Nitrogen can be a challenging fertilizer for corn growers. Everyone has their preferred method of application, the method that works best for their fields. Whether that is fall or spring applied, broadcast, in furrow or side-dress in season. It might be anhydrous, urea or liquid 32 percent. The trouble with nitrogen is the weather can really impact application and effectiveness.
“Last fall, 2018 was probably the worst fall anhydrous ammonia season in recorded history,” said Tim Laatsch, Technical Agronomy Manager for Koch Agronomic Services (Koch), during a recent phone interview. “Which has really pushed a tremendous amount of field work into the spring.”
Growers need to start thinking about their nitrogen application in a best case, second best case and worst-case scenario. They need to have back up plans ready and have that planned out with their fertilizer dealer.
“I would encourage farmers to use this time, while we're waiting for the fields to dry out, to communicate with their retailers and start developing contingency plans for nitrogen,” said Laatsch. “Waiting until the last minute to change plans is going to put the farmer and retailer in a difficult position of potentially not having the right product available when they need it.”
There is a time frame, while the corn plant is still young, V5-V7, that the plant is determining the potential size of the final ear, essentially establishing placing a ceiling on yield potential. It is checking the gas tank, see how much nutrients are available to support a final seed production.
If growers miss that window with their nitrogen, if that nitrogen is not available to the plant at that time, it will cost yield.
Now, just because April has been wet, that does not mean farmers will not be able to get pre-plant nitrogen out.
“There are some places where best case is still likely to happen,” he said. “I would encourage people who have the good fortune of being in that situation to avoid this misperception that spring applications of anhydrous ammonia will not benefit from the use of the nitrification inhibitors.”
Nitrification inhibitors have been a crucial technology to farmers. They slow the loss of nitrogen in the field, preventing it from either denitrifying off or leaching away and keep it plant available.
Koch has recently developed and released a new nitrification inhibitor called CENTURO for use with anhydrous in the spring or fall application and with UAN in spring applications.
“We have done a series of replicated experiments with fall and spring applications of CENTURO across the Midwest,” he said. “What we are seeing is an economic yield advantage of six bushels per acre on average for spring anhydrous that was treated with CENTURO compared to untreated anhydrous.”
Now, if this wet weather does persist and growers have to chose between timely planting and nitrogen applications, there are post planting options.
“Urea and UAN provide much more time efficient options at planting or very close to planting with a better degree of seedling safety from ammonia burn,” said Laatsch. “You can run a broadcast application of UAN along with your herbicides and apply that to the field.”
Broadcast UAN does have a greater risk of volatizing off as ammonia, so stabilizing that nitrogen with a urease inhibitor becomes crucial.
“Our newest technology, that we just got registered called ANVOL, has the same active ingredient as AGROTAIN, but also includes a second active ingredient which is new to the world of chemistry that we call DUROMIDE,” he said. “It is the strongest and longest lasting urease inhibitor available in the market now.”
Having a urease inhibitor with the UAN application helps the nitrogen will stay in the soil and be available when the plant needs it during that V5-V7 window.
The worst-case scenario this spring would be the optimum planting date has passed and growers need to prioritize getting the seed in the ground over putting out fertilizer. In that case, it is likely the grower will need to change both the type of nitrogen fertilizer and the application method.
“If you defer all or most of your nitrogen until later in the core vegetative growth stages and you don't optimize that primordial ear, but you wait until V7 or later to put all your nitrogen on, that approach typically carries a significant yield penalty,” he said.
This is why it is so important to have those back-up plans figured out with the ag retailers and fertilizer dealers ahead of time.
Should the spring stay wet and fertilizer applications not go as planned, there will be a lot of growers trying to get their nitrogen applied later, post plant or side-dress. Being towards the bottom of that list could cost significant yield.