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Is My Nitrogen Still There?


If you applied ammonia last fall, you’re probably wondering if it’s still there, especially with the excessive rain we got in December.

Don’t assume all nitrogen (N) applied last fall is gone. That’s the word from Dr. John Sawyer, an Iowa State University Extension soil fertility specialist. “It’s hard to make an estimate of losses for such an extreme event and time of the year,” he noted in a recent article.

In mid-December, Sawyer noted that N fertilizer or manure applications within the previous few weeks or so should not have an issue with nitrate loss. He added that it’s also too early to make decisions about adding more N in the spring.

The most important consideration for estimating potential nitrate loss from December’s torrential rainfall is how much applied ammonium converted to nitrate. If fall applications were made when the soil temperature was below 50 degrees, the amount of nitrate formed will be low and loss will be low. Conversely, if applications were made in early fall with warm soil temperatures and many days for nitrification to occur, large amounts of nitrate could be formed. This means that earlier fall (September, October) applications are at higher risk of loss than late fall (late November, early December) applications.

Let’s make a plan
Instead of worrying that your N is gone, it’s more prudent to evaluate specific situations and see how weather conditions develop in the weeks ahead. With the soil profile moisture recharged, there’s the potential for excessively wet soil conditions this spring. This will have a greater impact on N loss than wet soils last fall.

Also, while it’s easy to focus on N, don’t forget to consider the law of the minimum. This states that yields are reduced when one or more nutrients are lacking. Since 60% of your yield potential depends on soil fertility, it’s important to make sure you feed your crop with the right amounts of N, phosphorus, potassium, and micronutrients.

We’re ready to help you fine-tune your soil fertility and get your 2016 crop off to a good start. Talk to your First Cooperative Association agronomist for more information. We appreciate your business and look forward to working with you.

Mark Braunschweig 
Agronomy Manager 
Office: 877-753-5400
mbraunschweig@firstcoop.com

See other stories from this month's First Coop Association News:

MANAGEMENT: We’re in This Together
FEED: Distractions Abound, Stay Focused
GRAIN: Don’t Be the Last to Sell
ENERGY: It’s Time to Hold Off