration but are easy to use and transport and can be easy to mix with other materials.
“You may be able to impregnate your herbicide with your urea and 28% applications to save a trip in the spring too,” Moon said.
Nitrogen Stabilizer
In addition to what type of fertilizer, you should be considering what type of nitrogen stabilizer to incorporate.
“Spring stabilization is just as important as fall stabilization,” Moon said. “Our potential for greatest nitrogen loss is in the spring and early summer, so we need to take steps to ensure that the nitrogen will be in place when the crop needs it.”
Up to 30% of nitrogen loss happens above ground and up to 70% can be lost below ground. Choosing a nitrogen stabilizer, such as N-Serve® and Instinct® nitrogen stabilizers, or a combination of stabilizers, is the best way to ensure your nitrogen is protected regardless of fertilizer type or form of loss.
“With our portfolio, we have the ability to stabilize any form of nitrogen and any application technique that you choose. Nitrogen is susceptible to loss through volatilization, leaching and denitrification. There is no excuse not to use the tools available to protect that nitrogen investment,” Moon said.
Yet, a concern that some growers have expressed in spring applications is that they don’t want to tie up their nitrogen by using a stabilizer.
“N-Serve and Instinct do not ‘tie up’ nitrogen. We aren’t waiting for it to release or break down — the nitrogen is always available for the corn plant to use,” Moon said. “That’s the beauty of using the products in our portfolio. They help maximize yield from the moment they’re applied.”
The Where
If fall applications have been made, you may wonder where you would need to apply spring nitrogen to prepare for an optimal growing season. The answer here lies in soil testing, and there are a few times and options to find the areas in your fields in most need of nitrogen application.
Preplant soil nitrate test — A preplant soil nitrate test measures the amount of residual or carryover nitrogen available in the active root zone and indicates the amount of nitrogen in the nitrate form present in the soil. A wet spring increases the likelihood of leaching and denitrification as ammonium nitrogen converts to nitrate-N, the form prone to loss. The preplant test should be made if a large amount of nitrogen was applied the previous year and yield was lower than expected. This is an indication that there still may be a large amount of nitrate in the soil.
Pre-sidedress soil nitrate test — If nitrogen applications are lowered based on carryover sample results, you should consider the pre-sidedress soil nitrate test. This test allows you to apply more nitrogen for peak growth at critical nutrient uptake stages. Samples should be taken when corn is 6 to 12 inches tall or in late May to early June. Sample areas that are of similar soil type 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.
The When
Preplant? Sidedress? Split application? The timing of spring-applied nitrogen is influenced by the weather and when planting will begin. Preplant is always recommended so long as it does not delay planting. When weather does not allow for preplant, you will need to reassess when they can get out again to add supplemental nitrogen.
Sidedress is one option, and something you will need to work on is to identify the correct timing for proper soil incorporation and minimal negative impact to the already growing crop.
However, in many instances, split applications consisting of preplant and sidedress are extremely effective at impacting yield. When used alongside soil tests, split application methods allow for real-time adjustments to nitrogen application timing and rates for maximum crop impact.
The How
Another leading question regarding spring applications is how much nitrogen should be applied. Estimating the right amount of nitrogen to apply is a delicate science. Too much nitrogen can be costly and cause negative environmental effects. Too little nitrogen can cause yield to suffer, particularly when not protected from losses due to volatilization, leaching or denitrification.
“We recommend using the full rates of N-Serve and Instinct with our spring applications,” Moon said. “We may recommend reduced rates when we get to sidedress applications.”
Overall, spring applications are just as important as fall applications. They require detailed planning, but by following some best practices for what, where, when and how much to apply, you can build a nutrient management plan that helps to ensure success in the fields.
1 Fernández, F. G. 2016. The Three Biggies: Urea, Anhydrous Ammonia, and UAN.
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.
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