Koch: fall nitrogen fertilizer application requires careful planning
Applying nitrogen fertilizer in the fall can be a smart practice - both financially and operationally - for corn and wheat growers who want to save money with fall fertilizer purchases and focus on planting next spring. But applying nitrogen at this time of year presents greater risk from potential nitrogen loss. Koch Agronomic Services, LLC (KAS) shares tips to help protect nitrogen and growers' investment in this vital crop input.
"Following the 4Rs of Nutrient Stewardship (Right Fertilizer Source, Right Rate, Right Time and Right Place) is especially important in the fall when crops are months away from development and their maximum nitrogen uptake, leaving it vulnerable to loss from fluctuating weather conditions," said Greg Schwab, PhD, director of agronomy at KAS.
Schwab offers some general guidelines for growers:
- For most regions, anhydrous ammonia is the preferred fertilizer for fall applications on acres that will be planted the following spring. That's because ammonia converts to nitrate in the soil more slowly than other forms of nitrogen.
With anhydrous, accepted best management practices call for application only after soil temperatures drop to 50 degrees and lower. Typically, this is in late October, although in 2016, soils began to cool later and applications occurred in early November, Schwab said.
- UAN is vulnerable to fall nitrogen loss because it contains nitrates that are susceptible to loss at the time of application, Schwab said.
- In limited northern regions (parts of Minnesota, North Dakota and Montana), growers can apply fall urea. Below that latitude, soils are too warm and the weather too variable for safe application.
Growers in northern areas should time urea application just before freezing because the rate of nitrate conversion on completely frozen ground is near zero. Schwab cautions against applying to already frozen ground or snow-covered soil where there's the possibility of snow melting. In all cases of fall urea application, however, there is a risk of volatilization that's best addressed with AGROTAIN nitrogen stabilizer or with use of SUPERU fertilizer, another KAS product that protects against all three forms of nitrogen loss, Schwab said.
"Enhanced efficiency fertilizers such as AGROTAIN stabilizer and SUPERU fertilizer can help turn a less efficient agronomic practice into a more efficient agronomic practice," he said.
AGROTAIN and SUPERU fertilizer represent a portfolio of proven enhanced efficiency fertilizer products available from KAS. AGROTAIN nitrogen stabilizer comes in a variety of formulations to meet specific blending and application needs: AGROTAIN ADVANCED 1.0; AGROTAIN ULTRA and AGROTAIN DRI-MAXX.
Regardless which type of fertilizer is applied, Schwab recommends a split application of 50 percent to 60 percent in the fall and the remainder in the spring to minimize the potential of loss, with spring applications determined by yield potential.
"Growers who want to apply fertilizer over the next few weeks should look for guidance from their land-grant universities or trusted retail advisor, who can offer advice appropriate for their regions," Schwab said.