Managing spring nitrogen applications

Farm Forum

If you didn’t have the opportunity to apply nitrogen last fall, now is a good time to start thinking about it. Good management decisions with pre-plant nitrogen can improve your efficiency. The challenge, however, is to minimize losses since your corn crop won’t need most of its nitrogen until it reaches V10 on through early grain fill. Therefore, if you’re willing to make split applications, performing both pre-plant and sidedress applications of nitrogen could increase nutrient levels while reducing your nitrogen input cost for 2014.

Applying some nitrogen before planting is ideal so you can avoid early-season deficiencies and reduce the risks associated with weather conditions that prevent in-season fertilization. Avoiding crop damage is key, however, as wet conditions and a short timeframe make spring nitrogen applications a challenge.

“If you’re out there applying nitrogen when it’s too wet, you’ll smear the sidewall and create a compaction layer,” WinField Master Agronomy Advisor Bryce Brobst cautions. “At the same time, you should leave at least two weeks between nitrogen application and planting for the nitrogen to disperse. This helps prevent seedling damage.”

“Also, it’s better to plant off to the side of the spring applications, because you can burn the roots if you plant right over the top of it and the plant will look like it’s undergoing drought-stress,” he adds.

Anhydrous ammonia is often the product of choice for pre-plant because of its cost advantage and the fact that it takes the longest time to convert to nitrate-nitrogen. Brobst says sealing the ground behind anhydrous ammonia applications is essential to prevent loss.

“With anhydrous ammonia coming out as a gas and a liquid, it can escape up through the cracks in the ground,” Brobst explains. “So whether you use closing discs or simply pull a chain behind you, you want the ground to crumble in immediately after the application to seal it in.”

The amount of nitrogen supplied by the soil or lost to spring rainfall is an unknown. So if you make one large nitrogen application before planting, you lose the ability to adjust rates based on the effects of spring weather. Oftentimes you can reduce your input costs if you make a small pre-plant application and then return to sidedress the corn when it’s about 15 inches tall. This is because there’s less time for nitrogen to be lost between application and use.

Another way to manage nitrogen costs is to rotate crops for nitrogen credits. For example, if planting corn after soybeans, a credit of 30 to 60 lbs. may be taken. Depending on soil type, a credit of 70 to 150 lbs. of nitrogen may be taken when corn follows alfalfa.

Yet another option is to plant genetics that are more tolerant to lower fertility. Western and Northern genetic types are tolerant to lower nitrogen when populations are adjusted downward.

Consult your local WinField retailer for help in creating a soil fertility program that is customized to your fields. And, be sure to visit your local Answer Plot location in 2014 to see how popular hybrids in your area respond to different management levels.